JPH0634102U - Valve drive for internal combustion engine - Google Patents

Abstract

(57) [Summary] [Purpose] The rear end of the engine valve, which is spring-biased in the valve closing direction, is slidably fitted in the cylinder hole of the fixed cylinder body and the rear surface faces the working hydraulic chamber. A valve drive piston is interlocked and connected, and is set in the middle of the cylinder hole between the working hydraulic chamber and an oil passage communicating with a hydraulic pressure generating unit that generates hydraulic pressure corresponding to the opening timing of an engine valve. A hydraulic oil return amount limiting mechanism that limits the return amount of hydraulic oil in response to the rear end of the valve drive piston passing through the hydraulic buffering start position in the valve closing direction, and the operation from the hydraulic pressure generating means to the operating hydraulic chamber. In a valve train of an internal combustion engine, which is provided with a check valve that allows only oil flow, a delay in closing the engine valve due to an increase in viscosity of hydraulic oil is prevented. The device of the present invention is provided with a spring load changing means 65 ₁ capable of changing the spring load for urging the engine valve V in the valve closing direction so as to increase the spring load at a low temperature.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 According to the present invention, a valve drive piston, which is slidably fitted in a cylinder hole of a fixed cylinder body and has a rear surface facing the working hydraulic chamber, is fitted to a rear end of an engine valve which is spring-biased in a valve closing direction. Between the working hydraulic chamber and the oil passage leading to the hydraulic pressure generating means for generating hydraulic pressure in response to the opening timing of the engine valve, the hydraulic buffer set in the middle of the cylinder hole A hydraulic oil return amount limiting mechanism that limits the return amount of hydraulic oil in response to the rear end of the valve drive piston passing through the start position in the valve closing direction, and the flow of hydraulic oil from the hydraulic pressure generating means to the operating hydraulic chamber. The present invention relates to a valve operating device for an internal combustion engine, which is provided with a check valve that allows only the above.

[0002]

[Prior art]

 Conventionally, such a device is known from, for example, Japanese Patent Laid-Open No. 3-9009.

[0003]

[Problems to be solved by the device]

 By the way, in such a device, when the intake valve or the exhaust valve as the engine valve is closed, the flow rate of the hydraulic oil returning from the hydraulic pressure chamber to the hydraulic pressure generating means is limited by the hydraulic oil return amount limiting mechanism. It slows the closing speed of the intake valve or exhaust valve to mitigate the impact when seated to prevent damage to the intake valve or exhaust valve.However, if the viscosity of the hydraulic oil increases at low temperatures, the hydraulic oil There is a risk that the valve closing seating of the engine valve may be delayed due to an increase in hydraulic oil flow resistance in the return amount limiting mechanism.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a valve operating device for an internal combustion engine, which prevents a delay in closing the engine valve due to an increase in viscosity of hydraulic oil. To do.

[0005]

In order to achieve the above object, a device according to a first aspect of the present invention is a spring capable of changing a spring load for urging an engine valve in a valve closing direction to a side that increases at a low temperature. Equipped with load changing means.

According to a second aspect of the invention, in addition to the structure of the first aspect of the invention, a hydraulic release valve capable of releasing the hydraulic pressure of the oil passage when the valve is opened is connected to the oil passage. It

[0007]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings.

1 to 3 show a first embodiment of the present invention. FIG. 1 is a vertical side view of a valve operating device, FIG. 2 is an enlarged view of a main part of FIG. 1, and FIG. 3 is a valve drive. It is an enlarged perspective view of a piston.

First, in FIG. 1, the cylinder head 11 is provided with an intake valve port 23 opening at the top of a combustion chamber 22 formed between the cylinder head 11 and a cylinder block (not shown) through an intake port 24. An intake valve V 1 serving as an engine valve capable of opening and closing the intake valve port 23 is arranged so as to be vertically movable.

An upper retainer 25 is fixed to the upper end of the intake valve V, and a valve spring 26 is contracted between the upper retainer 25 and a lower retainer 29 that can move up and down relative to the intake valve V. The spring force of the spring 26 urges the intake valve V upward, that is, in the valve closing direction.

A valve operating device 30 for driving the intake valve V to open and close is provided with a driving means 31 for hydraulically driving the intake valve V, and a valve operating cam rotatably arranged above the cylinder head 11. A hydraulic pressure generating means 32 for supplying the hydraulic pressure generated by the cam 28 of the shaft 27 corresponding to the opening timing of the intake valve V to the driving means 31, and a hydraulic circuit 33 connected to the hydraulic pressure generating means 32. Are provided on a support block 34 fixed to the cylinder head 11. Thus, the drive means 31 is provided between the first cylinder body 35 fixed to the support block 34 coaxially with the intake valve V and the first cylinder body 35 while contacting the rear end of the intake valve V. And a valve drive piston 37 that is slidably fitted to the lower portion of the first cylinder body 35 to define an operating hydraulic chamber 36, and the hydraulic pressure generating means 32 is mounted on the support block 34 above the cam 28. Between the fixed second cylinder body 38, the lifter 39 slidably fitted to the support block 34 while slidingly contacting the cam 28, and the upper end of the lifter 39 abutting and the second cylinder body 38 And a cam driven piston 40 slidably fitted to the lower portion of the second cylinder body 38 defining a hydraulic pressure generation chamber 41.

In FIG. 2, a mounting hole 51 coaxial with the intake valve V and a screw hole 52 having a diameter smaller than the mounting hole 51 are coaxially formed in the support block 34 so as to form a step. The first cylinder body 35 is formed by coaxially and integrally connecting a cylindrical portion 35a fitted into the mounting hole 51 and a screw shaft portion 35b screwed into the screw hole 52. A lock nut 54 is screwed into a portion of the shaft portion 35b protruding upward from the screw hole 52. At the upper end of the screw shaft portion 35b, the first cylinder body 35 is rotated to determine its position with respect to the support block 34, and the rotation of the first cylinder body 35 is prevented when the lock nut 54 is rotated. A locking hole 55 such as a hexagonal hole for engaging a tool for cutting is provided.

A cylinder portion 35 a of the first cylinder body 35 is coaxially provided with a bottomed cylinder hole 53 opened to the intake valve V side, and the valve drive piston 37 is provided with a closed end of the cylinder hole 53. A working hydraulic chamber 36 is formed between the cylinder and the cylinder and is slidably fitted in the cylinder hole 53. Further, the support block 34 is provided with an oil passage 49 communicating with the oil pressure generating chamber 41 of the oil pressure generating means 32, and the inner surface of the cylinder hole 53 is provided with an annular recess 44 which is in constant communication with the oil passage 49. The annular recess 44 is provided so that the oil passage 49, that is, the hydraulic pressure generation chamber 41 communicates with the working hydraulic chamber 36 when the intake valve V, that is, the valve drive piston 37 is actuated in a valve opening direction from its fully closed position by a predetermined amount. It is formed.

Between the oil passage 49 and the working hydraulic chamber 36, there is a check valve 42 that allows only the working oil to flow from the hydraulic pressure generating chamber 41 to the working hydraulic chamber 36, and a hydraulic buffer set in the middle of the cylinder hole 53. An operating oil return amount limiting mechanism 43 for limiting the returning amount of operating oil to the hydraulic pressure generating chamber 41 in response to the rear end of the valve drive piston 37 passing through the starting position P in the valve closing direction is interposed. .

The check valve 42 includes a valve hole 56 that is formed in the valve drive piston 37 so as to face the working hydraulic chamber 36, and a spherical valve body that is opened and closed in the working hydraulic chamber 36 and is stored in the working hydraulic chamber 36. 57 and a cage 58 fixed to the valve drive piston 37 to hold the valve body 57 in a free state. Thus, on the outer surface of the valve drive piston 37, there is an annular recess 44 between the valve closed position (the position shown in FIGS. 1 and 2) and the position moved from the valve closed position in the valve opening direction by a predetermined amount. That is, an annular groove 59 communicating with the oil pressure generating chamber 41 is provided, and the valve hole 56 communicates with the annular groove 59.

Referring also to FIG. 3, the hydraulic oil return amount limiting mechanism 43 is provided in the valve drive piston 37 such that the annular recess 44 and the annular recess 44 and the operating hydraulic chamber 36 are always in communication with each other. The orifice 60 and the rear or upper end of the valve drive piston 37 pass through the upper edge of the annular recess 44, which is set as the hydraulic pressure relaxation start position P, in the valve closing direction until just before the intake valve V is seated. The chamber 36 communicates with the annular recess 44 and is formed with a notch 61 provided at the upper end of the valve drive piston 37 so that the flow area of the chamber 36 is gradually narrowed at the upper edge of the annular recess 44.

In the drive means 31 and the hydraulic pressure generating means 32 as described above, the intake valve V is in the fully closed state when the hydraulic pressure in the hydraulic pressure generating chamber 41 is not released and is in the state shown in FIG. When the cam driven piston 40 is pushed upward in response to the rotation, the hydraulic pressure generated in the hydraulic pressure generating chamber 41 is guided to the operating hydraulic chamber 36 via the check valve 42 and the fixed orifice 60, and the operating hydraulic chamber 36 The valve drive piston 37 is pushed down by the hydraulic pressure. During the sliding of the valve drive piston 37 downward, the hydraulic pressure generation chamber 41 communicates directly with the working hydraulic pressure chamber 36 via the annular recess 44, which causes a large amount of oil to flow into the working hydraulic pressure chamber 36. Then, the valve drive piston 37 is pushed further downward, and the intake valve V opens against the spring force of the valve spring 26.

When the pressing force of the cam 28 is released after the intake valve V is fully opened, the intake valve V is driven upward by the spring force of the valve spring 26, that is, in the valve closing direction. The valve drive piston 37 is also pushed upward by the closing operation of the suction valve V, and the oil in the operating hydraulic chamber 36 is returned to the hydraulic pressure generating chamber 41. Thus, during the valve closing operation of the intake valve V, the direct communication state between the annular recess 44 and the operating hydraulic chamber 36 is released, and the operating oil return amount limiting mechanism 43 is provided between the operating hydraulic chamber 36 and the annular recess 44. When intervening, the amount of oil returned from the hydraulic pressure chamber 36 to the annular recess 44, that is, the hydraulic pressure generation chamber 41 is limited. Therefore, the upward moving speed of the intake valve V, that is, the valve closing speed is relaxed during the closing operation, and the intake valve V is gently seated, so that the impact at the time of seating is mitigated.

Further, the support block 34 is provided with a lift sensor S that detects the upper end of the intake valve V when the intake valve V is completely closed.

When the hydraulic pressure in the hydraulic pressure generating chamber 41 of the hydraulic pressure generating means 32 is released during the valve opening operation of the intake valve V, the operating hydraulic pressure chamber 36 overcomes the spring force of the valve spring 26 to open the intake valve V. Insufficient hydraulic pressure cannot be ensured and the cam 28 continues to push the lifter 39 upward, but the intake valve V starts closing operation due to the elastic force of the valve spring 26 from the time when the hydraulic pressure is released. The volume of the generation chamber 41 is reduced.

Referring again to FIG. 1, the hydraulic circuit 33 is responsible for releasing the hydraulic pressure from the hydraulic pressure generating chamber 41 and supplying the hydraulic oil to the hydraulic pressure generating chamber 41, and includes a hydraulic pressure release valve 45 and an accumulator 46. And a one-way valve 47 and a check valve 48, which are disposed on the support block 34.

The hydraulic pressure release valve 45 is provided between an oil passage 49 communicating with the hydraulic pressure generating chamber 41 and formed in the support block 34, and an oil passage 50 communicating with the accumulator 46 and formed in the support block 34. Is a solenoid valve installed in the oil passage 49 and is capable of releasing the oil pressure in the oil passage 49, that is, the oil pressure generating chamber 41 when the valve is opened. The one-way valve 47 is arranged between the oil passage 50 and the oil passage 49 in the support block 34, bypassing the oil pressure release valve 45, and the oil pressure of the oil passage 50 is higher than that of the oil passage 49. Also opens the valve when the pressure exceeds the set pressure and allows only the oil to flow from the accumulator 46 to the oil passage 49, that is, to the hydraulic pressure generation chamber 41. The check valve 48 is provided between the oil passage 50 and an intermediate portion between the accumulator 46 and the one-way valve 47, and the oil passage 19, and allows only the flow of the hydraulic oil from the oil passage 19 to the oil passage 50 side. To do. A pump 15 for pumping hydraulic oil from the oil tank 14 is connected to the oil tank 14 via a relief valve 20 and is connected to an oil supply passage 19 via a filter 17 and a pressure regulating valve 18.

By the way, when the hydraulic pressure release valve 45 releases the hydraulic pressure in the hydraulic chamber 41 during the valve opening operation of the intake valve V, the hydraulic pressure of the accumulator 46 passes through the one-way valve 47 before the next valve opening operation starts. It is returned to the hydraulic pressure generation chamber 41, and the shortage is replenished to the hydraulic pressure generation chamber 41 via the check valve 48. The oil pressure acting on the oil passage 50 via the check valve 48 is between the lower limit pressure, which is the valve opening pressure of the one-way valve 47, and the upper limit pressure, which is the pressure accumulation starting pressure of the accumulator 46. Is required, and the hydraulic pressure is regulated by the pressure regulating valve 18 so as to fall within such a range.

According to the present invention, the valve operating device 30 includes spring load changing means 65 ₁ . The spring load changing means 65 ₁ is slidably fitted in a bottomed sliding hole 66 provided in the cylinder head 11 and forms a hydraulic chamber 68 between itself and the closed end of the sliding hole 66. A piston 67 and a pressure regulator 69 connected to the hydraulic chamber 68 are provided.

At the upper part of the cylinder head 11, a bottomed sliding hole 66 that opens upward is provided in a ring shape surrounding the intake valve V, and a ring-shaped piston 67 that supports the lower retainer 29 is a sliding hole. 66 is slidably and oil-tightly fitted. The hydraulic chamber 68 is connected between the filter 17 and the pressure regulating valve 18 via an oil supply passage 70 in which a pressure regulator 69 is provided.

The pressure regulator 68 is capable of adjusting the hydraulic pressure supplied to the hydraulic chamber 68 according to the temperature, and the hydraulic pressure supplied to the hydraulic chamber 68 is increased when the temperature is low.

Next, the operation of the first embodiment will be described. When the hydraulic pressure is released by the hydraulic pressure release valve 45 during the opening operation of the intake valve V, the suction valve V is released according to the hydraulic pressure release in the operating hydraulic chamber 36. And the lift amount of the intake valve V is reduced. Immediately before the intake valve V is seated by the early closing, the hydraulic oil return amount limiting mechanism 43 works to restrict the hydraulic pressure discharge from the hydraulic pressure chamber 36, so that the closing speed of the intake valve V is relaxed. This prevents the intake valve V from bouncing.

By the way, when the hydraulic oil flow resistance in the hydraulic oil return amount limiting mechanism 43 increases due to an increase in the viscosity of the hydraulic oil at low temperatures, the hydraulic pressure discharge from the hydraulic pressure chamber 36 is further reduced. A delay in closing the intake valve V occurs. However, in the spring load change unit 65 _1, the spacing between the upper retainer 25 and lower portion retainer 29 in accordance with the hydraulic pressure in the hydraulic chamber 68, i.e., to change the set length of the valve spring 26 cut with a low temperature By setting the hydraulic pressure in the hydraulic chamber 68 to a high value by the pressure regulator 69, it is possible to reduce the set length of the valve spring 26 and increase the load of the valve spring 26. Therefore, even if the hydraulic oil flow resistance in the hydraulic oil return amount limiting mechanism 43 increases due to an increase in the viscosity of the hydraulic oil, a spring that only overcomes it and drives the valve drive piston 37 and the intake valve V in the valve closing direction. It is possible to obtain a load, and it is possible to prevent a valve closing delay due to an increase in the viscosity of hydraulic fluid.

Further, during normal operation, the hydraulic pressure in the hydraulic chamber 68 is reduced by the pressure regulator 69, and the spring load of the valve spring 26 can be changed to a value at which the cam 28 and the cam driven piston 39 do not separate. As a result, the frictional force can be reduced and the durability of the cam 28 and the cam driven piston 39 can be improved.

FIG. 4 shows a second embodiment of the present invention, in which parts corresponding to those of the first embodiment are designated by the same reference numerals.

The spring load changing means 65 ₂ is fitted in a bottomed sliding hole 72 provided in the cylinder head 11 so as to be airtight and slidable, and is fixedly connected to the upper end portion of the intake valve V. Connected between a check valve 75 and an air compressor 76 connected to a pneumatic chamber 74 formed between the closed end of the piston 73 and the sliding hole 72 via a check valve 75. And a pressure regulator 77 that is operated.

The sliding hole 72 is provided above the cylinder head 11 coaxially with the intake valve V. The piston 73 is formed in a cylindrical shape with a bottom, and the upper end portion of the intake valve V penetrating the upper end closed portion of the piston 73 is fixedly connected to the piston 73 by a split cotter 78.

The pressure regulator 77 is capable of adjusting the air pressure of the air pressure chamber 74 in accordance with the temperature, and the air pressure of the air pressure chamber 74 is increased when the temperature is low.

Further, the valve spring 26 that is contracted between the upper end closing portion of the piston 73 and the cylinder head 11 is housed in the pneumatic chamber 74, and the load of the valve spring 26 is set to be relatively weak. .

According to the second embodiment, the intake valve V is biased in the valve closing direction by the relatively low spring load of the valve spring 26 and the air spring of the air pressure acting on the piston 73. When the temperature is low, the load of the air spring is increased, so that the spring load acting on the intake valve V in the valve closing direction is increased.

According to the second embodiment, the same effect as that of the first embodiment can be obtained.

As another embodiment of the present invention, a shape memory alloy leaf spring whose spring load is large at low temperature is interposed between the lower retainer 29 and the cylinder head 11 in FIG. Alternatively, the valve spring 26 itself may be formed of a shape memory alloy so that the spring load increases at low temperatures.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the present invention described in the scope of claims for utility model registration. It is possible to make design changes.

For example, the present invention can be implemented in connection with an exhaust valve as an engine valve.

[0040]

[Effect of device]

 As described above, the device according to the first aspect of the present invention is provided with the spring load changing means that can change the spring load for urging the engine valve in the valve closing direction to the side that increases when the temperature is low. The engine valve can be driven in the valve closing direction against an increase in hydraulic oil flow resistance in the mechanism, and a delay in closing the engine valve can be prevented.

According to the second aspect of the invention, in addition to the configuration of the second aspect of the invention, a hydraulic release valve capable of releasing the hydraulic pressure of the oil passage when the valve is opened is connected to the oil passage. Therefore, when the hydraulic pressure release valve is closed early by opening the valve, it is possible to prevent the engine valve from bouncing by the hydraulic oil return amount limiting mechanism, and at that time, it is possible to prevent a delay in opening the valve at low temperatures. .

[Brief description of drawings]

FIG. 1 is a vertical sectional side view of a valve train according to a first embodiment of the present invention.

FIG. 2 is an enlarged view of a main part of FIG.

FIG. 3 is an enlarged perspective view of a valve drive piston.

FIG. 4 is an enlarged sectional view of a main part of a second embodiment of the present invention.

[Explanation of symbols]

30 Valve Operating Device 32 Hydraulic Pressure Generating Means 35 Cylinder Body 36 Working Hydraulic Chamber 37 Valve Drive Piston 42 Check Valve 43 Hydraulic Oil Return Amount Limiting Mechanism 45 Hydraulic Release Valve 49 Oil Path 53 Cylinder Hole 65 ₁ , 65 ₂ Spring Load Changing Means P Hydraulic Pressure Buffer start position V Intake valve as engine valve

Claims (2)

[Scope of utility model registration request] 1. An engine valve (V) which is spring-biased in a valve closing direction.
At the rear end of the cylinder body (35) of the fixed cylinder hole (5
3) The valve drive piston (37), which is slidably fitted in the hydraulic pressure chamber (36) and is slidably fitted to the rear surface, is interlocked and coupled, and the hydraulic pressure is adjusted according to the opening timing of the engine valve (V). Between the oil passage (49) communicating with the oil pressure generating means (32) for generating the pressure and the working oil pressure chamber (36).
3) A hydraulic oil return amount limiting mechanism for limiting the return amount of hydraulic oil in response to the rear end of the valve drive piston (37) passing in the valve closing direction at the hydraulic buffer start position (P) set in the middle of (43) and a check valve (42) which allows only the flow of hydraulic oil from the hydraulic pressure generating means (32) to the hydraulic pressure chamber (36),
Spring load changing means (65 ₁ , 6) capable of changing the spring load for urging the engine valve (V) in the valve closing direction to the side that increases at low temperature.
5 ₂ ) A valve train for an internal combustion engine, comprising: 2. The internal combustion engine according to claim 1, wherein a hydraulic pressure release valve (45) capable of releasing the hydraulic pressure of the oil passage (49) when the valve is opened is connected to the oil passage (49). Engine valve system.