JPS59206671A - Control valve apparatus having electrostriction element - Google Patents

Abstract

PURPOSE:To stabilize the fuel injection amount by shifting the operation body of a control valve apparatus which is constituted of an electrical strain element, according to the elongation and contarction of the electrical strain element and making the effective stroke of a piston which corresponds to the max. length of shift smaller than the whole stroke of the piston. CONSTITUTION:The fuel supplied by a feed pump 3 flows into a space 71 and fills also a space 11. An electrical strain element 5 elongates or contracts when a voltage is applied, and for example, when +500V is supplied, a piston 10 shifts downward by 50mum against the repulsive force of a spring 111. Since the upper edge surface of a needle body 22 is positioned above by the ring-shaped groove 19 of a cylinder 17 at this time, the pressure of the fuel in the space 11 increases to the hydraulic pressure over the repulsive force of a spring 24, and the needle body 22 is pushed downward. Though a clearance is provided between the slidable part 18 of the cylinder 7 and a piston part 221, fuel leak through the clearance is prevented, since transfer of the piston 10 is performed at high speed, and the needle body 22 is pushed downward, and the fuel in the space 71 is jetted-out.

Description

[Detailed description of the invention] Technical field The present invention relates to an injection valve device using an electrostrictive element.

The device according to the invention is used, for example, for asynchronous injection valves in motor vehicle engines. It is particularly used when it is desired to obtain a stable injection amount regardless of changes in the amount of strain in the electrostrictive element, such as changes in the amount of strain due to temperature.

BACKGROUND ART In general, there is a growing need for electronic control to improve the response of automobiles, and injection valves play an important role in this. Conventionally, it has been proposed to use an electrostrictive element as a high-speed response actuator, but the amount of strain in this element generally changes depending on the temperature, and the amount of injection in injection valves that directly convert the amount of strain into the amount of injection changes. There is a problem.

The present inventor has proposed that even if the amount of strain of the electrostrictive element changes, the amount of strain 1
We focused on the fact that the injection amount can be stabilized by not converting 00% to needle lift but by taking the invalid strain amount to maintain a constant needle lift.

OBJECTS OF THE INVENTION In view of the problems with the conventional type described above, an object of the present invention is to move an actuating body in accordance with the expansion and contraction of an electrostrictive element, and to increase the effective length of the piston member corresponding to the maximum length of movement of the actuating body. The purpose is to stabilize the fuel injection amount based on the idea that the stroke is smaller than the total stroke of the piston member.

Structure of the Invention In the present invention, an electrostrictive element, a piston member that responds to the expansion and contraction of the electrostrictive element, a pump chamber that is closed by the piston member and filled with fuel, and an end face facing the pump chamber are provided. The actuating body moves according to the expansion and contraction of the electrostrictive element, and the effective stroke of the piston member corresponding to the maximum length of movement of the actuating body is longer than the entire stroke of the piston member. A control valve device using an electrostrictive element is provided, which is characterized by being small.

Embodiment A control valve device using an electrostrictive element as an embodiment of the present invention is shown in FIG. The system of FIG. 1 is of the type in which the fuel is in an uncompressed state during operation. The characteristics of the device of FIG. 1 are shown in FIG.

In the apparatus shown in FIG. 1, 1 is a fuel tank, and a feed line is formed in this order: a pipe 2, a feed pump 3, a pipe 4, and an electrostrictive control valve Cv. The control valve Cv mainly includes an electrostrictive element 5
, a casing 6, a cylinder 7, a valve set 8, a holder 9, a piston 10, and a spring 111.

An electrostrictive element 5, a piston 10, and a spring 111 are housed in a space 12 in the center of the casing 6. Furthermore, a takeout portion 132 for a lead wire 131 for receiving the voltage from the biasing circuit 13 is formed in the upper center of the electrostrictive element 5 .

Furthermore, a fuel inlet port 15 and a fuel overflow boat 16 are formed in the casing 6, and the inlet boat 15 is connected to the piping 4.
The overflow boat 16 is connected to the piping 17, respectively. A throttle 171 is provided in the middle of the pipe 17 to set an appropriate feed pressure.

The cylinder 7 has a sliding part 18 formed in the center thereof, and a ring-shaped groove 19 is provided in a part of the sliding part 18. The ring-shaped groove 19 communicates with the inlet boat 15 by a boat 20 and with the overflow boat 16 by a boat 21 . The valve set 8 includes a needle body 22, a valve body 23, a spring 24, and a spring support plate 25.

The upper part of the needle body 22 forms a piston part 221, and the lower end forms a seat part 222 in the shape of an outer valve. The seat portion 222 is connected to the seat portion 2 of the valve body 23 by the spring 24.
31 to seal the fuel. A spring chamber 232 is located above the seat portion 231 of the valve body 23 .

At the center of the bottom of the cylinder 7 is a spring support plate 25.
A space 71 is provided in which the items are stored.

The outer periphery of the upper end surface 72 of the cylinder 7 is in close contact with the lower end surface of the casing 6 to maintain a seal, and the center portion is connected to the spring 1.
The piston 10 and the electrostrictive element 5 can be urged upward as a seat 11.

The lower end surface 73 of the cylinder 7 is the upper end surface 2 of the valve body 23.
33 and maintains a seal. Furthermore, the boat 26 connected to the boat 20 of the cylinder 7 is the boat 2 of the valve body 23.
7 and opens into the spring chamber 232 of the boat 27 . The casing 6, cylinder 7, and valve body 23 are integrally fastened by a holder 9.

The installation space 11 of the spring 111 becomes a pump chamber for pushing the needle 22 downward. When the seat portion 222 of the needle 22 is seated, the upper end surface of the Piaton portion 221 is positioned above the ring-shaped groove 19. An O-ring 28 for sealing is provided on the outer circumference of the piston 10. Further, the outer diameter of the spring support plate 25 is larger than the inner diameter of the spring chamber 232 to prevent the needle body 22 from overlifting.The operation of the apparatus shown in FIG. 1 will be described below.

The fuel supplied by the feed pump 3 is fed to the inlet boat 1
5, a passage 20, a ring-shaped groove 19, a passage 21, an overflow boat 16 passing through 9, a pipe 17, a boat 26 which is returned to the tank 1 and is branched from the boat 20;
3 flows into the r+ space 71 through the boat 27, and at the same time flows through the gap between the piston ff1i221 of the needle body 22 and the cylinder sliding part 18 to the space 11 serving as the pump chamber.
It is also filled with fuel.

The valve opening pressure is set by the spring 24 so that fuel does not leak from the seat portion 222 of the needle body 22 with this feed pressure. The electrostrictive element 5 expands and contracts when a voltage is applied. For example, when +500V is applied, the axial inner core elongates by 50 μm. Therefore, in the above state, +500V is applied to the electrostrictive element 5.
When applied, the piston 10 is displaced 50 μm downward by the reaction force of the spring 111.

At this time, the needle body 22 is inserted into the ring-shaped groove 19 of the cylinder 7.
Since the upper end surface is located upward, the fuel in the space 11 increases to a hydraulic pressure greater than the reaction force of the spring 24 and pushes the needle body 22 downward.

A slight clearance is set between the sliding part 18 of the cylinder 7 and the piston part 221 of the needle body 22, but since the piston 10 moves at a high speed of several tens of microseconds, there is almost no fuel leakage from the clearance and the needle body 22 is pushed downward. If the needle body moves downward even slightly, the seal on the seat portion 222 is released and the fuel in the space 71 is injected outward in a conical shape.

In other words, the time when high voltage is applied to the electrostrictive element 5 becomes the injection start time. If the piston 10 moves further downward, the needle body 22 also moves further downward. When the upper end surface of the needle body matches the ring-shaped groove 19 and the hydraulic pressure in the space 11 is conducted to the boat 20 or 21 side, it becomes impossible to push the needle body 22 downward even if the piston 1o moves further. At this time, the needle body 22 reaches its maximum lift.

Thereafter, when the high voltage application to the electrostrictive element 5 is stopped and the voltage is lowered to, for example, Ov, the oil pressure in the space 11 drops instantly and the needle body 22 is returned to its original position by the reaction force of the spring 24. This is repeated below.

The device shown in FIG. 1 is a non-compression type control valve device that controls the amount of movement (lift) to be constant. In the device shown in FIG. 1, as shown in FIG. 2, when the piston starts to move, the needle body 22 opens, and the maximum lift occurs when the ring-shaped groove 19 and the upper end surface of the second needle body coincide with each other. The lift of this needle body always takes a constant value.

In FIG. 2, the horizontal axis represents the voltage E, and the vertical axis represents the piston stroke L. The total stroke of the piston is L(TO
T), the effective stroke is given by L(EF'F). For example, even if the elongation changes due to the temperature characteristics of the electrostrictive element, if the effective lift of the needle body 22 is set below the minimum elongation amount, a constant lift can be obtained without the influence of temperature, and a constant injection amount can be obtained. is obtained. Since the injection amount in one operation is constant, the injection amount is controlled by frequency.

Another embodiment of the invention is shown in FIG. The device shown in FIG. 3 is of the type in which the fuel is compressed during operation. The characteristics of the device shown in FIG. 3 are shown in FIG.

In the device shown in FIG. 3, the electrostrictive control valve Cv mainly includes an electrostrictive element 5, a casing 6, a cylinder 7, a valve set 8, a holder 9, a piston 10, a spring III,
If-12,)/su/g113〃・ra is warped. The casing 6, □, and the arrangement holder 9 for the electrostrictive element 5 are the same as those in the apparatus shown in FIG.

The cylinder 7 has a sliding part 18 formed in the center thereof, and a ring-shaped groove 19 is provided in a part of the sliding part 18. 1 non-groove 19 communicates with the inlet port 15 by the boat 20;
It is in communication with Oat's Flow Boat 16. The valve set 8 includes a needle body 121, a valve body 23,
It consists of a spring 24 and a spring support plate 124.

The lower end of the needle body forms a seat portion 1211 in the shape of an outwardly opening valve, and is pressed against the seat portion 231 of the valve body 23 by a spring 24 to seal the fuel. The upper part of the seat portion of the valve body 23 is a pump chamber 232 that also serves as a housing for the spring 113. □The upper end of the spring 113 contacts the lower end surface of the spool body 32 and urges the spool body 32 upward.

The upper surface of the spool body 32 is in contact with the stopper portion 101 of the piece stone 10 during assembly.

A ring-shaped groove 321 is formed in a part of the sliding portion of the spool body 32, and communicates with the pump holder 232 through a horizontal hole 322 and a vertical hole 323. During assembly, the ring-shaped groove 321 is installed so as to overlap the ring-shaped groove 19 of the cylinder 7.

A convex portion 324 having a diameter smaller than the diameter of the sliding portion 18 of the cylinder 7 is provided above the spool body 32, and its shoulder portion 325 is formed so as not to overlap the ring-shaped groove 19 during assembly. Furthermore, when the ring-shaped groove 321 moves downward by an appropriate stroke... When the shoulder 325 moves downward, the ring-shaped groove 19
The dimensional relationship is such that it matches. Spring 111
The installation space 11 is a first pump chamber for pushing the spool body downward.

The operation of the FIG. 3 apparatus will now be described.

The fuel supplied from the feed pump 3 is transferred to the pipe 4, the inlet port 15, the port 20, the ring groove 19, the boat 21.
It passes through the overflow port 16 and returns to the pump, and enters the groove 321 of the spool body 32 from the ring-shaped groove 19, passes through the horizontal hole 322 and the vertical hole 323, and enters the second pump chamber 232.

At the same time, fuel enters the first pump chamber 11 from the gap between the cylinder sliding portion 18 and the spool body 12 above the ring-shaped groove 19.

In this state, the seat portion 1211 of the needle body 121
is pressed upward by the spring 24 to seal the fuel in the second pump chamber 232. Furthermore, spring 11
3 urges the spool body 32 upward, and the piston 1
The stopper portion 101 of 0 and the upper end surface of the spool body are in contact with each other.

When +500V is applied to the electrostrictive element 5, the piston 10 moves downward, the oil in the first pump chamber 11 is moved, and the spool body 32 begins to move downward.

When the ring-shaped groove 321 of the spool body 32 is removed from the ring-shaped groove 19 of the cylinder, the second pump chamber 232 becomes a pressure chamber in which oil cannot move.

The first pump chamber 11 moves the hespool body further downward even as the pressure increases due to the expansion of the electrostrictive element 5. Second
When the pressure in the pump chamber 232 exceeds the opening pressure of the valve set 8, the needle body 121 lifts and the fuel in the second pump rim 232 is injected in a conical shape.

The spool body 32 still moves downward due to the movement of the piston 10, but when the upper shoulder 325 of the spool body matches the ring-shaped groove 19 of the cylinder, the oil pressure in the first port chamber 11 is relieved toward the boat 21. Therefore, it becomes impossible to move the spool body 12 downward ψj1 any further. The spool body 32 moves downward due to the movement of oil, and the stopper portion 101 and the upper end surface of the spool body are not always in close contact with each other.

When the high voltage applied to the electrostrictive element 5 is released, it contracts, so the spool body 32 is urged by the spring 113 and moves upward, stopping at the stopper portion 101. This poetic 2nd pump room 23
Fuel flows into 2, and this process is repeated thereafter.

In the device shown in FIG. 3, the stroke of the spool body 32 is also determined by the dimensional relationship between the ring-shaped groove 19 of the cylinder 7, the ring-shaped groove 321 of the spool body 12, and the shoulder 325. The stroke of the spool body 32 that pumps the bo/b chamber 232 is always constant, and therefore the discharged fuel is also constant.

In the device shown in Fig. 1 and the device shown in Fig. 3, the piston stroke is amplified by a needle body or spool body with a diameter smaller than 1:9, and a part of the stroke contributes to the injection as an effective stroke. There is. In the apparatus shown in FIG. 1 and the apparatus shown in FIG. 3, injection amount control is performed by frequency control.

Effects of the Invention According to the present invention, a control valve device using an electrostrictive element in which the amount of fuel injection is stabilized can be obtained.

[Brief explanation of drawings]

Fig. 1 is a diagram showing a control valve device using an electrostrictive element as an embodiment of the present invention, Fig. 2 is a diagram showing the operating characteristics of the device shown in Fig. 1, and Fig. 3 is a diagram showing another embodiment of the invention. FIG. 4 is a diagram showing the operating characteristics of the device shown in FIG. 3. (Explanation of symbols) 1...Fuel tank, 2...Piping, 3...Feed pump, 4...Piping, 5...Electrostrictive element, 6...Cool tank, 7...Cylinder , 71...space, 7
2... Upper end surface, 73... Lower end surface, 8... Valve set, 9... Holder, 10... Piston, 11...
...Spring installation space, 111...Spring, 1
2... Central space, 13... Biasing circuit, 131
... Lead wire, 132 ... Lead wire extraction part, 15
... Fuel inlet boat, 16 ... Overflow boat, 17 ... Piping, 171 ... Throttle, 18 ... Sliding part, 19 ... Ring-shaped groove, 20 ... Boat, 22
... Needle body, 221 ... Piston part, 222.
... Seat part, 23... Valve body (,231-...
Seat portion, 232...Spring chamber, 233...Upper end surface, 24...Spring, 25...Spring support plate, 26.27...Boat, 28...0 ring, 32... Spool body, CV...electrostrictive control valve. Patent Applicant Japan Auto Parts Research Institute Co., Ltd. Patent Application Agent Akira Aoki Patent Attorney Kazuyuki Nishidate Patent Attorney Masashi Matsushita Akira Yamaguchi Figure 1 Figure 2 → E Figure 3 → F

Claims (1)

[Scope of Claims] 1. An electrostrictive element, a piston member that responds to the expansion and contraction of the electrostrictive element, a pump chamber that is closed by the piston member and filled with fuel, and an operation in which the end face faces the pump chamber. the actuating body moves according to the expansion and contraction of the electrostrictive element, and the effective stroke of the piston member corresponding to the maximum length of movement of the actuating body is smaller than the total stroke of the piston member. A control valve device using an electrostrictive element, characterized in that: 2. The actuating body is a needle body, and the actuating body moves according to the expansion and contraction of the electrostrictive element of the actuating body, and the actuating body starts moving at the same time as the piston member starts moving, injects fuel, and causes the piston member to move. 2. The device according to claim 1, wherein the hydraulic pressure in the pump chamber facing the piston member is shifted to a low pressure side during the movement of the actuating body, so that the movement of the actuating body is restricted. 3. The actuating body is a spool body, and a valve set is further disposed opposite to the spool body, and the movement of the actuating body according to the expansion and contraction of the electrostrictive element occurs simultaneously with the start of movement of the piston member. The actuating body starts moving, and after moving a certain length,
The pressure of the fuel between the nuclear actuating body and the valve set is increased to inject the fuel from the valve center, and after further movement for a certain distance, the hydraulic pressure in the pump chamber facing the piston member is reefed to the low pressure side and the fuel is injected. 2. The device according to claim 1, wherein the device is configured to terminate the process.