JPH07189633A - Variable valve device for internal combustion engine - Google Patents

Abstract

(57) [Summary] [Purpose] Both the lift amount and valve opening timing of the intake / exhaust valve 2 can be variably controlled at the same time. [Structure] The cam side plunger 7 is driven by a cam shaft 10 and pressurizes the hydraulic oil in the main hydraulic chamber 9. The intake / exhaust valve 2 is pushed open by the hydraulic pressure in the main hydraulic chamber 9. Between the main hydraulic chamber 9 and the accumulator 11 on the low pressure side,
The release valve 21 is interposed, and the lift amount is variably controlled by opening the valve during the lift. A piston 42 is slidably arranged in the sub cylinder 41 to form a pressure absorption chamber 43 communicating with the main hydraulic chamber 9. The initial position of the piston 42 is determined by the balance between the engine lubricating oil pressure received from the pressure absorption chamber 43 side and the biasing force of the return spring 48. When the cam lift starts, the amount of the pressurized hydraulic oil corresponding to the initial position of the piston 42 is absorbed in the pressure absorption chamber 43, so that the opening of the intake / exhaust valve 2 is delayed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake valve or an exhaust valve of an internal combustion engine (hereinafter, both are collectively referred to as intake and exhaust valves).
The present invention relates to a variable valve operating device for an internal combustion engine that variably controls the lift amount and the valve opening timing of the engine.

[0002]

2. Description of the Related Art A hydraulic variable valve operating device for variably controlling the lift amount of intake and exhaust valves of an internal combustion engine is disclosed in, for example, Japanese Patent Laid-Open No. 58-5.
It is disclosed in Japanese Patent No. 3615. This device pressurizes the hydraulic oil along the cam lift by reciprocating the cam side plunger by the cam shaft, and hydraulically drives the intake / exhaust valve by the pressurized hydraulic oil. A release valve that releases the pressurized hydraulic oil to the low pressure side is provided in the hydraulic oil supply path. If the release valve is opened during the lift of the intake / exhaust valve, the pressure of the hydraulic oil decreases, so that the intake / exhaust valve switches to the seating operation from the midpoint of the lift due to the urging force of the valve spring. That is, the lift amount of the intake / exhaust valve can be variably controlled by the opening timing of the release valve.

Further, Japanese Patent Laid-Open No. 62-38812 discloses a hydraulic variable valve actuating device which variably controls the opening timing of an exhaust valve by utilizing combustion pressure in a cylinder. There is. This device has a structure in which a pressure accumulator is provided in the pressurized hydraulic oil supply path from the cam side plunger to the intake / exhaust valve side plunger, and the piston that defines the oil chamber of the pressure accumulator is provided with a spring. Power is acting. Therefore, when the hydraulic oil is pressurized by the cam-side plunger, the hydraulic oil first flows into the oil chamber of the pressure accumulator to accumulate pressure, and then rises to the pressure required to lift the exhaust valve. ,
The exhaust valve begins to lift. That is, the opening timing of the exhaust valve is delayed accordingly. Since the cylinder internal pressure is higher in the higher load range, the valve opening pressure required to lift the exhaust valve becomes higher, and accordingly, more hydraulic oil is accumulated until it balances with the reaction force of the spring of the pressure accumulator. Flow into. Therefore, the valve opening timing changes according to the load.

[0004]

However, with the structure for releasing the pressure during the lift as disclosed in Japanese Patent Laid-Open No. 58-53615, it is impossible to variably control the valve opening timing by itself. Therefore, it is not possible to sufficiently meet various demands. In order to control the valve opening timing with this device, it is necessary to combine it with a mechanism that changes the phase of the cam with respect to the crankshaft, and this complicates the configuration.

Further, in the structure of Japanese Patent Laid-Open No. 62-38812, the combustion pressure in the cylinder is used, so that it cannot be applied to an intake valve having a low cylinder pressure when the valve is opened. Further, even when applied to an exhaust valve, the cylinder internal pressure at the time of valve opening varies considerably between cylinders or cycles, so the valve opening timing tends to become unstable, and the degree of freedom in control is low.

[0006]

A variable valve operating system for an internal combustion engine according to the present invention is driven by an intake valve or an exhaust valve which is constantly urged in a closing direction by a valve spring, a camshaft, and a hydraulic oil. The cam side plunger that pressurizes and the valve side plunger that operates to one side by the hydraulic oil pressurized by the cam side plunger to lift the intake valve or the exhaust valve, and the hydraulic oil pressurized by the cam side plunger Is separated by a release valve that opens to the side and a piston that is slidably arranged in the sub-cylinder,
Also, a pressure absorption chamber into which the hydraulic oil pressurized by the cam side plunger can flow, and a piston position variable setting means for variably setting the initial position of the piston during a period in which the cam side plunger does not pressurize the hydraulic oil. And are provided.

According to the second aspect of the invention, the piston position variable setting means applies the lubricating oil pressure of the internal combustion engine to the piston so as to urge the piston to one side, and the piston oil pressure is opposed to the lubricating oil pressure. Is provided with a return spring so as to bias the other side toward the other side.

According to the third aspect of the invention, the piston position variable setting means applies a control hydraulic pressure adjusted to a desired pressure to the piston so as to bias the piston to one side, and the control hydraulic pressure is also applied. A return spring is provided so as to oppose the piston and urge the piston toward the other side.

Further, in the invention of claim 4, the piston position variable setting means comprises a solenoid for urging the piston toward one side and a return spring for urging the piston toward the other side.

[0010]

When the cam side plunger is pressed by the cam shaft, the hydraulic pressure in the hydraulic path to the valve side plunger increases, and the valve side plunger moves accordingly. That is,
The intake / exhaust valve lifts according to the hydraulic pressure. If the release valve opens during this lift, the pressure of the hydraulic oil that has been pressurized is released to the low pressure side, so the intake and exhaust valves switch to a seating operation during the lift. Therefore, the lift amount changes by changing the opening timing of the release valve.

On the other hand, the initial position of the piston in the sub-cylinder is held at an appropriate position by the piston position variable setting means. In this state, when the cam side plunger is pressed as described above and the hydraulic pressure of the hydraulic oil increases, a part of the hydraulic oil flows into the pressure absorption chamber. During this time, the increase in hydraulic pressure is substantially suppressed. The amount of inflow into the pressure absorption chamber changes depending on the initial position of the piston. When the piston moves to the limit due to the pressure of the hydraulic oil that has flowed in, the hydraulic oil cannot flow any further, so the hydraulic pressure increases with the operation of the cam side plunger, and the lift of the intake and exhaust valves starts. Further, when the hydraulic pressure of the hydraulic oil decreases with the opening of the release valve or the end of the cam lift, the piston returns to the initial position. That is, the valve opening timing of the intake / exhaust valve is delayed by the pressure absorption chamber, and the delay amount, that is, the valve opening timing can be variably controlled by variably controlling the initial position of the piston in the sub cylinder.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a sectional view of an essential part of an internal combustion engine showing a first embodiment of the present invention, in which an intake / exhaust valve 2 is slidably mounted on a cylinder head 1 and a valve spring 3 is used. Always biased in the closing direction. A housing 4 of the lift control unit is superposed on the upper surface of the cylinder head 1, and a valve side plunger 6 is slidably fitted in a cylinder hole 5 formed in the lower surface of the housing 4. . The tip of this valve side plunger 6 is
The intake / exhaust valve 2 is pushed open by contacting the stem end of the intake / exhaust valve 2 and moving the plunger 6 by hydraulic pressure.

A cam side plunger 7 is slidably arranged in a cylinder hole 8 on the upper surface of the housing 4. The cam side plunger 7 and the valve side plunger 6
And share the main hydraulic chamber 9. That is, the cam side plunger 7 is adapted to be driven via the rocker arm 16 by the cam 10a of the cam shaft 10 which rotates in synchronization with the crank shaft (not shown) of the internal combustion engine. By rotating, it reciprocates and pressurizes the hydraulic oil in the main hydraulic chamber 9. The valve side plunger 6 is pressed by the hydraulic pressure in the lift direction of the intake / exhaust valve 2.

An accumulator 11 is provided in the main hydraulic chamber 9.
Is supplied with hydraulic oil from the check valve 12 through the check valve 12. The accumulator 11 communicates with the discharge side of an oil pump (not shown) through the check valve 13 and the hydraulic pressure introduction hole 17. It should be noted that this hydraulic system is integrated with the engine lubricating system, and the engine lubricating oil is used as the working oil and the oil pump for lubrication that is mechanically driven by the engine output is also used as it is. That is, when the cam 10 a is not lifted, the check valves 12, 13 are provided in the main hydraulic chamber 9.
Lubricating oil pressure is introduced via.

Further, in order to variably control the lift amount of the intake / exhaust valve 2 in accordance with operating conditions and the like, a release valve 21 is arranged between the main hydraulic chamber 9 and the accumulator 11 on the low pressure side. That is, the hydraulic circuit 15 is provided in parallel with the hydraulic circuit 14 including the check valve 12, and the release valve 21 is provided in the hydraulic circuit 15. This release valve 21
Is a solenoid valve that opens and closes ON and OFF, and is composed of a valve body 22 that opens and closes the hydraulic circuit 15, and a solenoid 23 that biases the valve body 22 in its seating direction by magnetic force. That is, when the solenoid 23 is energized, the hydraulic circuit 15 is closed, and communication with the low pressure side is blocked. Then, when the energization of the solenoid 23 is stopped, the hydraulic pressure in the main hydraulic chamber 9 is released to the accumulator 11. Therefore, if the energization of the release valve 21 is stopped while the intake / exhaust valve 2 is being lifted by the pressurized hydraulic oil in the main hydraulic chamber 9, the hydraulic pressure acting on the valve-side plunger 6 is lowered, and the intake / exhaust gas is exhausted. The valve 2 shifts to a sitting motion during the lift. Therefore, the lift amount can be variably controlled by variably controlling the power supply stop timing of the solenoid 23 for each cycle.

On the side surface of the housing 4, a large diameter portion 4 is provided.
A sub-cylinder 41 having 1a and a small diameter portion 41b is provided, and a piston 42 is slidably accommodated therein. The piston 42 is the large diameter portion 4 of the sub cylinder 41.
1a, and a small diameter portion 42b that fits in the small diameter portion 41b of the sub-cylinder 41, and a small diameter portion 42a.
The pressure absorbing chamber 43 is defined in the sub cylinder 41 by the front end surface b. The pressure absorption chamber 43 is always in communication with the main hydraulic chamber 9 via the communication hole 44. Elastic bodies 45 such as rubber are attached to the front and rear ends of the large diameter portion 41b of the sub-cylinder 41 in order to cushion the piston 42 and to prevent collision noise. Further, a thin communication hole 47 is formed through the large diameter portion 42a of the piston 42 so that the annular chamber 46 (see FIG. 3) generated on the small diameter portion 41b side of the large diameter portion 41a is not closed. A return spring 48 for urging the piston 42 in the contracting direction of the pressure absorbing chamber 43 is provided on the rear side of the large diameter portion 42a of the piston 42. Incidentally, 49 is an air hole. In this embodiment, the lubricating oil pressure acting from the pressure absorbing chamber 43 side of the piston 42 and the return spring 48 constitute the piston position variable setting means. That is, the piston 42 is urged to one side by the lubricating oil pressure acting from the pressure absorption chamber 43 side, and the piston 42 is urged to the other side so as to face the piston 42, so that both are balanced. The initial position of the piston 42 is set to the position.

In the structure provided with the pressure absorbing chamber 43 as described above, when the pressure in the main hydraulic chamber 9 is increased with the lift of the cam 10a, the same pressure is applied to the piston 42.
Act on. Since the biasing force of the return spring 48 of the piston 42 is smaller than the pressure required to lift the intake / exhaust valve 2, the hydraulic pressure causes the piston 42 to move in the expansion direction of the pressure absorption chamber 43. Along with this, the pressurized hydraulic oil in the main hydraulic chamber 9 flows into the pressure absorption chamber 43,
During that time, the pressure rise of the hydraulic oil is substantially suppressed, and the intake / exhaust valve 2 does not lift. Then, when the piston 42 moves to the limit, the inflow into the pressure absorption chamber 43 is stopped, so that the pressure of the pressurized hydraulic oil rises again and the lift of the intake / exhaust valve 2 starts. That is, due to the action of the pressure absorption chamber 43, the lift start of the intake / exhaust valve 2, that is, the valve opening timing is determined by the cam 10.
It will be later than the start of the lift of a.

The amount of delay in opening the intake / exhaust valve 2 is determined by the amount of oil that can flow into the pressure absorption chamber 43. As described above, the engine lubricating oil pressure is introduced into the pressure absorption chamber 43 during the period when the cam side plunger 7 is not pressurizing the operating oil. As shown, the initial position of the piston 42 is on the right side of FIG. 2, and the pressure absorption chamber 43 is in a relatively contracted state. Therefore, the amount of oil that can be absorbed before the piston 42 moves to the limit is relatively large. Therefore, the delay in opening the intake / exhaust valve 2 becomes large.

On the other hand, when the lubricating oil pressure is high, the initial position of the piston 42 is as shown in FIG.
The pressure absorption chamber 43 is in a relatively expanded state. Therefore, the amount of oil that can be absorbed before the piston 42 moves to the limit is relatively small. Therefore, the delay in opening the intake / exhaust valve 2 is reduced.

Further, the lubricating oil pressure of the internal combustion engine becomes high (almost constant due to the valve opening pressure of a relief valve (not shown)) as the engine speed increases, so that it is as shown in FIG. In this case, the delay in opening the valve is large and the delay in opening the valve is reduced in the high speed region of the engine as shown in FIG.

Then, after the intake / exhaust valve 2 starts to open, at an appropriate point during the lift, as described above, the release valve 2 is opened.
If the energization of the solenoid 23 of No. 1 is stopped, the intake / exhaust valve 2 will start a seating operation at that time, and the lift amount can be arbitrarily controlled. Although the pressurized hydraulic oil is released to the accumulator 11 on the low pressure side in the illustrated example, it may be released to the atmospheric pressure. However, if it is released to the accumulator 11 as in the above embodiment, the pressure energy of the hydraulic oil can be recovered, which is advantageous in terms of the combustion consumption rate.

This embodiment can be applied to either the intake valve or the exhaust valve as the intake / exhaust valve 2.

That is, if this variable valve operating device is applied to the intake valve side, the valve opening timing of the intake valve is relatively advanced in the high engine speed region as shown in the valve lift characteristic in FIG.
The valve overlap with the exhaust valve becomes large, which is advantageous in increasing the output. On the contrary, in the engine low speed range, the valve opening timing of the intake valve is relatively delayed, so that the valve overlap is reduced and the combustion can be stabilized. The broken line in FIG.
An example of characteristics when the lift amount is variably controlled by the release valve 21 is shown.

On the other hand, when the exhaust valve opening timing is early when the engine speed is low, exhaust loss increases and residual gas increases.
If the variable valve operating device of this embodiment is applied to drive an exhaust valve, the valve opening timing of the exhaust valve can be relatively delayed in the low speed range, and fuel consumption and emission can be improved. Further, in the high speed region of the engine, the opening timing of the exhaust valve is relatively early, which is advantageous for gas exchange.

Next, FIGS. 5 and 6 show a second embodiment of the present invention.
In the embodiment, only the sub-cylinder 41 portion forming the pressure absorption chamber 43 is shown. The rest of the structure is the same as that of the first embodiment shown in FIG.

In this embodiment, an annular hydraulic chamber 51 is formed between the sub-cylinder 41 and the large diameter portion 42a of the piston 42, more specifically, in the outer peripheral portion of the small diameter portion 42b, where the hydraulic pressure supply port is provided. A control oil pressure is introduced from the outside via 52. As this control hydraulic pressure, a pressure obtained by adjusting the hydraulic pressure from a hydraulic pressure source (oil pump for engine lubrication or another oil pump) to a desired pressure with a hydraulic control valve such as a relief valve or a duty control valve is used. That is, in this embodiment, in addition to the engine lubricating oil pressure acting from the pressure absorption chamber 43, the piston 42 is urged to one side by the control oil pressure, and the urging force of the return spring 48 acts so as to oppose this. And these constitute a piston position variable setting means.

In this embodiment, when the control oil pressure is low, the initial position of the piston 42 is determined as shown in FIG. 5, and the amount of oil that can be absorbed is relatively large. Therefore, the delay in opening the intake / exhaust valve 2 becomes large.

On the other hand, when the control oil pressure is high, the initial position of the piston 42 is determined as shown in FIG. 6, and the amount of oil that can be absorbed is relatively small. Therefore, the delay in opening the intake / exhaust valve 2 is reduced.

As described above, in the second embodiment, the valve opening delay amount can be freely variably controlled by the control hydraulic pressure, and the degree of freedom of control is increased. Therefore, this structure can be applied to either the intake valve or the exhaust valve. In addition to the control oil pressure, the initial position of the piston 42
As described above, the influence of the lubricating oil pressure is also exerted, but by appropriately setting the pressure receiving area and the like, the influence can be reduced, and the position of the piston 42 can be controlled substantially only by the control oil pressure. On the contrary, it is possible to set the pressure receiving area and the like so that the influence of the lubricating oil pressure becomes large. In that case, as in the first embodiment described above, the valve opening delay increases as the speed decreases. It has characteristics.

Next, FIGS. 7 and 8 show a third embodiment of the present invention.
In the embodiment, only the sub-cylinder 41 portion forming the pressure absorption chamber 43 is shown. The rest of the structure is the same as that of the first embodiment shown in FIG.

In this embodiment, an auxiliary hydraulic chamber 61 is separated by a large diameter portion 42a of the piston 42 so as to face the pressure absorbing chamber 43, and the auxiliary hydraulic chamber 61 is supplied with a hydraulic pressure supply port 62 for engine lubrication. The hydraulic pressure or the control hydraulic pressure described above is introduced. The return spring 48 is arranged so as to face the hydraulic pressure of the auxiliary hydraulic chamber 61, that is, to bias the piston 42 in the direction in which the pressure absorbing chamber 43 expands. The space around the small diameter portion 42b in which the return spring 48 is housed is open to the atmosphere via the air hole 63.

In this embodiment, when the hydraulic pressure introduced into the auxiliary hydraulic chamber 61 is high, the initial position of the piston 42 is determined as shown in FIG. 7, and the amount of oil that can be absorbed is relatively large. Therefore, the delay in opening the intake / exhaust valve 2 becomes large.

On the other hand, when the hydraulic pressure introduced into the auxiliary hydraulic chamber 61 is low, the initial position of the piston 42 is determined as shown in FIG. 8, and the amount of oil that can be absorbed is relatively small. Therefore, the delay in opening the intake / exhaust valve 2 is reduced.

Therefore, when the engine lubricating oil pressure is introduced into the auxiliary oil pressure chamber 61, the valve opening delay becomes large in the high speed region as shown in FIG. 7 and the valve opening delay becomes as shown in FIG. 8 in the low speed region. Get smaller. Further, when the control oil pressure is used, the degree of freedom in control is increased as in the second embodiment described above.

Incidentally, when the initial position of the piston 42 is set, the lubricating oil pressure is also acting from the pressure absorbing chamber 43 side, but the pressure receiving area for this pressure absorbing chamber 43 is smaller than that on the auxiliary hydraulic chamber 61 side. Therefore, in this embodiment, as the piston position variable setting means, the initial position of the piston 42 is determined mainly by the relationship between the hydraulic pressure on the auxiliary hydraulic chamber 61 side and the biasing force of the return spring 48.

This embodiment is basically applicable to either the intake valve or the exhaust valve. However, when introducing the engine lubricating oil pressure into the auxiliary oil pressure chamber 61, the engine speed as described above is used. It is suitable for driving an exhaust valve of a two-cycle diesel engine from the viewpoint of the characteristics.

Next, FIG. 9 shows a fourth embodiment of the present invention, particularly the sub cylinder 4 forming the pressure absorbing chamber 43.
Only one part is shown. The other parts are shown in FIG.
The configuration is the same as that of the first embodiment.

In this embodiment, the solenoid 71 is used as the piston position variable setting means. That is, in this embodiment, the piston 42 made of a magnetic material has a simple columnar shape, and the tip end surface of the piston 42 separates the pressure absorption chamber 43 from the piston 42. The return spring 48 is arranged so as to bias the. And this piston 4
A solenoid 71 is arranged so as to surround 2 and urges the piston 42 in the expansion direction of the pressure absorption chamber 43 by the magnetic force generated according to the electric current. Therefore, the solenoid 71 and the return spring 48 constitute a piston position variable setting means, and the solenoid 7
The initial position of the piston 42 can be arbitrarily variably controlled by the current applied to the piston 1.

Also in this embodiment, it is possible to secure a high degree of freedom of control, and it is possible to appropriately delay the opening timing of the intake / exhaust valve 2 according to operating conditions.

[0041]

As is apparent from the above description, according to the present invention, both the opening timing and the lift amount of the intake / exhaust valve can be variably controlled at the same time, and the valve more suitable for engine operating conditions can be obtained. Lift characteristics can be obtained. In particular, since the valve opening delay amount can be variably controlled without depending on the unstable combustion pressure, it is possible to suppress the variation between the cylinders and the variation for each cycle and to perform the stable control.

If the initial position of the piston is set by the engine lubricating oil pressure as in the second aspect, the valve opening timing control according to the engine speed can be realized with a simple structure.

If the control oil pressure adjusted to a desired pressure is used as in the third aspect, the degree of freedom of control is increased,
It is possible to realize the valve opening timing control according to various requirements.

If a solenoid is used as in claim 4,
The initial piston position can be easily controlled to a desired position, and the degree of freedom in control is similarly increased.

[Brief description of drawings]

FIG. 1 is a sectional view showing a first embodiment of a variable valve operating device according to the present invention.

FIG. 2 is an enlarged sectional view of an essential part showing a piston initial position when the lubricating oil pressure is low.

FIG. 3 is an enlarged sectional view of an essential part showing a piston initial position when the lubricating oil pressure is high.

FIG. 4 is a valve lift characteristic diagram when the first embodiment is applied to an intake valve.

FIG. 5 is a sectional view showing an essential part of the second embodiment and showing an initial piston position when the control oil pressure is low.

FIG. 6 is a sectional view showing an essential part of the second embodiment and showing a piston initial position when the control oil pressure is high.

FIG. 7 is a cross-sectional view showing an essential part of the third embodiment and showing an initial piston position when the hydraulic pressure in the auxiliary hydraulic chamber is high.

FIG. 8 is a sectional view showing an essential part of the third embodiment and showing an initial piston position when the hydraulic pressure in the auxiliary hydraulic chamber is low.

FIG. 9 is a sectional view showing an essential part of the fourth embodiment.

[Explanation of symbols]

 2 ... Intake / exhaust valve 3 ... Valve spring 6 ... Valve side plunger 7 ... Cam side plunger 9 ... Main hydraulic chamber 11 ... Accumulator (low pressure side) 21 ... Release valve 41 ... Sub cylinder 42 ... Piston 43 ... Pressure absorption chamber 48 ... Return Spring 51 ... Annular hydraulic chamber 61 ... Auxiliary hydraulic chamber 71 ... Solenoid

Claims (4)

[Claims] 1. An intake valve or an exhaust valve which is constantly biased in a closing direction by a valve spring, a cam side plunger which is driven by a cam shaft and pressurizes hydraulic oil, and hydraulic oil which is pressurized by the cam side plunger. Valve side plunger that moves to one side by the above to lift the intake valve or exhaust valve, a release valve that releases the hydraulic oil pressurized by the cam side plunger to the low pressure side, and a slidable arrangement in the sub cylinder The pressure absorption chamber, which is separated by the piston and allows the hydraulic oil pressurized by the cam side plunger to flow in, and the initial position of the piston that is variable while the cam side plunger does not pressurize the hydraulic oil. A variable valve operating device for an internal combustion engine, comprising: a piston position variable setting means for setting. 2. The piston position variable setting means applies a lubricating oil pressure of the internal combustion engine to the piston so as to urge the piston to one side, and opposes the lubricating oil pressure to the other side. 2. The variable valve operating system for an internal combustion engine according to claim 1, wherein the return spring is provided. 3. The piston position variable setting means applies to the piston a control oil pressure adjusted to a desired pressure so as to urge the piston to one side, and the piston is opposed to the control oil pressure. 2. The variable valve operating system for an internal combustion engine according to claim 1, wherein a return spring is provided so as to bias the other. 4. The internal combustion engine according to claim 1, wherein the piston position variable setting means comprises a solenoid for urging the piston toward one side and a return spring for urging the piston toward the other side. Variable valve device.