CN112400077B - Pneumatic actuator and pneumatic system comprising a pneumatic actuator - Google Patents

Abstract

In one aspect, a vacuum actuator for use in a vehicle vacuum system is provided that includes a housing, an output member, an inter-chamber valve member, a first membrane, a second membrane, a first membrane biasing member, and a second membrane biasing member. The actuator housing includes a first chamber and a second chamber. The first chamber can be fluidly connected to a first vacuum source. The first diaphragm is movable at a first selected pressure in the first chamber by a pressure differential across the first diaphragm against the first biasing member to move the inter-chamber valve member from the closed position to the open position. The second membrane biasing member urges the output member toward the second position. The second diaphragm is movable by a pressure differential across the second diaphragm at a second selected pressure in the second chamber to move the output member to the first position. The first selected pressure is less than the second selected pressure.

Description

Pneumatic actuator and pneumatic system including pneumatic actuator

Cross References to Related Applications

This application claims the benefit of U.S. Patent Application No. 62/694,158, filed July 5, 2018, the contents of which are hereby incorporated by reference in their entirety.

technical field

The description generally relates to pneumatic actuators and pneumatic systems. In particular, the following relates to vacuum actuators for vacuum pumps.

Background technique

In the automotive industry it is known to provide vacuum systems for various purposes such as powering a brake booster, for operation of a turbo wastegate, and for other functions. In some applications, when the vacuum in the vacuum system is too low (i.e., when the pressure in the vacuum system is so high that there is not enough vacuum to generate the force required for desired device operation), vacuum actuators are used to Mechanically initiates the operation of the vacuum pump. Vacuum actuators typically include a diaphragm in a housing with a spring urging the diaphragm in one direction. An actuator arm is connected to the diaphragm. The amount of vacuum present on one side of the diaphragm indicates whether the diaphragm has overcome the spring and moved the actuator to a new position. A problem with typical vacuum actuators is that they tend to oscillate at pressures very close to the pressure that triggers actuation of the vacuum actuator, causing the vacuum actuator to repeatedly activate and deactivate the vacuum pump. To solve the chattering problem, some vacuum pumps have been fitted with solenoids which are operated by an ECU which reads the pressure in the vacuum system via a pressure sensor. However, this solution can be expensive and adds complexity to the vehicle's vacuum system. It would be desirable to provide a vacuum actuator that is relatively simple and inexpensive, avoids the use of electronics, but solves the problem of jitter caused by typical vacuum actuators.

Contents of the invention

Broadly, and in some aspects, the present disclosure relates to pneumatic actuators and pneumatic systems. In some aspects, the pneumatic actuator is a vacuum actuator and the pneumatic system is a vacuum system.

In one aspect, there is provided a vacuum actuator for use in a vehicle vacuum system, the vacuum actuator comprising an actuator housing, an actuator output member, an inter-chamber valve member, a first membrane, A second membrane, a first membrane biasing member, and a second membrane biasing member. The actuator housing includes a first chamber and a second chamber. The first chamber is fluidly connectable to a first vacuum source to provide a first chamber pressure to the first chamber. The second chamber is fluidly connectable to the first vacuum source through a second chamber feed conduit. The second chamber has a second chamber pressure. The actuator output member is movable relative to the actuator housing between a first output member position and a second output member position. The inter-chamber valve member is movable between a closed position, in which the inter-chamber valve member prevents fluid communication between the first chamber and the second chamber, and an open position, in which the inter-chamber valve member The valve member allows fluid communication between the first chamber and the second chamber. The first membrane acts as a wall of the first chamber such that a first side of the first membrane is exposed to the first chamber pressure and a second side of the first membrane is exposed to a pressure external to the first membrane. The first membrane is connected to the inter-chamber valve member. The second membrane acts as a wall of the second chamber such that the first side of the second membrane is exposed to the second chamber pressure and the second side of the second membrane is exposed to the second membrane external pressure. The second membrane is connected to the actuator output member. The first membrane biasing member is positioned to exert a first biasing force to urge the interchamber valve member toward the closed position. The first membrane is movable to move the inter-chamber valve member from the closed position to the open position by a pressure differential across the first membrane against a first biasing force when the first chamber pressure is less than a first selected pressure. The second membrane biasing member is positioned to apply a second biasing force to urge the actuator output member toward the second output member position. The second membrane is movable to move the actuator output member from the second position to the first position by a pressure differential across the second membrane against a second biasing force when the second chamber pressure is less than a second selected pressure. Location. The first selected pressure is less than the second selected pressure. The first vacuum source has a first volume and the second chamber has a second volume, wherein the first and second volumes are sized relative to each other such that a reduction in the first chamber pressure to less than the first selected pressure causes Movement of the first membrane moves the inter-chamber valve member from the closed position to the open position, which exposes the second chamber to the first chamber, thereby reducing the second chamber pressure below a second selected pressure .

In another aspect, a vehicle vacuum system is provided and includes: a first vacuum source that is less than ambient air pressure outside the vehicle vacuum system; a vacuum load that uses a first A vacuum source operates to increase the pressure in the first vacuum source; a vacuum pump fluidly connected to the first vacuum source and operable to decrease the pressure in the first vacuum source; and a vacuum actuator. A vacuum actuator includes an actuator housing having a first chamber and a second chamber, an actuator output member, and an inter-chamber valve member. The first chamber is fluidly connectable to a first vacuum source to provide a first chamber pressure to the first chamber, wherein the second chamber is fluidly connectable to the first vacuum source via a second chamber feed conduit, And wherein, the second chamber has a second chamber pressure, a first membrane, a second membrane, a first membrane biasing member, and a second membrane biasing member. The actuator output member is movable relative to the actuator housing between a first output member position and a second output member position. The actuator output member is connected to a clutch that controls the connection between the rotor of the vacuum pump and a rotor drive source for operation of the rotor such that movement of the actuator output member to the second output member position drives the rotor through the clutch A source is connected to the rotor to drive the rotor to reduce pressure in the first vacuum source, and movement of the actuator output member to the first output member position disconnects the rotor drive source from the rotor to stop driving the rotor. The inter-chamber valve member is movable between a closed position, in which the inter-chamber valve member prevents fluid communication between the first chamber and the second chamber, and an open position, in which the inter-chamber valve member The valve member allows fluid communication between the first chamber and the second chamber. The first membrane acts as a wall of the first chamber such that a first side of the first membrane is exposed to the first chamber pressure and a second side of the first membrane is exposed to a pressure outside the first membrane, wherein the first The membrane is connected to the inter-chamber valve member. The second membrane acts as a wall of the second chamber such that the first side of the second membrane is exposed to the second chamber pressure and the second side of the second membrane is exposed to the second membrane external pressure. The second membrane is connected to the actuator output member. The first membrane biasing member is positioned to exert a first biasing force to urge the interchamber valve member toward the closed position. The first membrane is movable by a pressure differential across the first membrane against a first biasing force to move the inter-chamber valve member from a closed position to an open position when the first chamber pressure is less than a first selected pressure. The second membrane biasing member is positioned to apply a second biasing force to urge the actuator output member toward the second output member position. The second membrane is movable by a pressure differential across the second membrane against a second biasing force to move the actuator output member from the second position to the first position when the second chamber pressure is less than a second selected pressure . The first selected pressure is less than the second selected pressure. The first vacuum source has a first volume and the second chamber has a second volume, wherein the first and second volumes are sized relative to each other such that a reduction in the first chamber pressure to less than the first selected pressure causes Movement of the first membrane moves the inter-chamber valve member from the closed position to the open position, which exposes the second chamber to the first chamber, thereby reducing the second chamber pressure below a second selected pressure .

In yet another aspect, a vacuum actuator for use in a vehicle vacuum system is provided and includes an actuator housing, an actuator output member, a first membrane, a second membrane, A first film biasing member and a second film biasing member. The actuator housing includes a first chamber and a second chamber, wherein the first chamber is at a first chamber pressure. The second chamber has a second chamber pressure. The actuator output member is movable relative to the actuator housing between a first output member position and a second output member position. The first membrane acts as a wall of the first chamber such that a first side of the first membrane is exposed to the first chamber pressure and a second side of the first membrane is exposed to a pressure external to the first membrane. The first membrane is operatively connected to the actuator member to move the actuator output member to the first output member position. The second membrane acts as a wall of the second chamber such that the first side of the second membrane is exposed to the second chamber pressure and the second side of the second membrane is exposed to the second membrane external pressure. The second membrane is operatively connected to the actuator output member to move the actuator output member to the second output member position. The first membrane biasing member is positioned to apply a first biasing force to the first membrane. The first membrane is movable to move the actuator output member from the second output member position to The first output member position. The second membrane biasing member is positioned to apply a second biasing force to the second membrane and the actuator output member to urge the output member toward the second output member position. The second membrane is movable to move the actuator output member from the second position to the first position by a pressure differential across the second membrane against a second biasing force when the second chamber pressure is less than a second selected pressure. Location. The first selected pressure is less than the second selected pressure. The first membrane biasing member has a first spring constant that determines the first selected pressure, and the second membrane biasing member has a second spring constant that determines the second selected pressure.

Other technical advantages will become apparent to one of ordinary skill in the art upon examination of the following figures and descriptions.

Description of drawings

For a better understanding of the embodiments described herein and to show more clearly how they may be practiced, reference will now be made, by way of example only, to the accompanying drawings in which:

1 is a schematic diagram of a vehicle engine including a vacuum pump according to an embodiment of the present disclosure;

FIG. 2 is a schematic diagram illustrating various components of a vacuum system, including a vacuum pump and a vacuum actuator for the vacuum pump, wherein the clutch is in a disengaged state;

Figure 2A is a schematic diagram showing a vacuum pump and an actuator for the vacuum pump, wherein the clutch is engaged;

Figure 3 is a cross-sectional perspective view of the actuator shown in Figure 2;

4 is a cross-sectional side view of a portion of the vacuum system including the actuator as shown in FIG. 2 in a first state;

5 is a cross-sectional side view of a portion of the vacuum system including the actuator as shown in FIG. 2 in a second state;

6 is a cross-sectional side view of a portion of the vacuum system including the actuator as shown in FIG. 2 in a third state;

7 is a cross-sectional side view of a portion of the vacuum system including the actuator as shown in FIG. 2 in a fourth state; and

8 is a cross-sectional side view of a portion of the vacuum system including the actuator as shown in FIG. 2 in a fifth state.

Objects depicted in the drawings are not necessarily drawn to scale unless specifically indicated otherwise.

Detailed ways

For simplicity and clarity of illustration, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements. Additionally, numerous specific details are set forth in order to provide a thorough understanding of the embodiments described herein. However, it will be understood by those of ordinary skill in the art that the embodiments described herein may be practiced without these specific details. In other instances, well-known methods, procedures, and components have not been described in detail so as not to obscure the embodiments described herein. It should be understood at the outset that while exemplary embodiments are shown in the drawings and described below, the principles of the disclosure may be implemented using any number of techniques, whether currently known or not. The present disclosure should in no way be limited to the exemplary implementations and techniques illustrated in the figures and described below.

Unless the context dictates otherwise, the various terms used throughout this specification can be read and understood as follows: as used throughout, "or" is inclusive as if written "and/or"; as used throughout Singular articles and pronouns include their plural forms, and as used throughout, plural forms and pronouns include their singular forms; similarly, gendered pronouns include their corresponding pronouns, and thus pronouns should not be construed as referring to the Any content contained in is limited to use, implementation, performance, etc., by a single gender; "exemplary" should be read as "illustrative" or "exemplary" and not necessarily as "exemplary" in comparison to other embodiments preferred". Further definitions of terms may be set forth herein; as will be understood from a reading of this specification, such further definitions may apply to previous and subsequent instances of those terms.

Modifications, additions, or omissions may be made to the systems, devices, and methods described herein without departing from the scope of the present disclosure. For example, components of systems and devices may be combined or separated. Furthermore, the operations of the systems and devices disclosed herein may be performed by more, fewer or other components, and the methods described may include more, fewer or other steps. Furthermore, the steps may be performed in any suitable order. As used herein, "each" refers to each member of a group or subgroup of a group.

In one aspect, the present disclosure relates to a vacuum actuator 36 that may, for example, be connected to a clutch for a vacuum pump or to some other device. In some embodiments, the vacuum actuator 36 operates more stably between one actuation state and the other without suffering from jitter like other typical vacuum actuators of the prior art. Additionally, the vacuum actuator 36 achieves this stability without the need for electronic solenoids, which have been used in the past on conventional prior art vacuum actuators to address wobble issues. Additionally, in some embodiments, the vacuum actuator 36 can have a selectable pressure by selecting the two springs that determine the pressure required to move the vacuum actuator 36 between the actuated states of the vacuum actuator 36. and another selectable pressure at which the vacuum actuator 36 moves to one actuated state and at which the vacuum actuator 36 moves to the other actuated state.

Referring to FIG. 1 , which is a schematic diagram of a vehicle engine 10 . Engine 10 includes a crankshaft 12 that drives one or more camshafts 14 via an annular drive member 16 which may be, for example, a timing belt or a timing chain. For illustration purposes only, the camshaft 14 is shown with two cams 18 located on the camshaft 14 . It should be understood that the actual number of cams 18 on the camshaft 14 will depend on the number of cylinders the engine has, the number of valves per cylinder and the total number of camshafts used to control the opening and closing of the valves, and other possible factors. Engine 10 is shown in simplified form for the purpose of avoiding extraneous detail.

1 and 2 show (in schematic form) a vacuum pump 22 . Vacuum pump 22 may be any suitable type of vacuum pump, such as a rotary vane vacuum pump. An example of a vacuum pump suitable for vacuum pump 22 is shown and described in PCT publication WO2018137045, the disclosure of which is incorporated herein by reference in its entirety. The vacuum pump 22 is part of a vacuum system 24 located within the vehicle that may serve several purposes. For example, vacuum system 24 may be used to power a vacuum power device 25 such as a brake booster, or for operation of a turbo wastegate (in turbo equipped vehicles), or for any other suitable purpose. The vacuum powered device 25 may be referred to as a vacuum load 25 .

FIG. 2 also shows a clutch 26 which controls the connection between the rotor 28 of the vacuum pump 22 and a rotor drive source for driving the operation of the rotor 28 . In this example, the rotor drive source is the aforementioned camshaft 14 of the one or more camshafts 14 , however, the rotor drive source may alternatively be any other suitable power source for the rotor 28 .

Clutch 26 may be any suitable type of clutch. For example, the clutch 26 shown schematically in this figure is a friction plate clutch. Alternatively (and preferably), clutch 26 may be a coil spring clutch as disclosed in WO2018137045.

The vacuum system 24 also includes a first vacuum source 30 at a pressure P1 , which may initially be equal to or less than the ambient air pressure outside of the vehicle vacuum system 24 . The ambient air pressure is indicated by P3. The first vacuum source 30 may include a vacuum reservoir 32 and one or more vacuum conduits 34 (or portions of vacuum conduits 34) that form part of the vacuum system 24 and communicate with the vacuum reservoir. 32 in fluid communication. For example, in this embodiment, the first vacuum source 30 includes at least portions of vacuum conduits shown at 34a, 34b, 34c and 34d, respectively.

The vacuum load 25 can be fluidly connected to the first vacuum source 30 via a vacuum conduit 34 d and operate using the first vacuum source 30 consuming vacuum, thereby increasing the pressure in the first vacuum source 30 . As can be seen, the vacuum pump 22 is in fluid communication with the first vacuum source 30 and the vacuum pump 22 is operable to reduce the pressure in the first vacuum source 30 (ie, draw a vacuum in the first vacuum source 30 ).

A vacuum actuator 36 is provided and includes an actuator housing 38 having a first chamber 40 and a second chamber 42 , more clearly shown in FIG. 3 . The vacuum actuator 36 also includes an actuator output member 44 , an inter-chamber valve member 46 , a first membrane 48 , a second membrane 50 , a first membrane biasing member 52 , and a second membrane biasing member 54 .

The first chamber 40 is fluidly connected (via vacuum conduit 34a ) to the first vacuum source 30 to provide the first chamber 40 with a first chamber pressure as pressure P1 . The first chamber 40 is defined between an inner partition wall 56 of the actuator housing 38, an outer wall 58 of the actuator housing 38 (which in this example is the first portion 38a of the actuator housing 38) and a first membrane. Between 48.

The second chamber 42 can be fluidly connected to the first vacuum source 30 through a second chamber feed conduit as vacuum conduit 34c. The second chamber 42 is defined between the inner partition wall 56 , the outer wall 58 and the second membrane 50 . The second chamber 42 has a second chamber pressure P2.

The first membrane 48 may be sealingly connected to the actuator housing 38 in any suitable manner. For example, the first membrane 48 may be sandwiched between the first portion 38a of the actuator housing 38 and the second portion 38b of the actuator housing 38 . The second membrane 50 may also be sealingly connected to the actuator housing 38 in any suitable manner. For example, the second membrane 50 may be sandwiched between the first portion 38a of the actuator housing 38 and the third portion 38c of the actuator housing 38 . The first membrane 48 and the second membrane 50 may be made of any suitable material known to those skilled in the art for vacuum actuators.

The actuator output member 44 is movable relative to the actuator housing 38 between a first output member position (shown in FIG. 2 ) and a second output member position (shown in FIG. 2A ). The actuator output member 44 is connected to the clutch 26 such that movement of the actuator output member 44 to the second output member position connects the rotor drive source (e.g., the camshaft 14) to the rotor 28 through the clutch 26 to drive the rotor 28 in turn to Reducing the pressure in the first vacuum source 30 and causing movement of the actuator output member 44 to the first output member position disconnects the rotor drive source 44 from the rotor 28 to stop driving the rotor 28 .

The actuator output member 44 may have any suitable structure. In the figures, the actuator output member 44 is the actuator arm, and the first output member position is the retracted position of the actuator arm relative to the actuator housing, and the second output member position is the actuator arm position. An extended position of the arm relative to the actuator housing, in which the actuator arm extends further from the actuator housing than in the retracted position.

The first membrane 48 acts as a wall of the first chamber 40 such that a first side 60 of the first membrane 48 is exposed to the first chamber pressure P1 and a second side 62 of the first membrane 48 is exposed to the first membrane external pressure. In the example embodiment shown, the first membrane external pressure is ambient air pressure P3, however, in alternative embodiments not shown, the first membrane external pressure may be any other suitable pressure, such as an actuation pressure in other parts of the vacuum actuator housing 38 that are isolated from the ambient environment outside the vacuum actuator 36 .

The first membrane 48 is connected to the inter-chamber valve member 46 . Thus, movement of the first membrane 48 drives movement of the inter-chamber valve member 46 . The inter-chamber valve member 46 is movable between a closed position, in which the inter-chamber valve member 46 prevents fluid communication between the first chamber 40 and the second chamber 42, and an open position, in which , the inter-chamber valve member 46 allows fluid communication between the first chamber 40 and the second chamber 42 .

In the example embodiment shown in the figures, the inter-chamber valve member 46 includes a piston 46 a located in the second chamber 42 , and a connecting arm 46 b extending from the piston 46 a through an aperture in the inner dividing wall 56 . to the first membrane 48 in the first chamber 40 . Preventing air from flowing through the inter-chamber valve member 46 when the inter-chamber valve member 46 is in the closed position may be done in any suitable manner, such as by an O-ring on the rear surface of the piston 46a sealing against the inner dividing wall 56 57 to achieve. As the piston moves away from inner dividing wall 56 , air can flow around piston 46a and around connecting arm 46b through holes in inner dividing wall 56 to provide fluid communication between second chamber 42 and first chamber 42 .

The second membrane 50 acts as a wall of the second chamber 42 such that a first side 64 of the second membrane 50 is exposed to the second chamber pressure P2 and a second side 66 of the second membrane 50 is exposed to the second membrane external pressure. In the example embodiment shown, the second membrane external pressure is ambient air pressure P3, however, in alternative embodiments not shown, the second membrane external pressure may be any other suitable pressure, such as Pressure in other parts of the actuator housing 38 that are isolated from the ambient environment outside the vacuum actuator 36.

The second membrane 50 is connected to the actuator output member 44 . Accordingly, movement of the second membrane 50 drives movement of the actuator output member 44 between the first output member position and the second output member position.

The first membrane biasing member 52 is positioned to exert a first biasing force to urge the interchamber valve member 46 toward the closed position. The first membrane is movable by a pressure differential across the first membrane against a first biasing force to move the inter-chamber valve member 46 from a closed position to an open position when the first chamber pressure P1 is less than a first selected pressure. Location.

The second membrane biasing member 54 is positioned to apply a second biasing force F2 to urge the actuator output member 44 toward the second output member position. The second membrane 50 is movable to move the actuator output member 44 from the second position by a pressure differential across the second membrane 50 against a second biasing force when the second chamber pressure P2 is less than a second selected pressure. Move to first position. In some embodiments, the first selected pressure is less than the second selected pressure.

The first vacuum source 30 has a first volume and the second chamber has a second volume. The first volume and the second volume are dimensioned relative to each other such that a decrease in the first chamber pressure P1 below the first selected pressure causes movement of the first membrane 48 to move the interchamber valve member 46 from the closed position to The open position, which fluidly exposes the second chamber 42 to the first chamber 40, thereby reducing the second chamber pressure P2 below a second selected pressure.

In the second chamber feed conduit 34c is provided a check valve 68 which prevents air from passing from the second chamber 42 through the second chamber if the pressure P2 of the second chamber is higher than the pressure P1 of the first chamber. The chamber feed conduit 34c flows to the first vacuum source 40, but the check valve 68 allows air from the first chamber 40 to pass through the second chamber if the first chamber pressure P1 is higher than the second chamber pressure P2 Feed conduit 34c flows to second chamber 42 . Check valve 68 may be any suitable type of check valve.

Operation of the vacuum system 24 will now be described with reference to FIGS. 4-8 and back to FIGS. 2 and 2A . FIG. 4 shows the vacuum actuator 36 in an initial state when the vehicle is stopped and all pressures, namely P1 , P2 and the first and second membrane external pressures are equal to each other. With these pressures equal, the first and second membrane biasing members 52, 54 hold the inter-chamber valve member 46 in the closed position and the actuator output member 44 in the second position, which causes the clutch 26 engages, as shown in FIG. 2A , thereby operatively connecting the rotor drive source (camshaft 14 ) with the rotor 28 of the vacuum pump 22 . Due to this operative connection, the vacuum pump 22 operates to reduce the pressure P1. During this decrease in the first chamber pressure P1, the inter-chamber valve member 46 remains in the closed position and the check valve 68 prevents the flow of air from the second chamber 42 through the second chamber feed conduit 34c, thereby The second chamber pressure P2 is prevented from being equal to the first chamber pressure P1.

After a period of operation, the first chamber pressure P1 drops below the first selected pressure and the first membrane external pressure (eg, pressure P3 ) overcomes the first chamber pressure P1 plus the first membrane biasing member 52 The first biasing force of , and the first membrane 48 moves to drive the inter-chamber valve member 36 to the open position, as shown in FIG. 5 .

Once the inter-chamber valve member 36 is in the open position, the second chamber 42 is in fluid communication with the first chamber 40 and thus the second chamber pressure P2 drops towards the first chamber pressure P1 until the first chamber pressure P1 and The second chamber pressure P2 reaches an equilibrium based on the size of the first volume V1 compared to the second volume V2. As mentioned above, the drop in the second chamber pressure P2 is sufficient to cause the second chamber pressure P2 to be significantly lower than the second selected pressure. Accordingly, the second membrane external pressure (eg, pressure P3 ) overcomes the second chamber pressure P2 plus the second biasing force of the second membrane biasing member 54 , and the second membrane 50 moves to move the actuator output member 44 Driving to the first output member position, as shown in FIG. 6 , disengages clutch 26 ( FIG. 2 ) and operatively disconnects the rotor drive source from rotor 28 .

With the rotor 28 not operating, the first chamber pressure P1 rises as the vacuum load 25 operates using vacuum from the first vacuum source 30 . However, with the inter-chamber valve member 46 in the open position, the second chamber pressure P2 remains equal to the first chamber pressure P1.

After a period of time, the first chamber pressure P1 has risen sufficiently that the first membrane external pressure can no longer overcome the first biasing force and the first chamber pressure P1, and thus the first membrane 48 moves to move the interchamber valve Member 46 is actuated to the closed position, as shown in FIG. 7 . As the first chamber pressure P1 continues to rise, the check valve 68 opens as needed to allow the second chamber pressure P2 to continue to equalize the first chamber pressure P1. Therefore, the second chamber pressure P2 also continues to rise. After a further period of time, sufficient vacuum applied by the vacuum load 25 causes the first chamber pressure P1 and accordingly the second chamber pressure P2 to rise sufficiently that the pressure outside the second chamber can no longer overcome the second biasing force. Upper second chamber pressure P2. Accordingly, the second membrane 50 moves to drive the actuator output member 44 to the second output member position, as shown in FIG. 8, which drives engagement of the clutch 26, thereby operating the rotor drive source with the rotor 28 (FIG. 2A). is connected to cause the operation of the vacuum pump 22 to reduce the pressure in the first vacuum source 30. At this point, the second chamber pressure P2 will be higher than the first chamber pressure P1 and thus the check valve 68 will be closed.

As noted above, vacuum system 24 and vacuum actuator 36 are advantageous in that they are less prone to vibration. This occurs due to several features. As can be seen, as long as the inter-chamber valve member 36 is open, the second chamber 42 is evacuated such that the pressure P2 of the second chamber 42 equals the pressure P1 of the first chamber. The relative volumes V1 and V2 and the spring rates of the first and second membrane biasing members 52, 54 may be selected such that once the pressure P2 of the second chamber 42 is equal to the first chamber pressure P1 ( This happens sooner), it takes longer for the second chamber pressure P2 to reach the second selected pressure for the actuator output member 44 to be driven to the second output member position. As seen in FIG. 7 , the actuator output member 44 remains in the first output member position even though the inter-chamber valve member 46 has moved to the closed position of the inter-chamber valve member 46 . Thus, even if the first chamber pressure P1 rises for a period of time very close to the pressure required to move the membrane in one direction or the other, the first membrane 48 and the inter-chamber valve member 46 flutter, causing The actuator output member 44 will not flutter, because: as long as the inter-chamber valve member 46 is open, the second chamber pressure P2 will drop very quickly (for example, in less than 0.5 seconds) to a value much lower than that of the second chamber. The selected pressure and the second chamber pressure P2 will take some time before rising to the second selected pressure as the vacuum load 25 depletes the vacuum.

The volumes V1 and V2 may be selected such that the second chamber pressure P2 drops to substantially the same pressure as the first chamber pressure P1 that existed before the inter-chamber valve member 46 opened. For example, if the first volume V1 is about 20 times the size of the second volume V2, the second chamber pressure P2 and the first chamber pressure P1 will be very close to the first chamber pressure before the chamber valve member 46 opens. Pressure P1 is equal in pressure. In an example, the second volume V2 may be about 200ml, while the first volume V1 may be in the range of 4l to 5l. It should be understood that a larger ratio of the first volume V1 to the second volume V2 is better, at least for some first and second selected pressures, as this could potentially lead to second The pressure in chamber 42 drops faster and causes the pressure in second chamber 42 to drop to a greater extent. Alternatively, if the first volume V1 and the second volume V2 are equal, then once the inter-chamber valve member 46 is opened, the second chamber pressure P2 will drop by between the first chamber pressure P1 and the second chamber pressure P2 Bad 50%. Thus, the first volume V1 and the second volume V2 can be selected to control the period of time that the second chamber pressure P2 recovers based on the average rate of consumption of the vacuum generated by the vacuum load 25 until the actuator output member 44 moves The amount of time it takes to reach the second output member position.

It should be noted that the effective surface area of the first membrane is greater than the effective area of the piston 46a for which the air in the second chamber 42 applies pressure. Thus, the inter-chamber valve member 46 will move from the closed position if the pressure differential across the first membrane 48 is sufficiently large, even if the second chamber pressure P2 is higher than the first chamber pressure P1. Effectively, it is beneficial that the second chamber pressure P2 versus the first selected pressure in the first chamber 40 - the first selected pressure at which the first membrane 48 moves to drive the inter-chamber valve member 46 - have relatively little impact.

It should be noted that vacuum load 25 is shown as a single device, such as a brake booster, but those skilled in the art will understand that vacuum load 25 may be multiple devices, each of which may be It may be connected to the first vacuum source 30 independently or via one or more manifolds.

It should also be noted that in alternative embodiments, the actuator output member 44 may instead be a rotating device that is caused to rotate by movement of the second membrane 50 rather than at the actuator output. The member 44 translates between a first output member position and a second output member position.

It should also be noted that the vacuum system 24 shown herein is simplified in the sense that for some purposes there may be other controls not shown or described forming part of the vacuum system 24 but understood to exist. Valves or the like, for example including check valves to allow air to flow into the vacuum pump 22 but prevent air from flowing out of the vacuum pump 22 to the first vacuum source 30 .

It should also be noted that selection of the spring constants of the first and second membrane biasing members 52, 54 can control the first and second selected pressures, the first selected pressure and the second selected pressure. The pressure is the pressure that moves the actuator output member 44 between the first output member position and the second output member position of the actuator output member 44 . In other words, the first membrane biasing member 52 has a first spring constant that determines the first selected pressure, and the second membrane biasing member 54 has a second spring constant that determines the second selected pressure. Thus, by selecting different springs with different spring rates, the vacuum actuator 36 can be tailored to the vehicle's vacuum system 24 for different vehicles having different operating ranges. This advantage exists regardless of whether the vacuum actuator 36 incorporates a membrane. For example, vacuum actuator 36 may operate using first and second chamber pistons instead of first and second membranes. Accordingly, first film biasing member 52 and second film biasing member 54 may be more broadly referred to simply as first biasing member and second biasing member.

As noted above, the first membrane 52 and the second membrane 54 are examples of differential pressure responsive members. Any other differential pressure responsive member may alternatively be used, such as first and second chamber pistons instead of first and second membranes 52, 54, respectively.

The vacuum pump 22 is an example of an air pump. Similarly, vacuum system 24 is an example of a pneumatic system. Accordingly, vacuum conduit 34 may be more broadly referred to as pneumatic conduit 34 . Similarly, vacuum actuator 36 may be referred to more broadly as pneumatic actuator 36 and first vacuum source 30 may be referred to as first pneumatic source 30 . In an example, a pneumatic actuator 36 may be used to control the operation of the pneumatic pump 22 . Where the pneumatic pump 22 is provided to increase the pressure in the first pneumatic source 30, the pneumatic actuator 36 may be configured to operate in the opposite manner to that shown in the figures in the sense that the actuator output member 44 The second position may be actuated to cause operation of the pneumatic pump 22 when the pressure in the second chamber 42 (ie, the second chamber pressure P2 ) drops (rather than increases) beyond a second selected pressure. Similarly, the inter-chamber valve member 46 may be configured such that if the pressure P1 in the first chamber 40 is sufficiently high, the pressure P1 overcomes the first membrane external pressure (eg, pressure P3 ) and the first membrane biasing member 52 The first biasing force moves the first membrane 48 to move the inter-chamber valve member 46 to the open position, which in turn causes fluid communication between the first chamber 40 and the second chamber 42, which makes the second chamber Pressure P2 in chamber 42 increases, thereby moving second membrane 50 to drive the actuator output member to the first output member position, thereby disengaging the clutch and stopping operation of air pump 22 . For this embodiment, it is possible that the inter-chamber valve member 46 could be oriented such that the piston 46a of the inter-chamber valve member 46 is located inside the first chamber 40 rather than the second chamber 42 as shown. middle.

Therefore, in this disclosure, the term "pneumatic" refers to the use of air (or other gas), and is not intended to be limited to positive pressure (ie, pressure greater than atmospheric pressure), but is intended to broadly cover vacuum systems and positive pressure systems .

Although certain advantages have been enumerated above, various embodiments may include some, none, or all of the enumerated advantages.

Those skilled in the art will appreciate that many more alternative implementations and modifications are possible, and that the above examples are merely illustrations of one or more implementations. Accordingly, the scope is limited only by the appended claims and any amendments thereto.

Claims (12)

1. A vacuum actuator for use in a vehicle vacuum system, the vacuum actuator comprising:

an actuator housing comprising a first chamber and a second chamber, wherein the first chamber is fluidly connectable to a first vacuum source to provide a first chamber pressure to the first chamber, wherein the second chamber is fluidly connectable to the first vacuum source through a second chamber feed conduit, and wherein the second chamber has a second chamber pressure;

an actuator output member movable relative to the actuator housing between a first output member position and a second output member position;

an inter-chamber valve member movable between a closed position in which the inter-chamber valve member prevents fluid communication between the first and second chambers and an open position in which the inter-chamber valve member allows fluid communication between the first and second chambers;

a first membrane serving as a wall of the first chamber such that a first side of the first membrane is exposed to the first chamber pressure and a second side of the first membrane is exposed to a first membrane external pressure, wherein the first membrane is connected to the inter-chamber valve member;

a second membrane serving as a wall of the second chamber such that a first side of the second membrane is exposed to the second chamber pressure and a second side of the second membrane is exposed to a second membrane external pressure, wherein the second membrane is connected to the actuator output member;

a first diaphragm biasing member positioned to apply a first biasing force to urge the inter-chamber valve member towards the closed position, wherein the first diaphragm is movable to move the inter-chamber valve member from the closed position to the open position by a pressure differential across the first diaphragm against the first biasing force when the first chamber pressure is less than a first selected pressure; and

a second membrane biasing member positioned to apply a second biasing force to urge the actuator output member toward the second output member position, wherein the second membrane is movable to move the actuator output member from the second output member position to the first output member position by a pressure differential across the second membrane that opposes the second biasing force when the second chamber pressure is less than a second selected pressure,

wherein the first selected pressure is less than the second selected pressure,

wherein the first vacuum source has a first volume and the second chamber has a second volume, wherein the first volume and the second volume are dimensioned relative to each other such that: the reduction of the first chamber pressure to less than the first selected pressure causes movement of the first membrane to move the inter-chamber valve member from the closed position to the open position, which exposes the second chamber to the first chamber, thereby reducing the second chamber pressure to less than the second selected pressure.

2. The vacuum actuator of claim 1, wherein the second chamber feed conduit includes a check valve that prevents air from flowing from the second chamber through the second chamber feed conduit when the second chamber pressure is higher than the first chamber pressure, and that allows air to flow from the first vacuum source into the second chamber when the first chamber pressure is higher than the second chamber pressure.

3. A vacuum actuator as claimed in claim 1, wherein the actuator output member is connected to a clutch which controls a connection between a rotor of a vacuum pump and a rotor drive source for driving operation of the rotor, such that movement of the actuator output member to the second output member position connects the rotor drive source to the rotor through the clutch to drive the rotor, wherein the vacuum pump is fluidly connected to the first vacuum source to reduce the first chamber pressure, and such that movement of the actuator output member to the first output member position disconnects the rotor drive source from the rotor to stop driving the rotor.

4. The vacuum actuator of claim 1, wherein the actuator output member is an actuator arm, and wherein the first output member position is a retracted position of the actuator arm relative to the actuator housing, and the second output member position is an extended position of the actuator arm relative to the actuator housing, the actuator arm extending further from the actuator housing in the extended position than in the retracted position.

5. The vacuum actuator of claim 1, wherein the first volume is at least 20 times greater than the second volume.

6. The vacuum actuator of claim 1, wherein the first membrane external pressure and the second membrane external pressure are both ambient air pressures external to the vacuum actuator.

7. A vehicle vacuum system comprising:

a first vacuum source less than ambient air pressure outside of the vehicle vacuum system;

a vacuum load operating using the first vacuum source, thereby increasing a pressure in the first vacuum source;

a vacuum pump fluidly connected to the first vacuum source and operable to reduce pressure in the first vacuum source;

a vacuum actuator, the vacuum actuator comprising:

an actuator housing comprising a first chamber and a second chamber, wherein the first chamber is fluidly connectable to a first vacuum source to provide a first chamber pressure to the first chamber, wherein the second chamber is fluidly connectable to the first vacuum source through a second chamber feed conduit, and wherein the second chamber has a second chamber pressure;

an actuator output member movable relative to the actuator housing between a first output member position and a second output member position, wherein the actuator output member is connected to a clutch that controls a connection between a rotor of the vacuum pump and a rotor drive source for operation of driving the rotor, such that movement of the actuator output member to the second output member position connects the rotor drive source to the rotor through the clutch to drive the rotor to reduce pressure in the first vacuum source, and such that movement of the actuator output member to the first output member position disconnects the rotor drive source from the rotor to stop driving the rotor;

an inter-chamber valve member movable between a closed position in which the inter-chamber valve member prevents fluid communication between the first and second chambers and an open position in which the inter-chamber valve member allows fluid communication between the first and second chambers;

a first membrane serving as a wall of the first chamber such that a first side of the first membrane is exposed to the first chamber pressure and a second side of the first membrane is exposed to a first membrane external pressure, wherein the first membrane is connected to the inter-chamber valve member;

a second membrane serving as a wall of the second chamber such that a first side of the second membrane is exposed to the second chamber pressure and a second side of the second membrane is exposed to a second membrane external pressure, wherein the second membrane is connected to the actuator output member;

a first diaphragm biasing member positioned to apply a first biasing force to urge the inter-chamber valve member toward the closed position, wherein the first diaphragm is movable to move the inter-chamber valve member from the closed position to the open position by a pressure differential across the first diaphragm that opposes the first biasing force when the first chamber pressure is less than a first selected pressure; and

a second membrane biasing member positioned to apply a second biasing force to urge the actuator output member toward the second output member position, wherein the second membrane is movable to move the actuator output member from the second output member position to the first output member position by a pressure differential across the second membrane that opposes the second biasing force when the second chamber pressure is less than a second selected pressure,

wherein the first selected pressure is less than the second selected pressure,

wherein the first vacuum source has a first volume and the second chamber has a second volume, wherein the first volume and the second volume are dimensioned relative to each other such that: the reduction of the first chamber pressure to less than the first selected pressure causes movement of the first membrane to move the inter-chamber valve member from the closed position to the open position, which exposes the second chamber to the first chamber, thereby reducing the second chamber pressure to less than the second selected pressure.

8. The vehicle vacuum system of claim 7, wherein the second chamber feed conduit includes a check valve that prevents air from flowing from the second chamber through the second chamber feed conduit when the second chamber pressure is higher than the first chamber pressure, and the check valve allows air to flow from the first vacuum source into the second chamber when the first chamber pressure is higher than the second chamber pressure.

9. The vehicle vacuum system of claim 7, wherein the actuator output member is an actuator arm, and wherein the first output member position is a retracted position of the actuator arm relative to the actuator housing, and the second output member position is an extended position of the actuator arm relative to the actuator housing, the actuator arm extending further from the actuator housing in the extended position than in the retracted position.

10. The vehicle vacuum system of claim 7, wherein the first volume is at least 20 times greater than the second volume.

11. The vehicle vacuum system of claim 7, wherein the first membrane external pressure and the second membrane external pressure are both ambient air pressures external to the vacuum actuator.

12. A vacuum actuator for use in a vehicle vacuum system, the vacuum actuator comprising:

an actuator housing comprising a first chamber and a second chamber, wherein the first chamber is at a first chamber pressure, wherein the second chamber has a second chamber pressure;

an actuator output member movable relative to the actuator housing between a first output member position and a second output member position;

a first diaphragm serving as a wall of the first chamber such that a first side of the first diaphragm is exposed to the first chamber pressure and a second side of the first diaphragm is exposed to a first diaphragm external pressure, wherein the first diaphragm is operatively connected to the actuator output member to move the actuator output member to the first output member position;

a second diaphragm serving as a wall of the second chamber such that a first side of the second diaphragm is exposed to the second chamber pressure and a second side of the second diaphragm is exposed to a second diaphragm external pressure, wherein the second diaphragm is operatively connected to the actuator output member to move the actuator output member to the second output member position;

a first diaphragm biasing member positioned to apply a first biasing force to the first diaphragm, wherein the first diaphragm is movable to move the actuator output member from the second output member position to the first output member position by a pressure differential across the first diaphragm that opposes the first biasing force when the first chamber pressure is less than a first selected pressure; and

a second membrane biasing member positioned to apply a second biasing force to the second membrane and the actuator output member to urge the output member toward the second output member position, wherein the second membrane is movable to move the actuator output member from the second output member position to the first output member position by a pressure differential across the second membrane that opposes the second biasing force when the second chamber pressure is less than a second selected pressure,

wherein the first selected pressure is less than the second selected pressure,

wherein the first membrane biasing member has a first spring rate that determines the first selected pressure and the second membrane biasing member has a second spring rate that determines the second selected pressure.

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