JP2001115948A - Pump device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a stable output characteristic. SOLUTION: In a pump device 1 wherein a hydraulic liquid in a reservoir 2 is pre-loaded, and which is provided with a delivery port 14 connected to an actuator 3, a pump part 1a wherein a piston 9 is housed in a housing 6, a piston driving part 1b for delivering and intaking a fluid from/to the pump part 1a by performing reciprocating motion of the piston 9 to the housing 6, and the reservoir 2 for reserving the fluid as well as connecting to the suction port 13 of the pump part 1a, the hydraulic liquid in the reservoir 2 is pre-loaded by air pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pump device, and more particularly to a pump device capable of obtaining stable output characteristics.

[0002]

2. Description of the Related Art In recent vehicles, intelligent brake functions such as an anti-lock brake system and a traction control system have been actively developed. With the advance of such intelligent technology, for example, electric pumps and miniaturization of pumps as hydraulic pressure sources incorporated in brake devices and the like have become indispensable.

FIG. 2 shows a conventional well-known electric pump device applied to such an application, for example, a brake device (JP-A-7-16327, JP-A-8-334).
No. 082). The electric pump device 32 includes a pump section 32a that discharges hydraulic oil by reciprocating a piston 31 housed in a housing 30, and a solid element that can electrically control expansion and contraction as a driving source for reciprocating the piston 31. , For example, a piston drive unit 32b using a giant magnetostrictive element 33. Discharge port 34 of pump section 32a
Is connected to a pressure chamber of a brake actuator 36 via a discharge check valve 35. On the other hand, the pump unit 32
The suction port 37 a is connected to an oil chamber 41 of a reservoir 40 via a suction check valve 38. The brake actuator 36 is connected to a reservoir 40 via a normally closed electromagnetic switching valve 39.

In this electric pump device 32,
The current supplied from the controller 42 is supplied to the solenoid coil 4
When the voltage is applied to 3, the supply and stop of the current are repeated to cause the giant magnetostrictive element 33 to expand and contract, and the piston 31 reciprocates accordingly. When the piston 31 is reciprocated, hydraulic oil is sucked from the oil chamber 41 of the reservoir 40 through the suction check valve 38 into the oil chamber 44 of the pump portion 32a, and the discharge check valve 35 is further discharged from the oil chamber 44. The pressure is sent to the pressure chamber of the brake actuator 36 through the pressure chamber. The hydraulic oil pumped into the pressure chamber of the brake actuator 36 activates the brake pad in the brake actuator 36 and brings the brake pad into contact with the brake disc to obtain a braking force. On the other hand, to release the braking force, the current supply to the giant magnetostrictive element 33 is cut off, and the electromagnetic switching valve 3 is switched off.
By actuating 9 to open the pipeline, the hydraulic oil in the pressure chamber of the brake actuator 36 is returned to the oil chamber 41 of the reservoir 40. Therefore, the brake actuator 36
Is released.

[0005]

By the way, in the electric pump device 32, a piston 45 is disposed in the oil chamber 41 of the reservoir 40, and the piston 45 is urged by a coil spring 46. A preload is applied to the hydraulic oil in 41 to prevent air from entering the hydraulic circuit.

However, the brake actuator 3
6, the piston of the brake actuator 36 moves forward with the wear of the brake pad, and the amount of hydraulic oil in the brake actuator 36 increases. As a result, the amount of oil in the oil chamber 41 of the reservoir 40 decreases and the coil spring 4
6 extend, and its urging force decreases. Therefore, in the electric pump device 32, the brake actuator 36
In this case, the pump efficiency may be changed due to the wear of the brake pad in the above.

[0007] The present invention has been made in view of the above circumstances,
It is an object of the present invention to provide a pump device capable of always obtaining stable output characteristics regardless of the amount of oil in a reservoir.

[0008]

According to the present invention, there is provided a pump apparatus comprising: a discharge port connected to an actuator; a pump section having a piston housed in a housing; A piston drive unit that causes the pump unit to discharge and inhale hydraulic oil by reciprocating a piston; and a reservoir that is connected to a suction port of the pump unit and stores the hydraulic oil. In the pump device in which the hydraulic oil is pressurized, the hydraulic oil in the reservoir is pressurized by gas pressure.

[0009] According to the above configuration, since the hydraulic oil in the reservoir is pre-pressed by the gas pressure, even if the hydraulic oil in the reservoir decreases due to wear of the brake pad in the brake actuator, for example, even if the hydraulic oil in the reservoir decreases. A constant pressure can always be applied to the hydraulic oil, thereby eliminating the possibility that the pump efficiency fluctuates.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a pump device according to the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a pump device according to an embodiment of the present invention.

The pump device 1 comprises a pump portion 1a, a piston driving portion 1b, a reservoir 2, actuators such as a brake device, a pipeline connecting them, an electromagnetic switching valve 5 interposed in the pipeline 4, and the like. Have been.

The piston driving section 1b includes a giant magnetostrictive element 7 in a housing 6 formed in a bottomed shape. The giant magnetostrictive element 7 is surrounded by a solenoid coil 8, and a magnetic field excited by the solenoid coil 8 It is located in. The pump section 1a has a piston 9 disposed at the tip of the giant magnetostrictive element 7, and the piston 9 is pressed against the tip of the giant magnetostrictive element 7 by a spring 10. The piston 9 defines an oil chamber 11 in the housing 6. An end wall 12 for closing the opening end of the housing 6 is formed with a suction port 13 and a discharge port 14 for hydraulic oil.
3, the discharge port 14 is provided with a discharge check valve 20 and a suction check valve 21, respectively. The giant magnetostrictive element 7 is controlled by the control device 15 by supplying / cutting off a current applied to the solenoid coil 8.

The reservoir 2 is provided with a piston 16, and the piston 16 allows the oil chamber 17 and the pneumatic chamber 1 to move.
8 is defined. The pneumatic chamber 18 is connected to a large-capacity pneumatic source, for example, a large-capacity air tank 19, and the piston 16 is constantly urged at a constant pressure in a direction to reduce the oil chamber 17. That is, the oil chamber 17 of the reservoir 2 is pre-pressed by the air tank 19 at a constant pressure.

The actuator 3 includes a return spring (not shown), and is operated by hydraulic oil fed from the pump body 1.

The discharge port 14 of the pump section 1a is connected to an oil chamber (not shown) of the actuator 3 through a pipe 4a. The oil chamber of the actuator 3 passes through a pipe 4b with an electromagnetic switching valve 5 interposed therebetween, and
The oil chamber 17 of the reservoir 2
Is connected to the suction port 13 of the pump body 1 through the conduit 4c. The discharge check valve 20 is provided in the pump section 1a.
Only the discharge of hydraulic oil from the suction check valve 21
Allows only the suction of the hydraulic oil to the pump section 1a. The electromagnetic switching valve 5 interposed in the pipe 4b is a normally-closed switching valve, and is opened by a signal from the control device 15 described above.

In the pump device 1 configured as described above,
In a non-operating state of the actuator 3, for example, in a non-braking state in the case of a brake device, the supply of current to the giant magnetostrictive element 7 is stopped, and the electromagnetic switching valve 5 closes the pipeline 4b. In order to operate the actuator 3, a current of a predetermined frequency is supplied from the control device 15 to the solenoid coil 8.
, The giant magnetostrictive element 7 is expanded and contracted in accordance with a predetermined frequency, and the piston 9 is reciprocated accordingly. When the piston 9 moves forward, the oil chamber 11 is reduced, so that the operating oil in the oil chamber 11 is discharged from the discharge check valve 20.
To the actuator 3 to operate the actuator 3. When the piston 9 moves backward, the oil chamber 11 is enlarged, so that the hydraulic oil is sucked into the oil chamber 11 from the reservoir 2 via the suction check valve 21.

When the operation of the actuator 3 is released, the electromagnetic switching valve 5 is operated by a signal from the control device 15 to open the conduit 4b.
Hydraulic oil inside is returned to the reservoir 2 via the electromagnetic switching valve 5.

In the pump device 1, since the oil chamber 17 of the reservoir 2 is pre-pressed at a constant pressure by the air tank 19, the operating oil in the oil chamber 17 decreases with the wear of the brake pad in the brake actuator 3. Even
A constant pressure can always be applied to the hydraulic oil in the oil chamber 17, thereby eliminating the possibility that the pump efficiency fluctuates.

In the above embodiment, the air tank 19 is used as a pneumatic pressure source.
For example, in a railway vehicle, a large-capacity air tank for opening and closing doors and an air suspension is used without using the fuel cell 9, and when the pressure of this air tank decreases, a constant pressure is maintained by a compressor. In the above-described embodiment, the volume of the pneumatic chamber 18 is substantially increased by connecting the large-capacity air tank 19 to the pneumatic chamber 18. Of course, the size may be expanded.

In the above embodiment, the giant magnetostrictive element 7 is used for the driving section 1b. However, the present invention is not limited to the giant magnetostrictive element 7, but may be, for example, a piezoelectric element. Further, as the gas in the present invention, an inert gas such as a nitrogen gas may be employed.

[0021]

As described above, in the pump device according to the present invention, since the hydraulic oil in the reservoir is pre-pressed by the gas pressure, for example, the hydraulic oil in the reservoir is reduced due to wear of the brake pad in the brake actuator. Even if the pressure decreases, a constant pressure can always be applied to the working oil of the reservoir, thereby eliminating the possibility that the pump efficiency fluctuates.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of a pump device according to the present invention.

FIG. 2 is a configuration diagram showing a conventional pump device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pump apparatus 1a Pump part 1b Piston drive part 2 Reservoir 3 Actuator 4, 4a, 4b, 4c Pipe line 5 Electromagnetic switching valve 6 Housing 7 Giant magnetostrictive element (solid element) 8 Solenoid coil 9 Piston 10 Spring 11 Oil chamber 12 End wall Material 13 Suction port 14 Discharge port 15 Control device 16 Piston 17 Oil chamber 18 Pneumatic chamber 19 Air tank (pneumatic source) 20 Discharge check valve 21 Suction check valve

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F16D 65/20 F-term (Reference) 3D046 CC02 EE01 LL14 LL23 LL29 LL40 LL46 LL51 3H070 AA01 BB07 BB17 CC37 DD66 DD96 3H075 AA05 BB03 CC16 CC40 DA09 DA16 DB08 3J058 AA77 AA78 AA87 BA41 CC03 CC16 FA01

Claims (1)

[Claims] A discharge port connected to the actuator;
A pump unit in which a piston is housed in a housing, a piston drive unit that causes the pump unit to discharge and suction hydraulic oil by reciprocating the piston with respect to the housing, and a pump unit connected to a suction port of the pump unit. And a reservoir for storing the hydraulic oil, wherein the pump is pressurized with the hydraulic oil in the reservoir, wherein the hydraulic oil in the reservoir is pressurized by gas pressure. Pumping equipment.