CN103216323B - Stroke changing engine stroke switching mechanism - Google Patents

Abstract

The invention discloses a stroke changing engine stroke switching mechanism. Two axial sides of a camshaft are respectively provided with a bearing. A cam body is arranged on the camshaft. The cam body is composed of four cam sheet bodies. A hemispheric locating groove I is formed in a four-stroke operating mode air inlet cam along the direction from the inner circumferential face to the outer circumferential face; a hemispheric locating groove II is formed in a two-stroke operating mode air outlet cam along the direction from the inner circumferential face to the outer circumferential face; a groove hole, namely a guiding groove, with a circular cross section is formed in the camshaft outer circumferential face corresponding to the locating groove I; and a locating steel ball is arranged inside the locating groove and connected with one end of a spring inside the guiding groove and the other end of the spring is connected with the groove bottom of the guiding groove. Compared with the prior art, the stroke changing engine stroke switching mechanism has the advantages that change on a prior machine is small, a valve timing mechanism transmission portion is not changed, adaptability is strong, switching is rapid and stable and weight is light.

Description

A Stroke Switching Mechanism for a Variable Stroke Engine

Technical Field The present invention relates to a switching mechanism, in particular to a stroke switching mechanism for a variable stroke engine.

Background Art Traditional internal combustion engines are divided into four-stroke engines and two-stroke engines, which can only work in specific working modes, and engines with different modes have their own advantages and disadvantages. The ventilation process of four-stroke engines is in two Carried out in different piston strokes, the scavenging loss is less and the residual exhaust gas coefficient after the ventilation is smaller, so it is obviously better than the two-stroke engine in terms of fuel consumption and emissions, but the power performance is worse than the two-stroke engine under heavy load conditions , in order to meet the high power demand of the four-stroke engine when it is overspeeding or climbing a hill, it is necessary to switch the working mode to the two-stroke working mode at this time, so as to realize the , to increase the reserve power of the engine.

The United States patent Two-stroke and Four-stroke Switching Mechanism, patent number US7036465B2, discloses a two-stroke and four-stroke switching mechanism, mainly in the form of double rocker arms, and a four-stroke working mode rocker is integrated on the rocker shaft And the two-stroke working mode rocker arm, there is a connecting part between the two, and there is a center hole for two switching pins to move between the three. The switching pin works under the action of oil pressure. When the four-stroke working mode is required, the four-stroke The rocker arm switching pin enters into operation, connecting the four-stroke rocker arm and the middle part as a whole, and at the same time, the two-stroke rocker arm and the middle part are separated, and enters the four-stroke working mode at this time; when the two-stroke working mode is required, the two-stroke rocker arm switches The pin enters into work, and the two-stroke rocker arm and the middle part are connected as a whole, and the four-stroke rocker arm and the middle part are separated at the same time, and the two-stroke working mode is entered at this time. This mechanism can realize mutual switching between different working modes, but the changes to the original machine are relatively large, the camshaft and the rocker arm must be improved, and the control requirements for switching timing are relatively strict, the control program and oil pressure, oil temperature Any small-scale fluctuations may lead to misjudgment of switching timing, resulting in unsmooth switching.

SUMMARY OF THE INVENTION The object of the present invention is to provide a variable-stroke engine stroke switching mechanism that not only requires little modification to the original machine, does not change the transmission part of the valve mechanism, has strong adaptability, but also has fast and stable switching, small mass, simple processing and low cost. .

The present invention mainly realizes the axial sliding of the cam body on the central shaft of the cam through the electronic control unit controlling the execution of the electromagnetic driver, so as to achieve the switching of the cam under different working modes.

The present invention mainly includes a camshaft, a bearing, a cam body, a fastening screw, a flat key, a positioning steel ball, a spring and a boss. Bearings are arranged on both axial sides of the camshaft, and the camshaft can be moved through two bearings. Cooperate with the bearing seat on the cylinder head of the engine to realize free rotation in the cylinder head; the camshaft is provided with a cam body, which is composed of 4 cam pieces, and they are in the two-stroke working mode in sequence along the axial direction Intake cam, intake cam in four-stroke working mode, exhaust cam in two-stroke working mode and exhaust cam in four-stroke working mode, in which the intake cam in four-stroke working mode and the exhaust cam in four-stroke working mode are single-peak cams, The intake cam in the two-stroke working mode and the exhaust cam in the two-stroke working mode are double-peak cams, and the four cam pieces are connected to the camshaft through a flat key, and the flat key is fixed in the keyway of the camshaft by three screws; Both axial sides of the above-mentioned camshaft are provided with a fastening screw parallel to the axis of the camshaft and inserted into the interior of the four cam pieces in sequence. These two fastening screws are set in reverse to ensure the tight fit of the four cam pieces , internal threads are provided in the cam sheet slots corresponding to the ends of the above two fastening screws, that is, the end of one of the fastening screws inserted by the intake cam in the two-stroke working mode is connected with the exhaust cam in the four-stroke working mode through threads, The end of another fastening bolt inserted by the exhaust cam of the four-stroke working mode is threadedly connected with the intake cam of the two-stroke working mode; The boss I, the cross-section of the boss I is arc-shaped, and its side facing the camshaft head is processed as a helical surface; the side of the four-stroke working mode exhaust cam facing the camshaft tail is provided with a An integrated boss II, the cross section of the boss II is arc-shaped, and its side facing the tail of the camshaft is processed into a helical surface; a hemisphere is set from the inner circumference of the intake cam in the four-stroke working mode to the outer circumference. The shape of the slot is the positioning slot I; the inner circumference of the exhaust cam in the two-stroke working mode is provided with a hemispherical slot in the direction of the outer circumference, that is, the positioning slot II; the diameter of the positioning slot I and the positioning slot II The same; the outer circumference of the camshaft corresponding to the positioning groove I is provided with a circular slot in the camshaft, that is, a guide groove. The centerline of the guide groove is perpendicular to the axis of the camshaft, and the diameter of the guide groove is greater than Or equal to the diameter of the positioning groove I, the positioning steel ball is set inside the positioning groove I, the diameter of the positioning steel ball is smaller than the diameter of the positioning groove I, and the positioning steel ball is connected to one end of the spring inside the guide groove , the other end of the spring is connected with the bottom of the guide groove.

Each of the above-mentioned cam pieces is provided with an oil hole for lubricating oil to pass through, that is, a through hole with a circular cross-section is set from the outer circumferential surface of the intake cam in the two-stroke working mode toward the inner circumferential surface, that is, the oil hole Ⅰ; from the outer peripheral surface of the intake cam in the four-stroke working mode, a through hole with a circular cross-section is set in the direction of the inner peripheral surface, that is, the oil hole II, and the extending end of the oil hole II is in contact with the groove of the positioning groove I. Connected to the bottom; from the outer peripheral surface of the two-stroke working mode exhaust cam to the inner peripheral surface, a through hole with a circular cross-section is set, that is, the oil hole III, and the extending end of the oil hole III is connected to the positioning groove II. The groove bottoms are connected; a through hole with a circular cross-section is set from the outer circumferential surface of the four-stroke working mode exhaust cam to the inner circumferential surface, that is, the oil hole IV.

On both sides of the guide groove, one end is connected to the outer peripheral surface of the camshaft, and the other end is connected to the central axis hole of the camshaft. A strip-shaped through hole, namely oil hole V and oil hole VI, the oil hole V is connected to the oil hole I is connected, and the centerline distance between oil hole V and oil hole VI is equal to the centerline distance between oil hole I and oil hole III, and the centerline distance between oil hole V and oil hole VI is equal to the centerline distance between oil hole II and oil hole The center line distance of oil hole IV ensures that oil hole V communicates with oil hole I in four-stroke working mode, oil hole VI communicates with oil hole III, and oil hole V communicates with oil hole II in two-stroke working mode. Hole VI communicates with oil hole IV.

The cam body of the present invention is connected with the camshaft through the connection mode of the flat key, which can not only realize the rotation of the cam body following the camshaft, but also realize the sliding of the cam body along the axial direction, and the cam body is realized by controlling the electromagnetic driver by the electronic control unit Axially slide on the camshaft to switch between the four-stroke working mode and the two-stroke working mode. The electromagnetic driver mainly acts on the cam pieces at both ends of the cam body, that is, the intake cam in the two-stroke working mode and the exhaust cam in the four-stroke working mode. , further, the electromagnetic driver directly acts on the bosses on the cam pieces at both ends, so that the rotating cam body slides as a whole, and realizes the switching between the two working modes. The positioning groove, positioning steel ball and spring realize the positioning to ensure the smooth completion of the work; the oil hole for lubricating oil to pass through is processed on the cam body and the central shaft, and the oil hole of the cam body corresponds to the hemispherical positioning groove, which can play a role in lubrication and The dual role of positioning.

Compared with the prior art, the present invention has the following advantages:

1. There is no need to change the transmission part of the gas distribution mechanism, only the structure of the gas distribution cam needs to be improved, and it can be realized by adding an electromagnetic drive control part in the gas distribution chamber. The structure is simple and the original machine has little change;

2. The driving part of the valve mechanism has flexible configuration and good adaptability. The switching cam can drive both the rocker arm and the valve tappet directly;

3. The increase in the number and quality of parts is small, and it is easy to realize light weight. Compared with the original machine, this solution only has more small parts such as electromagnetic drives, and the increase in mass is small, which can greatly increase the specific mass power of the variable stroke machine;

4. Do not change the original design value of single-stroke valve timing;

5. The cam body adopts the combination form of the plate body, and the cam plate body can be replaced, which facilitates the correction of the gas distribution phase by the method of combining theory and practice, shortens the experimental cycle, reduces the cost of the experiment, and makes it difficult to The processing of the formed cam body becomes simple and easy;

6. The switching boss of the cam body adopts a helical surface, which makes the switching of the stroke fast and smooth, and the range of the switching boss ensures that the electromagnetic driver has enough time margin to execute, reducing the requirements for the electromagnetic driver .

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic cross-sectional front view of the present invention.

Fig. 2 is a diagram of A-A of Fig. 1 .

Fig. 3 is a schematic left view of the intake cam in the two-stroke working mode of the present invention.

Fig. 4 is a schematic top view of the intake cam in the two-stroke working mode of the present invention.

Fig. 5 is a schematic right view of the exhaust cam in the four-stroke working mode of the present invention.

Fig. 6 is a schematic bottom view of the exhaust cam in the four-stroke working mode of the present invention.

Fig. 7 is a schematic diagram of the working state of the present invention.

Specific embodiments As shown in Figure 1 and Figure 2, bearings 2 are provided on both axial sides of the camshaft 1, and a cam body 3 is provided on the camshaft. The cam body is composed of 4 cam pieces. Along the axial direction, there are two-stroke working mode intake cam 4, four-stroke working mode intake cam 5, two-stroke working mode exhaust cam 6 and four-stroke working mode exhaust cam 7, wherein the four-stroke working mode intake cam and The exhaust cams in the four-stroke working mode are single-peak cams, the intake cams in the two-stroke working mode and the exhaust cams in the two-stroke working mode are double-peak cams, and the four cam pieces are connected to the camshaft through the flat key 8, and The flat key is fixed in the keyway of the camshaft through three screws 9; the axial sides of the above-mentioned camshaft are provided with a fastening screw 10 which is parallel to the axis of the camshaft and inserted into the inside of the four cam pieces in sequence. The fastening screws are set in reverse. In order to ensure the tight fit of the four cam pieces, internal threads are provided in the cam piece slots corresponding to the ends of the above two fastening screws, one of which is inserted by the two-stroke working mode intake cam The end of the fastening screw is threaded to the exhaust cam in the four-stroke working mode, and the end of another fastening bolt inserted by the exhaust cam in the four-stroke working mode is threaded to the intake cam in the two-stroke working mode; The gas cam is provided with a boss 11 connected with it toward the side of the camshaft head; the exhaust cam of the four-stroke working mode is provided with a boss 12 connected with it toward the side of the camshaft tail; The inner circumference of the four-stroke working mode intake cam is provided with a hemispherical slot in the direction of the outer circumference, i.e. positioning groove 13; the inner circumference of the exhaust cam in the two-stroke mode is provided with a hemispherical slot in the direction of the outer circumference. , i.e. the positioning groove 14; the diameter of the positioning groove 13 is the same as that of the positioning groove 14; the outer circumference of the camshaft corresponding to the positioning groove 13 faces the inside of the camshaft to establish a circular slot in section, i.e. the guide groove 15, the The center line of the guide groove is perpendicular to the axis of the camshaft, and the diameter of the guide groove is greater than the diameter of the positioning groove 13, and the positioning steel ball 16 is set inside the positioning groove 13, and the diameter of the positioning steel ball is smaller than the positioning groove 13 diameter, and the positioning steel ball is connected to one end of the spring 17 inside the guide groove, and the other end of the spring is connected to the groove bottom of the guide groove; an oil hole for lubricating oil to pass through is provided on each of the above-mentioned cam pieces , that is, a circular through-hole, i.e. an oil hole 18, is set by the outer circumference of the intake cam in the two-stroke working mode toward the inner circumference; i.e., the oil hole 18; In the face direction, a through hole with a circular cross section is set, that is, an oil hole 19, and the extending end of the oil hole 19 is connected with the groove bottom of the positioning groove 13; The direction of the circumferential surface is provided with a through hole with a circular cross section, i.e. an oil hole 20, and the extending end of the oil hole 20 is connected to the groove bottom of the positioning groove 14; The direction of the inner circumferential surface is provided with a circular through hole in section, i.e. an oil hole 21; The outer circumferential surface is connected, and the other end is connected to the strip-shaped through hole of the central shaft hole of the camshaft, that is, the oil hole 23 and the oil hole 22; the oil hole 23 is connected with the oil hole 18, and the oil hole 23 is connected with the oil hole 22 The centerline distance between the oil holes 18 and 20 is equal to the centerline distance between the oil hole 18 and the oil hole 20, and the centerline distance between the oil hole 23 and the oil hole 22 is equal to the centerline distance between the oil hole 19 and the oil hole 21.

Figures 1 and 2 show that the engine is in the four-stroke working mode. At this time, the positioning steel ball 16 enters the positioning groove 13 under the action of the spring 17 to realize the limit, and avoids the occurrence of the cam body working in the four-stroke working mode. Axial movement, and the oil hole 23 communicates with the oil hole 18 to achieve dual functions of lubrication and positioning; when the working mode needs to be switched to the two-stroke working mode, the cam body 3 slides to the left as a whole, and the positioning steel ball 16 is positioned on the cam body 3 Return to the guide groove 15 under the extrusion force of the leftward movement. After entering the two-stroke working mode, the positioning steel ball 16 enters the positioning groove 14 under the action of the spring 17 to realize the limit position, and again prevent the cam body 3 from moving in the two-stroke mode. In the working mode, axial sliding occurs during work, and the oil hole 22 communicates with the oil hole 19, and the oil hole 23 communicates with the oil hole 21, so as to realize the dual functions of lubrication and positioning.

As shown in Fig. 3 and Fig. 4, the intake cam 4 in the two-stroke working mode is provided with a boss 11 integrally connected with it toward the side of the camshaft head. The side of the head is machined as a helicoid.

As shown in Fig. 5 and Fig. 6, the exhaust cam 7 of the four-stroke working mode is provided with a boss 12 integrally connected with it toward the side of the camshaft tail. The side surface of the shaft tail is machined as a helical surface.

As shown in Figure 7, the switching lever 25 of the electromagnetic driver 24 corresponds to the boss 12 of the four-stroke working mode exhaust cam 7, and the switching lever 27 of the electromagnetic driver 26 corresponds to the boss 11 of the intake cam 4 of the two-stroke working mode, Both the electromagnetic driver 24 and the electromagnetic driver 26 are installed on the cylinder head of the engine, and are controlled by an electronic control unit 28 . When working, switch from the four-stroke working mode to the two-stroke working mode, the electromagnetic driver 24 is executed under the control of the electronic control unit 28, and the switching lever 25 starts to move. Under the force of the table 12, the cam body 3 moves to the left along the axial direction and enters the two-stroke working mode, and the cam enters the working state in the two-stroke working mode; when the electronic control unit issues a control switch from the two-stroke working mode to the four-stroke working When the signal is activated, the electromagnetic driver 26 is executed under the control of the electronic control unit 28, and the switch lever 27 starts to move. With the axial rotation of the cam body 3, under the force of the switch lever 27 on the boss 11, the cam body 3 moves along the axis. Move to the right to enter the four-stroke working mode, and the cam in the four-stroke working mode enters the working state.

Claims (3)

1. A variable stroke engine stroke switching mechanism, comprising camshaft, bearing, cam body, fastening screw, flat key, positioning steel ball, spring and boss, is characterized in that: the axial two ends of described camshaft are There is a bearing, and a cam body is set on the camshaft. The cam body is composed of 4 cam pieces. They are the intake cam in the two-stroke working mode, the intake cam in the four-stroke working mode, and the two-stroke working mode in the axial direction. Exhaust cams and four-stroke working mode exhaust cams, in which four-stroke working mode intake cams and four-stroke working mode exhaust cams are single-peak cams, and two-stroke working mode intake cams and two-stroke working mode exhaust cams are both It is a double-peak cam, the four cam pieces are connected with the camshaft through flat keys, and the flat keys are fixed in the key groove of the camshaft through three screws; there is a camshaft parallel to the axis of the camshaft on both sides of the camshaft. And insert the four fastening screws inside the cam body in sequence, and set internal threads in the cam body slots corresponding to the ends of the above two fastening screws, that is, one of the fastening screws inserted by the intake cam in the two-stroke working mode The end is threaded to the exhaust cam in the four-stroke working mode, and the other end of the fastening screw inserted by the exhaust cam in the four-stroke working mode is threaded to the intake cam in the two-stroke working mode; the intake cam in the two-stroke working mode The side facing the camshaft head is provided with a boss I connected with it. The section of the boss I is arc-shaped, and the side facing the camshaft head is processed as a helical surface; the four-stroke working mode exhaust The side of the cam facing the end of the camshaft is provided with a boss II which is integrated with it. The inner circumference of the intake cam is provided with a hemispherical slot in the direction of the outer circumference, i.e. the positioning slot I; the inner circumference of the exhaust cam in the two-stroke working mode is provided with a hemispherical slot in the direction of the outer circumference, i.e. the positioning slot II; the diameter of the positioning groove I is the same as that of the positioning groove II; the outer circumference of the camshaft corresponding to the positioning groove I faces the inside of the camshaft to set a circular slot, that is, a guide groove, and the center line of the guide groove perpendicular to the axis of the camshaft, and the diameter of the guide groove is greater than or equal to the diameter of the positioning groove I, the positioning steel ball is set inside the positioning groove I, and the diameter of the positioning steel ball is smaller than the diameter of the positioning groove I, and The positioning steel ball is connected with one end of the spring inside the guide groove, and the other end of the spring is connected with the groove bottom of the guide groove. 2. The variable-stroke engine stroke switching mechanism according to claim 1, characterized in that: the outer circumferential surface of the intake cam in the two-stroke working mode is provided with a circular through hole in the direction of the inner circumferential surface, that is, an oil hole Ⅰ; from the outer peripheral surface of the intake cam in the four-stroke working mode, a through hole with a circular cross-section is set in the direction of the inner peripheral surface, that is, the oil hole II, and the extending end of the oil hole II is in contact with the groove of the positioning groove I. Connected to the bottom; from the outer peripheral surface of the two-stroke working mode exhaust cam to the inner peripheral surface, a through hole with a circular cross-section is set, that is, the oil hole III, and the extending end of the oil hole III is connected to the positioning groove II. The groove bottoms are connected; a through hole with a circular cross-section is set from the outer circumferential surface of the four-stroke working mode exhaust cam to the inner circumferential surface, that is, the oil hole IV. 3. The variable-stroke engine stroke switching mechanism according to claim 2, characterized in that: the two sides of the guide groove are respectively provided with a strip shape with one end connected to the outer peripheral surface of the camshaft and the other end connected to the central shaft hole of the camshaft. Through holes, that is, oil hole V and oil hole VI, the oil hole V is connected to the oil hole I, and the centerline distance between the oil hole V and the oil hole VI is equal to the centerline of the oil hole I and the oil hole III The centerline distance between the oil hole V and the oil hole VI is equal to the centerline distance between the oil hole II and the oil hole IV.

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