JPH0788817B2 - Hydraulic control device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a hydraulic control device, and is effectively used, for example, for controlling the timing of opening and closing an intake valve of an engine.

[Conventional technology]

Conventionally, a hydraulic control valve for switching control of hydraulic pressure supply using a piezo actuator, or a intake valve using a switching valve driven by a solenoid, as shown in Japanese Utility Model Laid-Open No. 61-140105. There is also one that controls the hydraulic pressure supplied to the cylinder to control the lift amount of the intake valve.

[Problems to be Solved by the Invention] However, in the conventional configuration as described above, for example, in a configuration using a switching valve driven by a solenoid, it may not be possible to follow the high speed drive of the intake valve, There was a problem that it was not possible to perform delicate control. Further, conventionally, there has been no one that controls the hydraulic pressure in multiple stages and at high speed so that control such as adjusting the lift amount of the intake valve to enhance the swirl effect and reducing pumping loss can be performed. The present invention has been found in view of the above points, and an object of the present invention is to provide a hydraulic control device that realizes hydraulic control with high speed followability and that can set and control pressure in multiple stages.

[Means for Solving the Problems] In order to achieve the above object, in the hydraulic control device of the present invention, a variable pressure chamber and a hydraulic chamber for temporarily holding a fluid are formed, and the hydraulic pump is intermittently pumped. A housing provided with a relief port for relieving the fluid in the hydraulic chamber to the outside, and a housing provided with a passage for guiding the incoming fluid to the variable pressure chamber and the hydraulic chamber, and housed in the housing. Along with that, the variable pressure chamber is partitioned and formed, and a piezo actuator that expands and contracts according to the applied voltage to expand and reduce the volume of the variable pressure chamber, and the pressure inside the variable pressure chamber and the hydraulic chamber that are reciprocally provided in the housing. A needle valve that receives and connects or shuts off the hydraulic chamber and the relief port, and a valve provided in the middle of the passage from the hydraulic pump to the variable pressure chamber A first check valve that allows the movement of fluid and prevents the movement of the fluid from the variable pressure chamber to the hydraulic pump side; and a movement of the fluid from the hydraulic pump to the hydraulic chamber that allows the fluid to move from the hydraulic chamber to the hydraulic pump side. A second check valve to prevent the transfer of fluid to the
And a control means for controlling the drive of the piezo actuator, wherein the fluid pumped from the hydraulic pump is pumped to each of the variable pressure chamber and the hydraulic chamber through the passage and the first and second check valves. When the fluid pressure in the hydraulic chamber is higher than the fluid pressure in the variable pressure chamber, the needle valve shuts off the hydraulic chamber and the relief port, applies a voltage to the piezo actuator, and changes the fluid pressure in the variable pressure chamber. Is higher than the fluid pressure in the hydraulic chamber, the needle valve communicates the hydraulic chamber with the relief port, and the needle valve has a passage communicating the variable pressure chamber with the hydraulic chamber, and the passage in the middle of the passage. And a third chain that is arranged in the hydraulic pressure chamber and is capable of moving fluid from the hydraulic chamber to the variable pressure chamber, and that prevents movement of fluid from the variable pressure chamber to the hydraulic chamber. Has a click valve, wherein the facing surface of the third check valve of the hydraulic chamber part of the housing with the movement the third needle valve opening the third
The check valve of No. 1 has a technical means that it has a protrusion forcibly opening.

[Operation and Effect] With the above configuration, the pressure oil supplied from the hydraulic pump is supplied to the variable pressure chamber and the hydraulic chamber via the first check valve and the second check valve, and the pressure in the hydraulic chamber is the same as that of the hydraulic pump. Increases pressure as pressure increases. Then, when the pressure feed of the hydraulic pump is stopped by the second check valve, the pressure in the hydraulic chamber is maintained constant. In addition, the volume of the variable pressure chamber expands and contracts according to the drive of the piezo actuator, and the pressure of the variable pressure chamber becomes higher than the pressure of the hydraulic chamber, so the needle valve moves and the hydraulic chamber and the relief port communicate with each other. This reduces the pressure in the hydraulic chamber. At this time, the passage provided in the needle valve, the third check valve, and the projection communicate with the variable pressure chamber and the hydraulic chamber, and the pressure in the variable pressure chamber also decreases. Can be set to. Also, if the piezo actuator is de-energized during the pressure drop of the hydraulic chamber, the communication between the hydraulic chamber and the relief port will be closed again, so it is possible to maintain the pressure different from the pressure supplied from the hydraulic pump. This makes it possible to realize optimal hydraulic control for an intake valve control device that requires particularly high-speed responsiveness and requires multiple lift levels.

〔Example〕

A first embodiment of the present invention will be described below with reference to FIG. Reference numeral 1 denotes a hydraulic pump, which does not have a normal metering mechanism and an oil distribution mechanism, but has a simple structure having only a mechanism capable of intermittently discharging a fixed amount of oil at a predetermined timing.
Reference numeral 11 is a suction return valve for reducing the pressure in the pipe 14 after the oil in the pump chamber 12 is discharged by the plunger 13.

2 is an intake valve drive unit, which is an intake valve
The piston 21 is used to reciprocate 21. That is, it has an accumulator chamber 22 into which oil from the hydraulic pump 1 flows in and out, and the oil pressure in this accumulator chamber 22 drives the piston 23 in the vertical direction in the figure. The intake valve 21 is always urged by the spring 24 in the valve closing direction.

A hydraulic control valve 3 has a piezo actuator 31 and a piezo holder 33 that holds a disc spring 321 that constantly urges the hydraulic piston 32 upward. Also, the control valve housing 37
The needle valve 34, the first check valve 35, and the second check valve 36 are held in the. A variable pressure chamber 38 is formed in the space between the hydraulic piston 32 and the control valve housing 37. In addition, the control valve housing 37 has a needle valve
A hydraulic chamber 39 provided at the lower portion of 34, a hydraulic port 40 for guiding the hydraulic pressure of the hydraulic chamber 39 to the intake valve drive unit 2, a needle valve 34 opened downward again, and oil in the hydraulic chamber 39 is relieved. A relief port 41 is provided to allow this.

The needle valve 34 is biased by a spring 42 in the valve closing direction. An O-ring 43 is attached to the hydraulic piston 32 to keep the variable pressure chamber 38 oil-tight. Needle valve 34
Is slidably housed in the valve housing 37 while keeping airtightness, and a tapered portion 341 is formed in the central portion of the valve 34. The taper portion 341 is configured such that the hydraulic chamber 39 and the relief port 41 can serve as a conducting means. Further, the needle valve 34 has a passage 34 that connects the variable pressure chamber 38 and the hydraulic chamber 39.
2 is configured, and from the hydraulic chamber 39 to the variable pressure chamber in the middle of the passage 342.
A check valve 343 is inserted in such a direction as to allow oil to pass through to the valve 38, but to prevent the oil from flowing from the variable pressure chamber 38 to the hydraulic chamber 39.
A projection 431 is provided on the wall surface of the check valve 343 facing the hydraulic chamber 39. When the needle valve 34 moves downward, the projection 431 forcibly opens the check valve 343 and the hydraulic chamber 39 and the transformer room 38 communicate with each other.

The piezo actuator 31 has a diameter of 15 mm and a thickness of 0.5 mm, for example.
The disk-shaped piezoelectric element and a copper plate having a diameter of 15 mm and a thickness of 0.01 mm are alternately laminated into a cylindrical shape, and a lead wire 311 is provided so that a voltage can be applied in parallel in the thickness direction of each piezoelectric element.
And the copper plate are connected. Lead wire 311 is grommet 3
It extends to the outside of the piezo holder 33 via 12 and is connected to the electric circuit 100. For the piezoelectric element, for example, a ferroelectric ceramic that is fired with lead zirconate titanate as a main component is used. This ferroelectric ceramic is a typical element having a piezo effect. The physical property is 0.5μ when a voltage of 500V is applied in the thickness direction per one of the above.
When the thickness increases by m in the thickness direction and conversely a voltage of 500 V is generated, short-circuiting both ends to discharge the accumulated charge reduces the thickness by 0.5 μm. In addition, a voltage of 200 V is generated in the thickness direction. In this embodiment, the piezo actuator 31 has 100 piezoelectric elements electrically connected in parallel. Therefore, when a voltage of 500 V is applied, a total extension of 50 μm can be obtained. The axial expansion / contraction of the piezo actuator 31 causes the hydraulic piston 32 to move up and down.

The oil discharged from the injection pump 1 via the suction return valve 11 enters the variable pressure chamber 38 via the first check valve 35. Furthermore, the structure is such that it is introduced into the hydraulic chamber 39, the hydraulic port 40, and the accumulator chamber 22 of the intake valve drive unit 2 via the second check valve 36.

Next, the operation of the device having the above configuration will be described.

The injection pump 1 rotates in synchronization with the engine, and the pump chamber
The oil sucked in 12 is discharged into the pipe 14 at a predetermined timing via the suction return valve 11 due to the rise of the plunger 13. The discharged oil flows into the variable pressure chamber 38 via the first check valve 35 of the hydraulic control valve 3 and pushes the hydraulic piston 32 upward in the figure. At the same time oil is the second check valve 36
Via the pressure port 40 and into the accumulator chamber 22 of the intake valve drive unit 2. The hydraulic pressure in the accumulator chamber 22 causes the piston 23 to descend, resisting the force of the spring 24 and taking the intake valve 21.
Press down to open the valve. At this time, the needle valve 34 receives the valve opening force due to the oil pressure in the variable pressure chamber 38 and the valve closing force due to the oil pressure in the oil pressure chamber 39. The high pressure oil from is sent to the intake valve drive unit 2.

FIG. 2 shows the behavior of each member of the above apparatus. That is, the lift of the plunger 13 of the hydraulic pump 1, the energization signal of the piezo actuator 31, the pressure of the variable pressure chamber 38, the hydraulic chamber 39 and the accumulator chamber 21, the lift of the needle valve 34,
And the relationship between the lift of the intake valve 21 and the lift.

As the plunger 13 of the hydraulic pump 1 is lifted, oil flows into the variable pressure chamber 38, the hydraulic chamber 39, and the accumulator chamber 22 as shown by the state K, and the pressures in the variable pressure chamber 38, the hydraulic chamber 39, and the accumulator chamber 22 increase. To do. Even if the pressure in the pipe 14 is lowered by the suction return valve 11 after the discharge stroke of the hydraulic pump 1 is completed, the first check valve 35 and the second check valve 36 exist, so that the variable pressure chamber 38 and the hydraulic chamber 39 The pressure remains elevated. With these operations, the intake valve 21 opens and maintains the valve open. At this time, since the pressure in the variable pressure chamber 38 and the pressure in the hydraulic chamber 39 are the same in the needle valve 34, the spring 42
Keeps the valve closed.

When the piezo actuator 31 is energized to close the intake valve 21 (point A), the piezo actuator 31
31 extends and pushes the hydraulic piston 32 downward. Therefore, the volume of the variable pressure chamber 38 decreases, and the pressure increases accordingly.
(Point B) Along with this, the needle valve 34 is pushed downward and opens. (Point C) Then, the oil in the hydraulic chamber 39 and the accumulator chamber 22 is caused to flow out to the relief port 41.
If the pressure in the hydraulic chamber 39 drops due to oil spill,
The difference from the hydraulic pressure of 38 increases and the needle valve 34 further descends. (Point D) The intake valve 21 is closed because the oil in the accumulator chamber 22 is relieved as the hydraulic pressure decreases. And during this time, the needle valve 34
When the check valve 343 comes into contact with the protrusion 431 and is pushed open, the hydraulic chamber 39 and the variable pressure chamber 38 are electrically connected. Then, the needle valve 34 repeatedly moves up and down until the pressure is balanced according to the force of the spring 42. In this way, the needle valve 34 repeats the opening and closing of the check valve 343 and the accumulator chamber 22.
Relieve the oil inside. (Point E) After closing the intake valve 21, close the piezo actuator 31
When the voltage applied to is released (point F), the piezo actuator 31 contracts, and as a result, the hydraulic piston 32 rises under the biasing force of the disc spring 321. Therefore, the volume of the variable pressure chamber 38 is reduced and the hydraulic pressure is reduced (point G), whereby the needle valve 34 is raised and closed. (H point) The next cycle is prepared by setting the above state.

By controlling the timing of applying the voltage to the piezo actuator 31 in this way, it is possible to control the timing of closing the intake valve 21.

Furthermore, the feature of this example is that the needle valve 34 and the check valve 34
By providing 1, the opening of the needle valve 34 can be maintained while reducing the pressure in the variable pressure chamber 38.

Here, even if the check valve 343 is not provided,
Since the oil in the variable pressure chamber 38 is filled with the hydraulic pump 1 at the maximum pressure that has been pumped, the pressure in the variable pressure chamber 38 rises when a voltage is applied to the piezo actuator 31. Therefore, the valve in the first cycle can be opened and the oil in the accumulator chamber 22 can be relieved. However, the needle valve
A problem occurs when closing 34 for the next cycle.
That is, even if the voltage of the piezo actuator 31 is released and the needle valve 34 is suctioned upward and the valve is closed, the hydraulic pressure in the hydraulic chamber 39 has dropped, so until the valve is closed,
It becomes impossible to suck the needle valve 34.

On the other hand, in the case of this example, since the pressures of the variable pressure chamber 38 and the hydraulic chamber 39 can be maintained at substantially the same pressure, the piezo actuator 31 can open and close the needle valve 34.
It can be reliably maintained by applying and releasing the voltage.

As described above, according to this example, since the opening / closing state of the intake valve 21, particularly the valve closing timing can be set appropriately, the timing is controlled according to the engine speed and the load, and the inertial effect of the intake air is reduced. It can be greatly improved. Further, by appropriately controlling the lift amount of the intake valve 21, it is possible to increase the lift amount to reduce pumping loss, and conversely, to reduce the lift amount to enhance the swirl effect.

FIG. 3 shows a second embodiment of the control method.

The difference from the first embodiment shown in FIG. 2 is the method of applying a voltage to the piezo actuator 31.

During one cycle, the voltage is applied and released twice.
This allows the needle valve 34 to be opened and then closed once. As a result, it is possible to stop the intake valve 21 in the middle of closing the valve. as a result,
According to this example, it is possible to mitigate the impact caused by the abrupt change of the intake valve 21, and obtain the noise reduction effect.

Similarly, the application of voltage during one cycle is repeated several times,
By controlling the period and the number of times, the needle valve 34 can be opened and closed digitally. As a result, the oil outflow speed of the accumulator chamber 21 can be controlled, and the valve closing speed of the intake valve 21 can be controlled.

The hydraulic control valve 3 of the present invention can be used not only for controlling the opening / closing of the intake valve 21, but also as a general-purpose valve for relieving the oil stored at high pressure or a fuel injection valve.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of the hydraulic control device of the present invention, and FIG.
FIG. 1 is an explanatory diagram showing the operation timing of the device shown in FIG. 1, and FIG. 3 is an explanatory diagram showing the operation timing of another example of the device according to the present invention. 1 …… hydraulic pump, 3 …… hydraulic control valve, 31 …… piezo actuator, 32 …… hydraulic piston, 34 …… needle valve, 35 …… first check valve, 36 …… second check valve, 3
8 …… Transformer room, 39 …… Hydraulic room, 41 …… Relief port.

Front page continuation (72) Inventor Yukihiro Natsuyama 14 Iwatani, Shimohakaku-cho, Nishio-shi, Aichi Japan Auto Parts Research Institute, Inc. (56) References JP 61-52473 (JP, A) JP 61- 180075 (JP, A) JP 61-266886 (JP, A) Actually opened 61-140105 (JP, U) Actually opened 61-37410 (JP, U)

Claims (3)

[Claims] 1. A variable pressure chamber and a hydraulic chamber for temporarily holding a fluid are formed, and a passage for guiding a fluid pumped intermittently from a hydraulic pump to the variable pressure chamber and the hydraulic chamber is formed. And a housing provided with a relief port for relieving the fluid in the hydraulic chamber to the outside, and the housing is housed in the housing and defines the variable pressure chamber, and expands and contracts according to the applied voltage. A piezo actuator that expands and contracts the volume of the variable pressure chamber, a needle valve that is reciprocally provided in the housing and receives pressure in the variable pressure chamber and the hydraulic chamber to connect or disconnect the hydraulic chamber and the relief port, It is provided in the middle of the passage to allow the movement of the fluid from the hydraulic pump to the variable pressure chamber and to prevent the movement of the fluid from the variable pressure chamber to the hydraulic pump side. And a second check valve for permitting movement of fluid from the hydraulic pump to the hydraulic chamber and preventing movement of fluid from the hydraulic chamber to the hydraulic pump, and a voltage of the piezoelectric actuator. A fluid pumped from the hydraulic pump is pumped to each of the variable pressure chamber and the hydraulic chamber via the passage through the first and second check valves,
When the fluid pressure in the hydraulic chamber is higher than the fluid pressure in the variable pressure chamber, the needle valve shuts off the hydraulic chamber and the relief port and applies a voltage to the piezo actuator to reduce the fluid pressure in the variable pressure chamber. When the pressure is higher than the fluid pressure in the hydraulic chamber, the needle valve communicates the hydraulic chamber with the relief port, and the needle valve has a passage communicating with the variable pressure chamber and the hydraulic chamber, and is disposed in the middle of the passage. The hydraulic chamber of the housing, which is provided and has a third check valve capable of moving fluid from the hydraulic chamber to the variable pressure chamber and blocking movement of fluid from the variable pressure chamber to the hydraulic chamber, Of the portion, the opposite surface of the third check valve has a protrusion forcibly opening the third check valve as the third needle valve opens. Hydraulic control device according to symptoms. 2. The control means performs energization and deenergization of the piezo actuator at predetermined intervals so that the fluid pressure in the hydraulic chamber drops to a predetermined value. The described hydraulic control device. 3. The hydraulic control apparatus according to claim 2, wherein the control means detects the engine speed or the accelerator angle to control the energization of the piezo actuator.