JPH0375792B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrostrictive fluid control valve for controlling pressure fluid.

[Prior art]

In conventional control valves for controlling pressure fluid, the valve body thereof is usually driven by a solenoid. However, such control valves do not sufficiently meet the demand for high-speed response. Therefore, research has begun on using piezos (electrostrictive elements) as drive devices that can respond to high-speed responses in poppet valves. As an example, a piezoelectric fluid injection pump disclosed in Japanese Patent Publication No. 44-6659 is known.

[Problem to be solved by the invention]

However, in the above conventional example, after the poppet valve is opened, the fluid pressure within the pump chamber gradually decreases, and when the pressure becomes lower than a predetermined pressure, the valve is closed by the spring force. As described above, the conventional example has a problem in that the closing timing of the poppet valve cannot be arbitrarily controlled.

The present invention has been made in view of the above points,
It is an object of the present invention to provide an electrostrictive pressure control valve that can arbitrarily control the closing timing of a valve body.

[Means to solve the problem]

In order to achieve the above object, an electrostrictive fluid control valve according to the present invention includes an electrostrictive actuator, a chamber filled with fluid, and an internal volume of which changes in accordance with expansion and contraction of the electrostrictive actuator. a pressure chamber; a valve body that receives fluid pressure generated in response to a change in internal volume of the pressure chamber at its end face and reciprocates between a communication position and a blocking position; and a valve body that moves back and forth between a communicating position and a blocking position; a fluid passage that is closed by the valve body when the valve body is in the communication position and opened by the valve body when the valve body is in the communication position; and a throttle passage that branches from the fluid passage and communicates with the pressure chamber, the throttle passage is formed at least in part by the valve body, and when the valve body is in the communicating position, the throttle passage formed by the valve body is formed by a change in the position of the valve body. It is configured to be closed and opened by a change in the position of the valve body when the valve body is in the blocking position.

[Effect]

With the above configuration, when the fluid passage is switched to the blocked state by the reciprocating movement of the valve body, the throttle passage is brought into communication, and fluid is supplied to the pump chamber.
On the other hand, when the fluid passage is switched to the communicating state, the throttle passage becomes the blocked state, so the volume of the pump chamber does not change, and the communicating state of the fluid passage is maintained.
In addition, in the present invention, the throttle passage is formed by a part of the valve body, and the communication/blocking state is switched using the reciprocating motion of the valve body, so that the flow of fluid to the pump chamber is reduced. Supply can be performed with a simple configuration.

〔Example〕

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

FIG. 1 is a longitudinal sectional view showing a three-way valve according to an embodiment of the present invention, taken along its central axis.

In the figure, 1 is a three-way valve, which includes a pump 3 operated by an electrostrictive actuator 2, a valve body 6 driven by the operation of this pump 3, and a fluid for controlling or driving the required equipment. A control port 4, a high pressure port 5, and a low pressure port 7 are provided.

The casing of the three-way valve 1 is the casing body 8
The casing actuator 9 and the valve retainer 10 are arranged to face each other with the casing actuator 9 and the valve retainer 10 facing each other, and both the casing actuator 9 and the valve retainer 10 are screwed to the casing body 8 as male threads. Control port 4
The high pressure port 5 is provided in the casing body 8, and the low pressure port 7 is provided in the valve retainer 10.
Two valve units, a high pressure valve unit 11 and a low pressure valve unit 12, are housed within the casing body 8. Both valve units 1
1 and 12 are provided facing each other with a partition wall 13 provided in a nodal shape on the casing body 8 as a boundary. The partition wall 13 has an axial through hole 14, and the through hole 14 and the control port 4 communicate with each other through a passage 15 provided in the partition wall 13 in the radial direction. The high pressure valve unit 11 is composed of a valve body 16 and a valve poppet 17 which is a first valve body. The valve body 16 is cylindrical, has a mirror-finished lower end surface, and is in close contact with the upper end surface of the partition wall 13, which is also mirror-finished. The valve body 16 is connected to the through hole 1 of the partition wall 13.
A through hole is provided so as to be coaxial with 4, and the upper part of this through hole has a larger diameter than the lower part. The small diameter portion 18 of this through hole communicates with the through hole 14 of the partition wall with the same diameter and coaxially. The large diameter portion 19 of the through hole has sufficient clearance (10 μm to 50 μm) to allow the guide portion 20 of the valve poppet 17 to slide thereon. This clearance 19' also functions as a diaphragm, which will be explained later. The small diameter portion 18 and the large diameter portion 19 transition into a conical shape, and this conical portion forms the valve seat 21 . Above the valve seat 21, the large diameter portion 19 is further enlarged into a ring shape to form an oil reservoir 22, which is communicated with the high pressure port 5 through a passage 23. This passage 23
Since the valve body 16 and the partition wall 13 move from the lower end surface of the valve body 16 to the partition wall 13, the relative positions of the valve body 16 and the partition wall 13 are fixed by a dowel pin or the like (not shown). The valve poppet 17 has a large-diameter guide portion 20 and a small-diameter protrusion 24, and the guide portion 20 and the protrusion 24 are continuous in a conical shape. This conical portion forms the first valve portion 25. When the conical part 25 of the valve poppet 17 and the conical part 21 of the valve body 16 come into close contact, the high-pressure valve unit 11 is in a closed state, but at this time, the conical part 25 of the valve poppet 17 is more flush than the conical part 21 of the valve body 16. As a result, the hydraulic pressure of the high pressure port 5 introduced into the oil sump 22 acts upwardly on the valve poppet 17. The protruding portion 24 of the valve poppet 17 has a diameter sufficiently smaller than that of the through hole 14 of the partition wall, and has a diameter of 0.1 to 1 mm.
It protrudes to the middle of the through hole 14 with a clearance of . The tip of the protrusion 24 comes into contact with a similar protrusion 27 of the valve poppet 26 of the low pressure valve unit 12 when the valve lift of the valve poppet 17 becomes 0.1 mm below the maximum.

The low pressure valve unit 12 is composed of a valve poppet 26 which is a second valve element, a valve body 28, and a coil spring 29. The valve body 28 is cylindrical, has a mirror-finished upper end surface, and is in close contact with the lower end surface of the partition wall 13, which is also mirror-finished. It is the valve retainer 10 that exerts this adhesion force, and the valve retainer 10 has a valve body 28 inside it.
is stored. The valve body 28 is provided with a through hole coaxially with the through hole 14 of the partition wall.
The lower part of this through hole has a larger diameter than the upper part. The small diameter portion 30 of this through hole is the through hole 14 of the partition wall.
It communicates with the same diameter and coaxially. Large diameter part 3 of through hole
1 accommodates the large diameter portion 32 of the valve poppet 26 with sufficient clearance (0.1 to 1 mm).
The small diameter portion 30 and the large diameter portion 31 are continuous in a conical shape, and this conical portion forms a valve seat. The valve poppet 26 is composed of a protruding portion 27, a large diameter portion 32, and a spring guide 34 from above. Projection part 2
7 has a sufficiently smaller diameter than the through hole 14 of the partition wall 13, and protrudes to the middle of the through hole 14 with a clearance of 0.1 to 1 mm, and when the low pressure valve unit 12 is opened, the protruding portion of the valve poppet 17 24. The small diameter protrusion 27 and the large diameter part 32 are continuous in a conical shape,
This conical portion forms the second valve portion 35. Conical portion 35 of valve poppet 26 and valve body 2
When the conical portions 33 of 8 are in close contact, the low pressure valve unit 12 is in a closed state. The dimensions of the protrusions 24 and 27 are designed such that the valve lift of the valve poppet 26 is 0.1 to 0.3 mm when the valve poppet 17 is fully closed. The protrusion 27 is the protrusion 2
When the power from 4 is released, valve poppet 26
The force for closing the valve with zero valve lift is provided by the coil spring 29. The coil spring 29 is housed in the large diameter portion 32 of the through hole of the valve body 28, and has an upper end in contact with the valve poppet 26 and a lower end in contact with the valve retainer 10. The lower end of the large-diameter portion 31 of the valve body 28 is closed by the valve retainer 10, and the valve retainer 10 also has a through hole 36 to allow the large-diameter portion 31 and the low-pressure port 7 to communicate with each other. The power for driving the valve poppet 17 up and down in the axial direction to open and close the high-pressure valve unit 11 is hydraulic power, and the guide portion 2 of the valve poppet 17
This hydraulic pressure is applied to the upper end surface of the distance piece 38 by the pump chamber 37.
Supplied via. The distance piece 38 is disc-shaped and has mirror-finished surfaces on both sides, and is housed in the casing body 8 .The lower end surface is in close contact with the upper end surface of the valve body 16 , and the outer periphery of the upper end surface is in contact with the casing actuator 9 . It is pressed and fixed by the outer peripheral wall. The casing actuator 9 has a cylindrical shape with a closed upper end, and houses the electrostrictive actuator 2, the pump piston 40, and the disc spring 41 from above. In this way, the pump 3 is composed of the electrostrictive actuator 2, the pump piston 40, the pump chamber 37, the disc spring 41, and the distance piece 38.

The electrostrictive actuator 2 has a cylindrical shape by laminating about 50 thin (about 0.5 mm) disc-shaped electrostrictive elements. The electrostrictive element is a ceramic called PZT, whose main ingredients are lead titanate-zirconate, and when a voltage of 500V is applied in the thickness direction,
Extends 1μm. If 50 of these are stacked and 500V is applied in the thickness direction of each element, a total elongation of 50 μm can be obtained. If this voltage is removed or a slight negative voltage is applied, the film will shrink by 50 μm and return to its original length. Application and release of the voltage are performed by an external controller via the lead wire 43. The expansion and contraction of the electrostrictive actuator 2 is directly transmitted to the pump piston 40, which compresses the oil in the pump chamber 37 when the electrostrictive actuator 2 expands, and compresses the oil in the pump chamber 37 when the electrostrictive actuator 2 contracts. The pump chamber 37 is expanded by the biasing force 41. The pump chamber 37 has an upper end formed by the lower end surface of the pump piston 40 and a lower end formed by the upper end surface of the distance piece 38. O in the pump piston 40
A ring 42 is provided to prevent oil pressure in the pump chamber 37 from leaking to the electrostrictive actuator 2 side. When the electrostrictive actuator 2 is extended, the valve poppet 17 is in close contact with the valve seat 21, and at this time, the high pressure port 5 is connected to the pump chamber 37.
Hydraulic pressure of, for example, 200 atmospheres is applied to the passage 23,
The oil is introduced through the oil reservoir 22, the clearance or restriction 19' between the large diameter portion 19 of the through hole of the valve body 16 and the guide portion 20 of the valve poppet 17, and the through hole 39 of the distance piece 38. This oil pressure acts on the entire upper end surface of the guide portion 20 of the valve poppet 17 to keep the valve poppet 17 in close contact with the valve seat 21 to keep the high pressure valve unit 11 in the closed state. When the electrostrictive actuator 2 is contracted, the valve poppet 17 is closed to the valve seat 21.
In contrast, the valve is in the maximum lift state, and the upper end surface of the guide portion 20 of the valve poppet 17 is in close contact with the lower surface of the distance piece 38, closing the through hole 39. Therefore, the pump chamber 37 maintains a low pressure state as the pump chamber expands, so the valve poppet 17 receives the high pressure hydraulic pressure supplied from the high pressure port 5 over its entire lower surface and maintains the maximum valve lift state, that is, the high pressure valve unit 11 continues to maintain the open state. In order to fulfill these functions, the upper end surface of the guide portion 20 of the valve poppet 17 is made into a flat surface parallel to the lower surface of the distance piece 38, and is finished with a mirror finish. Further, the through hole 39 of the distance piece 38 is coaxial with the valve poppet 17, and its diameter is made sufficiently smaller than the diameter of the guide portion 20.
The size thereof is preferably approximately half the diameter of the guide portion 20.

Application examples and operations of this embodiment having the above configuration will be described below.

The low pressure port 7 of the three-way valve 1 communicates with the fuel tank 50. The fuel tank 50 contains, for example, light oil as diesel fuel, and the low pressure port 7 is maintained at approximately atmospheric pressure. The high pressure port 5 is connected to an accumulator 51 . Fuel oil from a fuel tank 50 is supplied to the accumulator 51 at 200 atmospheres via a high-pressure pump, a pressure regulator, etc. (not shown). Control port 4
is introduced into the injection nozzle 52. The injection nozzle 52 is of a type known as a complete nozzle, basically consisting of a nozzle body 53 and a nozzle needle 54, and is attached to an internal combustion engine, such as a diesel engine, by a nozzle holder (not shown). The oil pressure supplied from the control port 4 is introduced as a back pressure to the nozzle needle 54 of the injection nozzle 52, and the larger this oil pressure is, the more the nozzle needle 54 acts in the direction of closing the injection port 55 provided in the nozzle body 53. ing. The hydraulic pressure that acts in the direction in which the nozzle needle 54 opens the spout 55 is applied to the accumulator 56.
A fuel reservoir 57 provided in the nozzle body 53
has been introduced to. Fuel oil from the fuel tank 50 is supplied to the accumulator 56 at 150 atmospheres via a high pressure pump, a pressure regulator, etc. (not shown). When the injection nozzle 52 is not supposed to supply fuel to the internal combustion engine, is a positive voltage applied to the electrostrictive actuator 2 of the three-way valve 1?
Alternatively, a slight negative voltage is applied, and the electrostrictive actuator 2 is in a contracted state. The pump chamber 37 is therefore enlarged and the valve poppet 17 leaves the high-pressure valve unit 11 open. At the same time, the valve poppet 26 is released from the actuation force from the valve poppet 17.
The biasing force of the coil spring 29 closes the low pressure valve unit 12. At this time, the high pressure port 5 is in communication with the control port 4, and 200 atmospheres supplied from the accumulator 51 acts as back pressure on the nozzle needle 54 of the injection nozzle 52, so the nozzle needle 54 closes the injection port 55. There is.

At the time when the injection nozzle 52 should supply fuel to the internal combustion engine, for example, when the piston phase is at a crank angle of 10 degrees before the compression top dead center, a positive voltage of 500 V is applied to the electrostrictive actuator 2 of the three-way valve 1. be done. At this moment, the electrostrictive actuator 2 expands, the pump chamber 37 is compressed, and the generated high-pressure hydraulic pressure acts on the valve poppet 17, causing the high-pressure valve unit 1
Close 1. Although this high-pressure oil pressure escapes to the oil reservoir 22 through the throttle 19', the oil pressure does not drop below the oil pressure of the high-pressure port 5, so that the valve can be kept closed.
At the same time, valve poppet 17 is replaced by valve poppet 26.
The low pressure valve unit 12 is pressed down against the coil spring 29 by contacting the protrusion 27 of the low pressure valve unit 12.
open. At this time, the low pressure port 7 is connected to the control port 4 to remove the back pressure of the nozzle needle 54 of the injection nozzle 52, so the nozzle needle 54 is lifted by the oil pressure in the oil reservoir 57, opens the injection port 55, and injects fuel. and supplied to the internal combustion engine. This amount of fuel injection is proportional to the valve opening time of the injection nozzle 52, so after a necessary and appropriate time elapses, for example, 500V is applied to the electrostrictive actuator 2 and 1.5 msec later, -12V is applied to the electrostrictive actuator 2. When a negative voltage is applied, the pump chamber 37 is expanded, the high pressure valve unit 11 opens, and the low pressure valve unit 12
closes. At this time, the pump chamber 37 has a throttle 19'.
A part of the oil in the oil sump 22 is sucked in through the
Since the through hole 39 is immediately closed, there is no problem at all. This causes the injection nozzle 52 to stop injecting fuel.

To further explain the function of the throttle 19' in the above operation, first, when the throttle 19' is extremely small (10 μm or less in clearance), or when the seal is good and there is virtually no throttle, the pump chamber
7 requires a path for introducing working fluid, and it is also necessary to constantly adjust the amount of oil in the pump chamber 37 to compensate for thermal expansion of the casing, unexpected small leakage, etc. On the other hand, since the aperture 19' is an appropriate aperture (10 to 50 μm in clearance), when the electrostrictive actuator 2 is extended,
The hydraulic pressure of the high pressure port 5 is introduced into the pump chamber 37 through this throttle 19', and the amount of oil in the pump chamber 37 is always maintained at a normal level.

In the above embodiment, the hydraulic pressure of the control port 4 acts directly as back pressure on the nozzle needle 54 of the injection nozzle 52, but in actual use, the hydraulic pressure of the control port 4 acts directly on the nozzle needle 54, but in actual use, A stronger force can be obtained by applying the hydraulic pressure of the control port 4 to the piston and applying the force of the piston to the nozzle needle 54. In this case, the oil pressure of the accumulator 51 does not necessarily need to be greater than the oil pressure of the assortment generator 56, and one accumulator can be used in common.

Furthermore, the three-way valve configured as described above can be used not only to control the injection nozzle 52, but also to control any hydraulic equipment that moves forward in response to high pressure and moves back in response to low pressure, or vice versa. Can be used.

However, this three-way valve is not suitable for controlling hydraulic equipment to stop it in the middle of reciprocating motion.

Further, in the above embodiment, the passage connecting the high pressure port 5 and the control port 4 corresponds to the fluid passage of the present invention, and the throttle 19' corresponds to the throttle passage.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to arbitrarily control the closing timing of the valve body, and the supply of fluid to the pump chamber can be realized with a simple configuration. It has excellent effects.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of an embodiment of the present invention. 1... Three-way valve, 2... Electrostrictive actuator, 3
... Pump, 4 ... Control port, 5 ... High pressure port, 6 ... Valve body, 7 ... Low pressure port, 11 ...
High pressure valve unit, 12... Low pressure valve unit, 13... Partition wall, 16, 28... Valve body, 17, 26... Valve poppet, 19'...
Aperture.

Claims (1)

[Scope of Claims] 1. An electrostrictive actuator 2; a pressure chamber 37 whose chamber is filled with fluid and whose internal volume changes in response to expansion and contraction of the electrostrictive actuator 2; and an interior of the pressure chamber 37. A valve body 17 that receives fluid pressure generated in response to a change in volume at its end face and reciprocates between a communicating position and a blocking position; Valve body 17 when closed and in communication position
a fluid passage 22 opened by the fluid passage 22; and a pressure chamber 37 branched from the fluid passage 22.
and a throttle passage 19' communicating with the valve body 17, at least a part of which is formed by the valve body 17, and when the valve body 17 is in the communicating position, the throttle passage 19' communicates with the valve body 17. The throttle passage 19' formed by the valve body 17 is closed by changing the position of the valve body 17, and
An electrostrictive fluid control valve characterized in that the electrostrictive fluid control valve is opened by changing the position of the valve body 17 when the valve body 7 is at the cutoff position.