JPH04292506A - Hydraulic drive device for engine valve for internal combustion engine - Google Patents

Abstract

PURPOSE:To improve the functional response of a valve and to reduce its working sound by connecting a detector to detect an index representing the viscosity of a working oil to a control means, and changing the control means in stages or continuously. CONSTITUTION:A valve driving piston 13 which faces a hydraulic chamber 17 formed between a cylinder body 16 and itself on its back and moreover abuts on the rear end of an engine valve V at its front end is slidably fitted in the cylinder body 16 fixed to a stationary supporting section 12. A hydraulic pressure generating means 8 to generate oil pressure correspondingly to the valve opening term of the engine valve V and an electromagnetic opening and closing valve 15 to release the oil pressure in the hydraulic chamber 17 at the time of opening the valve 15 are connected to the hydraulic chamber 17. A detector 70 to detect an index representing the viscosity of a working oil is connected to a control means C, which is formed to change a driving electric power for the valve 15 in stages or continuously so as to increase it when the viscosity of the working oil is high.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention provides a cylinder body that is fixed to a fixed support part, the back side of which faces a hydraulic chamber formed between the cylinder body, and the front end of which is brought into contact with the rear end of an engine valve. A valve drive piston is slidably fitted in the hydraulic chamber, and the hydraulic chamber includes a hydraulic pressure generating means for generating hydraulic pressure corresponding to the opening timing of the engine valve, and a hydraulic pressure generating means for releasing the hydraulic pressure in the operating hydraulic chamber when the valve is opened. An engine valve for an internal combustion engine, in which a control means for controlling the opening/closing operation of the electromagnetic opening/closing valve is connected to the electromagnetic opening/closing valve in order to change the opening/closing operation characteristics of the engine valve in accordance with the requests of the engine. The present invention relates to a hydraulic drive device.

0002

[Prior Art] Conventionally, such a device has been used, for example, in Japanese Patent Application Laid-open No. 6
It is publicly known from Publication No. 1-275516 and the like.

0003

[Problems to be Solved by the Invention] By the way, the viscosity of hydraulic oil increases as its temperature decreases, and in the operating part of an electromagnetic on-off valve, as the viscosity increases, the resistance of the hydraulic oil increases. As the viscosity increases and the viscosity decreases, the resistance of the hydraulic fluid decreases. However, in the above conventional system, the electric power that drives the electromagnetic on-off valve is constant regardless of the viscosity of the hydraulic oil, that is, the temperature. Therefore, when the viscosity of the hydraulic oil is high, the response of the electromagnetic on-off valve decreases, and the viscosity of the hydraulic oil decreases. When it is low, the responsiveness of the electromagnetic on-off valve increases significantly and an operating noise is generated due to collision of the operating parts.

The present invention has been made in view of the above circumstances, and is designed to adapt the operating characteristics of an electromagnetic on-off valve to the viscosity of the hydraulic oil, thereby improving the operational response when the hydraulic oil is highly viscous and improving the operational response when the hydraulic oil is low in viscosity. An object of the present invention is to provide a hydraulic drive device for an engine valve for an internal combustion engine, which is designed to reduce operating noise.

[0005]

[Means for Solving the Problems] In order to achieve the above object, according to the present invention, a detector for detecting an index representative of the viscosity of hydraulic oil is connected to a control means, and the control means is configured to control electromagnetic switching. The valve driving power is configured to be changed stepwise or continuously so that the driving power of the valve is increased when the viscosity of the hydraulic oil is high.

[0006]

Embodiments Hereinafter, embodiments of the present invention will be explained with reference to the drawings.

1 to 7 show an embodiment of the present invention, in which FIG. 1 is a vertical sectional view of a hydraulic drive device, FIG. 2 is an enlarged vertical sectional view of an electromagnetic on-off valve, and FIG. 3 is a diagram showing the viscosity of hydraulic oil. Fig. 4 is a comparison diagram with the conventional electromagnetic attraction force depending on the high and low viscosity of the hydraulic oil. Fig. 5 is a diagram showing the duty ratio determined depending on the high and low viscosity of the hydraulic oil. Fig. 6 is a graph showing changes in actuation response depending on high and low hydraulic oil viscosity, and Fig. 7 is a graph showing changes in operational response according to high and low hydraulic oil viscosity.
FIG. 3 is a comparison diagram of the operating sound level according to the low level and the conventional level.

First, in FIG. 1, intake valves V as engine valves are disposed in a cylinder head HC of an internal combustion engine so as to be able to open and close while being biased in the valve closing direction by a valve spring 11. A hydraulic drive device U for opening and closing V is disposed in the cylinder head HC.

[0009] The hydraulic drive device U has a cylinder head HC.
A support block 12 serving as a support unit coupled to the intake valve V is driven by a valve drive piston 13 that is interlocked and connected to the intake valve V, and a cam 22 provided on the camshaft S to correspond to the opening timing of the intake valve V. A hydraulic pressure generating means 8 capable of generating hydraulic pressure according to the request of the engine, and an electromagnetic opening/closing valve 15 capable of releasing the hydraulic pressure generated by the hydraulic pressure generating means 8 in order to change the opening/closing operation characteristics of the intake valve V according to the request of the engine are provided. It is what it is.

A first cylinder body 16 is fixed to the support block 12 coaxially with the intake valve V, and a valve driving piston 13 that abuts the upper end of the intake valve V slides on the first cylinder body 16. A hydraulic chamber 17 is formed between the valve drive piston 13 and the cylinder body 16 so that the back surface of the valve drive piston 13 is exposed.

The hydraulic pressure generating means 8 includes a second cylinder body 18 fixed to the support block 12 above the cam 22, and a second cylinder body 18 that is in sliding contact with the cam 22 and is slidable on the support block 12 coaxially with the second cylinder body 18. A hydraulic pressure generation chamber 20 is defined between a bottomed cylindrical lifter 19 that is fitted into the lifter 19 and the second cylinder body 18 with its lower end abutting the lifter 19, and the lifter 19 is slid onto the second cylinder body 18. It includes a cam driven piston 14 that is freely fitted.

The hydraulic pressure chamber 17 and the hydraulic pressure generation chamber 20 communicate with each other when the intake valve V, that is, the valve driving piston 13, moves in the valve opening direction by a predetermined amount from its fully closed position. A check valve 21 is provided that only allows flow of hydraulic oil from the oil pressure generation chamber 20 to the oil pressure chamber 17, and a throttle mechanism is provided between the oil pressure chamber 17 and the oil pressure generation chamber 20.

By the way, the hydraulic pressure generation chamber 20 and the hydraulic pressure chamber 1
7, the intake valve V is in communication between the state where it has been lifted by a predetermined amount from the fully closed position and the state where it is fully open, and the hydraulic pressure generating chamber 20 is in communication until the intake valve V is lifted by a predetermined amount from the fully closed position. The hydraulic fluid is communicated through a check valve 21 that only allows flow of hydraulic fluid from the hydraulic chamber 17 to the hydraulic chamber 17, and a throttle mechanism that limits the amount of hydraulic fluid that returns from the hydraulic chamber 17 to the hydraulic pressure generation chamber 20. When the intake valve V is fully closed, the hydraulic drive device U is in the state shown in FIG. 1, and from this state shown in FIG. 1, the lifter 19 is pushed up by the cam 22 in accordance with the rotation of the camshaft S. As a result, the cam driven piston 1
4 is pushed upward, the volume of the oil pressure generation chamber 20 is contracted, and the hydraulic oil in the oil pressure generation chamber 20 is transferred to the check valve 2.
1 and a throttle mechanism into the hydraulic chamber 17. Therefore, the hydraulic pressure in the hydraulic chamber 17 becomes large, and the valve drive piston 1
3 is pushed down, and the intake valve V is driven to open against the spring force of the valve spring 11. Further, after the intake valve V is fully opened, when the pressing force on the lifter 19 by the cam 22 is released, the intake valve V is driven upward by the spring force of the valve spring 11, that is, in the valve closing direction. Due to this valve closing operation of the intake valve V, the valve driving piston 13 is also pushed upward, and the hydraulic oil in the hydraulic chamber 17 is returned to the hydraulic pressure generation chamber 20. Since the check valve 21 and throttle mechanism have been interposed in between,
The amount of hydraulic fluid that returns from the hydraulic chamber 17 to the hydraulic pressure generation chamber 20 is limited, and the upward movement speed of the intake valve V, that is, the valve closing speed, is slowed in the middle of the valve closing operation, so that the impact when seating is alleviated. become.

A lift sensor 23 is also disposed on the support block 12 to detect the upper end of the intake valve V when the intake valve V is completely closed.

When the hydraulic pressure in the hydraulic chamber 17 and the hydraulic pressure generation chamber 20 is released during the opening operation of the intake valve V, the hydraulic pressure in the hydraulic chamber 1
7 loses its transmission function to overcome the spring force of the valve spring 11 and keep the intake valve V open, and even though the cam 22 continues to push the lifter 19 upward, the intake valve V does not open as described above. When the hydraulic pressure is released, the valve starts to close due to the elastic force of the valve spring 11, and the volume of the hydraulic chamber 17 is reduced.

The electromagnetic on-off valve 15 is an electromagnetic valve that controls the release timing of the hydraulic pressure from the above-mentioned hydraulic chamber 17 and the hydraulic pressure generation chamber 20, that is, the lift amount and closing timing of the intake valve V.
A passageway 1 is interposed between a passageway 1 bored through the support block 12 and communicating with the hydraulic pressure generation chamber 20, and a passageway 2 bored through the support block 12 while communicating with an accumulator 24 disposed in the support block 12. Ru. Further, a one-way valve 25 is disposed in a detour 7 provided in the support block 12 by bypassing the electromagnetic on-off valve 15 between the two passages 1 and 2, and this one-way valve 25 is connected to the second passage. When the oil pressure in the first passage 1 becomes greater than the oil pressure in the first passage 1 by a set pressure or more, the valve opens and only allows the flow of hydraulic oil from the accumulator 24 toward the passage 1, that is, the oil pressure generation chamber 20. Further, an oil pump 4 that pumps up hydraulic oil from an oil bath 3 provided in the cylinder head HC is connected to an oil passage 6 provided with a filter 5. It is connected to the passage 2 via a stop valve 26. The check valve 26 only allows the hydraulic oil to flow from the oil pump 4 toward the passage 2 side.

In FIG. 2, the support block 12 is provided with a mounting hole 27 opening on the outer surface of its upper part for mounting the electromagnetic on-off valve 15 therein. This mounting hole 27 has, in order from the inside along the axial direction, a small diameter hole 28, a large diameter hole 29 larger than the small diameter hole 28, and a screw thread larger in diameter than the large diameter hole 29. The passage 1 is coaxially connected to the small diameter hole 28. In the small diameter hole 28,
The filter 40 is fitted flush with the step surface between the small diameter hole 28 and the large diameter hole 29. Further, the passage 2 is opened on the side surface of the large diameter hole 29 closer to the small diameter hole 28 .

On the other hand, the housing 31 of the electromagnetic on-off valve 15 includes a valve housing portion 33 provided at the front end of a housing main body 32, and a fixed core 34 attached to the rear end of the housing main body 32. The housing main body 32 includes an outer cylinder part 35 having a smaller diameter than the screw hole part 30, an inner cylinder part 36 disposed coaxially within the outer cylinder part 35, and an outer cylinder part 35.
and a connecting plate portion 37 that connects one end of the inner cylindrical portion 36, and a collar portion that has an outer diameter slightly smaller than the inner diameter of the screw hole portion 30 and extends radially outward from one end of the outer cylindrical portion 35. 38
and a connecting cylinder part 39 that has an outer diameter that fits into the large diameter hole 29 and is coaxially connected to the connecting plate part 37 while extending on the opposite side from the outer cylinder part 35 and the inner cylinder part 36. . Moreover, the axial length of the inner cylinder part 36 from the connecting plate part 37 is set smaller than the axial length of the outer cylinder part 35 from the connecting plate part 37.

The valve housing portion 33 includes an outer guide cylinder 41 and an inner guide cylinder 42 disposed coaxially within the outer guide cylinder 41.
With the outer guide cylinder 41 and the inner guide cylinder 42 fitted into the connecting cylinder part 39 with the inner guide cylinder 42 in contact with the connecting plate part 37, the tip of the connecting cylinder part 39 is removed. The valve housing part 33 is configured by being caulked to the guide cylinder 41, and the valve housing part 33
is connected to the front end of the housing main body 33. Further, the fixed core 34 is caulked to the rear end of the outer cylindrical portion 35.

Housing 3 of such electromagnetic on-off valve 15
1, the connecting cylinder portion 39 of the housing main body 32 is inserted into the large diameter hole 2 until the valve housing portion 33 is brought into contact with the filter 40.
9 and is inserted into the mounting hole 27. Further, a cylindrical collar 44 is screwed into the screw hole 30 of the mounting hole 27, and by tightening the collar 44 until its tip abuts against the flange 38 of the housing 31, the electromagnetic on-off valve 15 The housing 31 is sandwiched and fixed between the collar 44 and the support block 12.

Outer guide cylinder 4 in valve housing part 33
An inlet port 47 coaxially communicating with the passage 1 via a filter 40 is provided at one end of the outer guide cylinder 41, and a plurality of outlet ports 48 are provided at intervals in the circumferential direction on the side wall of the outer guide tube 41 near the inlet port 47. drilled. Moreover, the support block 12
An annular passage 49 communicating with each outlet port 48 and the passage 2 is formed between the inner surface of the large diameter hole 29 in the mounting hole 27 and the outer guide cylinder 41, and the connecting cylinder part 3 of the housing main body 32
An annular seal member 50 for sealing between the annular passage 49 and the outside is fitted onto the outer surface of the annular passage 9 .

A main valve body 51 formed in the shape of a cylinder with a bottom is fitted into the valve housing portion 33 so that its outer surface is in sliding contact with the inner surface of the outer guide cylinder 41. 5
1 is located at a position where it seats on a tapered valve seat 52 provided on the outer guide tube 41 so as to surround the inner edge of the inlet port 47 and blocks the connection between the inlet port 47 and the outlet port 48; and at a position where it is separated from the valve seat 52. and a position communicating between the inlet port 47 and the outlet port 48.

A back pressure chamber 53 is formed in the valve housing portion 33 so as to face the back side of the main valve body 51.
A spring 54 is housed in the back pressure chamber 53, which exerts a spring force in a direction to seat the main valve body 51 on the valve seat 52. Therefore, on the main valve body 51, the fluid pressure of the inlet port 47 acts in the valve opening direction, the fluid pressure in the back pressure chamber 53 acts in the valve closing direction, and the spring force of the spring 53 acts in the valve closing direction. become. Furthermore, a throttle 55 that communicates between the inlet port 47 and the back pressure chamber 53 is bored in the main valve body 51 at a position offset from the axis.

Inner guide cylinder 4 in valve housing portion 33
2 serves as a stopper by coming into contact with the main valve body 51 when the main valve body 51 is opened.
A pilot valve hole 56 is coaxially formed at the tip of the inner guide cylinder 42 facing the back surface of the inner guide cylinder 42 . In addition, the inner guide tube 42
A pilot valve body 5 in which a pilot valve hole 56 can be closed
7 is slidably fitted, and the pilot valve body 57
is biased in the valve opening direction, that is, in the backward direction, by a spring 58 interposed between the valve housing portion 33 and the valve housing portion 33 . Moreover, the pilot valve body 57 has a pilot valve hole 56 when the valve is opened.
A communication passage 60 communicating with the pilot valve body 57 is coaxially bored, and the communication passage 60 is opened at the rear end of the pilot valve body 57.

A drive rod 61 is disposed within the inner cylindrical portion 36 of the housing main body 32 via a sleeve 59 so as to be movable in the axial direction, and the tip of the drive rod 61 is coaxially connected to the rear end of the pilot valve body 57. be touched. Furthermore, a movable core 62 is disposed between the end of the inner cylindrical portion 36 and the fixed core 34 so as to be movable in the axial direction, and the rear end of the drive rod 61 is coupled to the movable core 62. . Moreover, a spring 63 is compressed between the movable core 62 and the fixed core 34, and the movable core 62 is moved to the inner cylinder part 36 by the spring 63.
Forced to the side. Further, a communication passage 64 and a communication hole 65 communicating with the communication passage 60 are bored in the drive rod 61 and the fixed core 34.

A coil 67 wound around a bobbin 66 is disposed between the outer cylindrical portion 35 and the inner cylindrical portion 36 of the housing main body 32, and a lead wire 6 connected to the coil 67 is provided.
8 is pulled out from the fixed core 34.

In such an electromagnetic on-off valve 15, the coil 6
7, the movable core 62 and the drive rod 61 retreat against the spring force of the spring 63, and the pilot valve body 57 retreats following the drive rod 61, thereby opening the pilot valve hole 47. As a result, the hydraulic pressure in the back pressure chamber 53 is released, the balance of the hydraulic pressure acting on both sides of the main valve body 51 is disrupted, and the valve opening force due to the hydraulic pressure of the inlet port 47 acting on the front surface of the main valve body 51 is transferred to the back pressure chamber 53. Hydraulics and springs 54
The valve opens by overcoming the valve closing force. Also coil 67
In the demagnetized state, the movable core 62 and the drive rod 61 move forward by the spring force of the spring 63, and the pilot valve body 57 moves forward until it closes the pilot valve hole 56. As a result, the hydraulic pressure of the inlet port 47 acts on the back pressure chamber 53 via the throttle 55, and the main valve body 51 is operated to close.

Referring again to FIG. 1, the excitation and demagnetization of the coil 67 of the electromagnetic on-off valve 15 is controlled by a control means C consisting of a computer, and when the valve is opened, the coil 67 is
An intermittent current is applied as excitation power. Moreover, the control means C controls the coil 6 to open the electromagnetic on-off valve 15.
The control means C includes a detector 70 that detects the temperature of the hydraulic oil as an index representative of the viscosity of the hydraulic oil.
is connected. In the control means C, the duty ratio of the intermittent current applied to the coil 67 is set as shown in FIG. 3(a) when the hydraulic oil temperature detected by the detector 70 is high, that is, when the hydraulic oil viscosity is low. On the other hand, when the hydraulic oil temperature detected by the detector 70 is low, that is, when the hydraulic oil viscosity is high, the duty ratio of the intermittent current applied to the coil 67 is set as shown in FIG. 3(b). There is. That is, the duty ratio when the viscosity of the hydraulic oil is high is set larger than the duty ratio when the viscosity is low. In contrast, in the conventional system, the duty ratio is determined regardless of changes in the viscosity of the hydraulic oil, as shown by the chain line.

Next, the operation of this embodiment will be explained. The internal operating parts of the electromagnetic on-off valve 15, that is, the main valve body 51, the pilot valve body 57, and the movable core 62 are filled with hydraulic oil. If the electromagnetic attraction force of the movable core 62 toward the fixed core 34 side generated by the excitation of the coil 67 is constant, the operational response of these operating parts will depend on the viscosity of the surrounding hydraulic oil. However, the control means C excites the coil 67 by increasing the duty ratio when the viscosity of the hydraulic oil is high and decreasing the duty ratio when the viscosity of the hydraulic oil is low. Therefore, as shown in FIG. 4, the electromagnetic attraction force of the movable core 62 toward the fixed core 34 is constant regardless of the viscosity of the hydraulic oil as shown by the white area in the conventional case. As mentioned above, by changing the duty ratio depending on whether the viscosity of the hydraulic oil is high or low, it changes as shown in the shaded area, and when the viscosity of the hydraulic oil is high, the electromagnetic attraction force becomes stronger than that of conventional ones. , When the viscosity of the hydraulic oil is low, the electromagnetic attraction force becomes weaker than that of the conventional one.

When the electromagnetic attraction force is changed in accordance with changes in the viscosity of the hydraulic oil in this way, the operational response of the actuating part of the electromagnetic on-off valve 15 changes as indicated by the diagonal lines in FIG. 5 depending on whether the viscosity of the hydraulic oil is high or low. It becomes as shown in the section. That is, when the viscosity of the hydraulic oil is high, the operational response is improved compared to the conventional type shown by the white area, and when the viscosity of the hydraulic oil is low, the operational response is lower than the conventional type shown by the white area. In this way, the operational response of the electromagnetic on-off valve 15 changes according to changes in the viscosity of the hydraulic fluid, as shown by the broken line in FIG. As shown in , it remains almost constant regardless of changes in hydraulic oil viscosity. This makes it possible to improve the operational response of the electromagnetic on-off valve 15 when the viscosity of the hydraulic oil is high, that is, when the temperature is low. Furthermore, by making the operating response of the electromagnetic on-off valve 15 almost constant regardless of changes in the viscosity of the hydraulic oil, the operating sound level can be kept almost constant regardless of changes in the viscosity of the hydraulic oil, as shown in FIG. . In other words, when the viscosity of the hydraulic oil is high, the operating speed is faster than that of the conventional type, so the operating noise level is slightly increased as shown by the shaded area compared to the conventional type shown in the white area, and the viscosity of the hydraulic oil is also increased. When the operating speed is low, the operating sound level can be significantly lowered as shown by the hatched area compared to the conventional system shown by the white area.

As another embodiment of the present invention, as shown in FIG. 8, the voltage applied to the coil 67 of the electromagnetic on-off valve 15 is
Even if the viscosity of the hydraulic oil is changed stepwise so that the viscosity decreases as the viscosity of the hydraulic oil decreases, the same effect as in the above embodiment can be obtained.

In the embodiments described above, the temperature of the hydraulic oil is detected as an index representative of the viscosity of the hydraulic oil, but the temperature of the engine cooling water may also be detected. The present invention is also applicable to a hydraulic drive device for an exhaust valve.

[0033]

As described above, according to the present invention, a detector for detecting an index representative of the viscosity of hydraulic oil is connected to the control means, and the control means controls the driving power of the electromagnetic on-off valve to the viscosity of the hydraulic oil. Since the viscosity is configured to change stepwise or continuously so as to increase when the viscosity is high, it is possible to improve the operational response when the hydraulic oil is high in viscosity and to reduce the operational noise when the hydraulic oil is low in viscosity. becomes possible.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a hydraulic drive device according to an embodiment of the present invention.

FIG. 2 is an enlarged vertical cross-sectional view of the electromagnetic on-off valve.

FIG. 3 is a diagram showing duty ratios determined according to high and low viscosity of hydraulic oil.

FIG. 4 is a comparison diagram of the electromagnetic attraction force with the conventional one depending on the high and low viscosity of the hydraulic oil.

FIG. 5 is a diagram comparing the operational response according to the high and low viscosity of the hydraulic oil with the conventional one.

FIG. 6 is a graph showing changes in operational response depending on whether the viscosity of the hydraulic oil is high or low.

FIG. 7 is a comparison diagram of the operating sound level according to the high and low viscosity of the hydraulic oil with the conventional one.

FIG. 8 is a graph showing changes in applied voltage according to high and low viscosity of hydraulic oil in another embodiment of the present invention.

[Explanation of symbols]

8 Hydraulic pressure generating means 12
Support block 13 as a support part
Valve drive piston 15
Electromagnetic on-off valve 16 Cylinder body 17 Hydraulic chamber 70 Detector C Control means

Claims (3)

[Claims] Claim 1: A cylinder body (16) fixed to a fixed support part (12) is provided with its rear face facing a hydraulic chamber (17) formed between the cylinder body (16) and its front end facing toward the engine. The valve drive piston (1) is brought into contact with the rear end of the valve (V).
3) is slidably fitted in the hydraulic chamber (17), and
A hydraulic pressure generating means (8) that generates hydraulic pressure in accordance with the opening timing of the engine valve (V) is connected to an electromagnetic on-off valve (15) that can release the hydraulic pressure in the hydraulic chamber (17) when the valve is opened. , a control means (C) for controlling the opening/closing operation of the electromagnetic on-off valve (15) to change the opening/closing operation characteristics of the engine valve (V) in accordance with the request of the engine;
) is connected to an electromagnetic on-off valve (15) in a hydraulic drive system for an engine valve for an internal combustion engine. The control means (C) is configured to stepwise or continuously change the driving power of the electromagnetic on-off valve (15) so as to increase the driving power when the viscosity of the hydraulic oil is high. Hydraulic drive system for engine valves. 2. The control means (C) is configured to change the duty ratio of the intermittent current applied to the electromagnetic on-off valve (15) according to the viscosity of the hydraulic oil. 1. The hydraulic drive device for an engine valve for an internal combustion engine according to 1. 3. The control means (C) includes an electromagnetic on-off valve (
15. The hydraulic drive device for an engine valve for an internal combustion engine according to claim 1, wherein the hydraulic drive device is configured to change the voltage applied to the valve in accordance with the viscosity of the hydraulic oil.