JP2546801Y2 - pressure switch - Google Patents

Description

[Detailed description of the invention] << Industrial application field >> This invention is provided in a pressure circuit of an oil pump used for a power steering device for an automobile and the like, and a pressure switch which is opened and closed according to a pressure value in the circuit. About

<< Prior Art >> Generally, rotary pumps such as vane pumps driven by an engine are widely used as oil pumps of this type of power steering device, and those pumps usually increase the rotation speed of the engine. Then, the rotation speed of the pump also increases, and the flow rate of hydraulic oil discharged from the pump increases.

On the other hand, in a hydraulic circuit that generates a steering assisting force of a power steering device, the amount of hydraulic oil flowing through the hydraulic circuit normally corresponds to the degree of the steering assisting force generated by the hydraulic circuit. It is desirable to make the steering assisting force relatively large at the time of bottom stop or low-speed running while the vehicle is stopped, and make the assisting force relatively small at the time of high speed.

Therefore, the oil pump of the power steering device needs to supply the hydraulic circuit with a flow rate of hydraulic oil according to a desired degree of assistance without being affected by the rotation speed or the pressure fluctuation of the input portion of the hydraulic circuit. There is a flow control valve with a so-called flow-down function that reduces the amount of hydraulic oil supplied to the hydraulic circuit when the rotation speed of the oil pump exceeds a predetermined value. When the load increases and the pressure in the hydraulic circuit becomes equal to or higher than a predetermined value, and the engine speed decreases, engine stall occurs. And is installed.

Conventionally, as this type of pressure switch, for example,
The thing as described in 63-129934 is known.

This conventional pressure switch comprises a switch housing,
A fixed terminal fixed to one end of the switch housing, a movable terminal movably provided in the switch housing, and a movable terminal being elastically urged to keep the movable terminal in a non-contact normal state with the fixed terminal in a normal state. And a pressure receiving pin that receives the pressure of the hydraulic circuit in a normal state and has the other end protruding from the other end of the switch housing and transmitting the pressure to the movable terminal.

When the pressure in the pressure circuit rises, the pressure receiving pin is pushed, the movable terminal moves toward the fixed terminal against the spring, and the switch is closed.

<< Problems to be Solved by the Invention >> However, in such a conventional pressure switch, the movable terminal to which the pressure receiving pin is fixed is simply resiliently urged by a spring, and maintains a non-contact normal state with the fixed terminal in a normal state. With such a configuration, the hydraulic pressure acts on the pressure receiving pin, and the operating hydraulic pressure at the time of performing the switching operation is uniquely determined.

That is, there is no difference in the operating oil pressure between the ON operation and the OFF operation of the switch.

When such a pressure switch is used, for example, in a power steering device of an automobile, the pressure switch is turned on in response to an increase in load accompanying steering operation, that is, an increase in hydraulic pressure, and the rotation of the engine driving the pump is reduced. It is necessary to raise, but in the conventional pressure switch,
Since a predetermined hysteresis cannot be obtained between the pressure at the time of the on operation and the pressure at the time of the off operation, if the oil pressure fluctuates near the pressure at the time of the switch on operation, the pressure switch repeats the on / off operation, causing a chattering phenomenon. As a result, there is a problem that a large rotation fluctuation is caused in the engine.

The present invention has been made in order to solve these problems. By setting the ON / OFF difference of the pressure switch to a predetermined value or more, even if the oil pressure fluctuates during the ON operation of the pressure switch, the chattering phenomenon of the switch is performed. It is an object of the present invention to provide a pressure switch which can perform a stable operation by preventing the pressure switch and has a small number of processing steps and a low manufacturing cost.

<< Means for Solving the Problems >> In order to achieve such an object, the present invention provides a switch housing and a fixing member including a fixed terminal fixed to one end of the switch housing, In a pressure switch including a movable terminal disposed in a non-contact normal state in a normal state and the movable terminal integrally provided with the movable terminal, and a movable member including a pressure receiving piston receiving a pressure in a hydraulic circuit, a pressure receiving surface of the pressure receiving piston is An elastic ball formed of a rubber material or the like is inserted into the hydraulic circuit facing it, and the elastic ball is elastically contacted with the inner wall of the hydraulic circuit. It is characterized in that hysteresis is provided to the member.

<< Operation >> Based on such a configuration, according to the pressure switch of the present invention, the pressure receiving pin integrated with the movable terminal of the pressure switch is:
An elastic ball formed of a rubber material or the like upstream of the pressure receiving surface of the pressure receiving pin in the hydraulic circuit is held slidably in the hydraulic circuit of the mating member so that the pressure receiving surface at the distal end receives the pressure of the hydraulic circuit. When the pressure switch is turned on and off, the elastic force of the elastic ball and the sliding resistance force act to move the movable member and the pressure-receiving piston to move the movable member. Bring.

As a result, the pressure switch performs a stable operation without causing a chattering phenomenon. Also, by adopting a configuration in which an elastic ball is inserted into the hydraulic circuit,
The number of processing steps such as machining of other parts of the pressure switch can be reduced as much as possible, and the cost can be reduced.

<< Example >> Hereinafter, an example according to the present invention will be described in detail with reference to the drawings.

FIG. 2 is a sectional view showing an oil pump of a power steering device for a vehicle to which an embodiment of the present invention is applied;
In the figure, reference numeral 1 denotes a pump casing, 2 denotes a pump shaft,
3a is a main pump including a cam ring 4a, a rotor 5a, a vane 6a, a side plate 7a, and a cover 8a, and 3b is a sub-pump including a cam ring 4b, a rotor 5b, a vane 6b, a side plate 7b, and a cover 8b. When the pump shaft 2 rotates, the vanes 6 fitted into the grooves of the rotors 5a, 5b
a, 6b jumps out in the direction of centrifugal force and slides on the inner periphery of the cam rings 4a, 4b to change the volume between the vanes 6a, 6b to perform a pump action.

Reference numeral 10 denotes a pressure switch. The pressure switch 10 is connected to the high-pressure chamber 9a of the main pump 3a or the sub-pump 3b.
The high pressure chamber 9b is connected to a hydraulic circuit (high pressure insertion hole) 11 which communicates with the high pressure chamber 9b. When the pressure switch 10 is turned on, a device for increasing the engine speed is operated.

That is, the operation of the power steering causes an increase in the load on the oil pump, the pressure in the hydraulic circuit 11 becomes equal to or higher than a predetermined value, and the rotation speed of the engine decreases. When this occurs, the system senses this and activates the device for increasing the engine speed to prevent engine stall.

FIG. 1 is an enlarged sectional view showing an embodiment of the pressure switch according to the present invention.
Denotes a switch housing made of a metal material. A male screw 14 provided on the outer periphery of the small-diameter portion 13a is screwed into a female screw 16 of a switch mounting member 15 (hereinafter, referred to as a mating member 15) so that a mounting space 17 of the mating member 15 is formed. To form a fixed member together with the mating member 15.

Also, a large diameter portion 13b at one end of the switch housing 12
Are fixed terminals 18 made of insulators 19a and 19
b is fixed through.

On the other hand, a movable terminal is slidably provided in the mounting space 17, and the movable terminal 20 is a movable member integrally fitted with the pressure receiving pin 21 by fitting the pressure receiving pin 21 as shown in the figure. And is resiliently urged by a spring 22 in a normal state, and is arranged separately from the fixed terminal 18 at a position regulated by the bottom surface of the mounting space portion 17 of the mating member 15, and is in contact with the fixed terminal 18. In a normal state, the body is grounded via the pressure receiving pin 21 to be in an energized state, and a device (not shown) for increasing the engine speed operates.

Further, in the mounting state shown in the drawing, the pressure receiving pin 21 has a pressure receiving surface 21a at the tip receiving the pressure of the hydraulic circuit 11,
It is slidably held by the hydraulic circuit 11 of the mating member 15. An elastic ball 23 formed of a rubber material or the like is inserted upstream of the pressure receiving surface 21a of the pressure receiving pin 21.
The diameter of the elastic ball 23 is selected so that the outer peripheral portion thereof elastically contacts the inner wall surface of the hydraulic circuit 11.
At the time of the ON / OFF operation of 10, the elastic ball 23 is deformed, and the resilient force and the sliding resistance force act to bring about the system to the movement with respect to the movable member including the movable terminal 20 and the pressure receiving pin 21. Has become.

In the figure, reference numeral 11a denotes a reduced diameter step portion for receiving the elastic ball 23, 24 denotes a drain hole, and 25 and 26 denote O-rings for sealing.

Next, the operation of the pressure switch 10 thus configured will be described.

First, when the pressure of the hydraulic circuit 11 is equal to or less than a predetermined value, the pressure switch 10
18 and the movable terminal 20 are kept in a non-contact state and in an off state.

Therefore, when the pressure of the hydraulic circuit 11 reaches a predetermined value, the balance between the force acting on the pressure receiving surface 21a of the pressure receiving pin 21 via the elastic force of the elastic ball 23 and the force combined with the urging force of the spring 22 is balanced. The movable terminal 20 slides upward in the state shown in the figure, and comes into contact with the fixed terminal 18 so that the pressure switch 10 turns on.

On the other hand, when the pressure of the hydraulic circuit 11 drops below a predetermined value in the ON state of the pressure switch 10, the spring 22
The force acting on the pressure receiving surface 21a of the pressure receiving pin 21 via the elastic force of the elastic ball 23 opposes the urging force of the elastic ball 23, and when the balance is lost, the movable terminal 20 slides and the pressure switch 10
Performs an off operation. In other words, the movable terminal 20 has a hysteresis when the pressure receiving pin 21 moves up and down, thereby preventing the pressure switch 10 from chattering.

Therefore, as described above, a large rotation fluctuation of the engine is prevented from occurring.

Although the embodiment of the present invention has been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment. For example, in the embodiment, a fixed terminal is shown as having one terminal. A plurality of terminals may be used as disclosed in Japanese Patent Application Laid-Open No. 58-141539.

Further, in the embodiment, the case where the present invention is used in a hydraulic circuit of a power steering system is described, but it is needless to say that the present invention is not limited to this and can be used in various pressure circuits.

<< Effects of the Invention >> As described above, the pressure switch of the present invention does not normally contact the fixed member including the switch housing and the fixed terminal fixed to one end of the switch housing, and the fixed terminal. A movable member that is provided integrally with the movable terminal and the movable terminal arranged in a state and that receives a pressure in a hydraulic circuit, and that includes a pressure-receiving piston,
Into the hydraulic circuit facing the pressure receiving surface of the pressure receiving piston, an elastic ball formed of rubber material or the like is inserted, and the elastic ball is elastically contacted with the inner wall of the hydraulic circuit. In this configuration, hysteresis is provided to the movable member during an on / off operation.

As a result, the hunting operation of the pressure switch can be prevented by the hysteresis of the relative movement between the fixed member and the movable member, and a stable operation can be performed.

In addition, by adopting a configuration in which the elastic ball is inserted into the hydraulic circuit, it is possible to reduce the machining and the like of other parts of the pressure switch as much as possible, and to reduce costs.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view showing an embodiment of a pressure switch according to the present invention, and FIG. 2 is a sectional view showing an oil pump of a power steering device for an automobile to which a practical example of the present invention is applied. 1 ... Pump casing, 10 ... Pressure switch, 11 ...
Hydraulic circuit, 12 switch housing, 18 fixed terminal, 20 movable terminal, 21 pressure receiving pin, 21a pressure receiving surface, 22 spring, 23 elastic ball.

Claims (1)

(57) [Scope of request for utility model registration] A fixed member comprising a switch housing and a fixed terminal fixed to one end of the switch housing; a movable terminal arranged in a non-contact and normal state with respect to the fixed terminal; and an integral part of the movable terminal. And a movable member comprising a pressure receiving piston receiving a pressure in the hydraulic circuit, wherein an elastic ball formed of a rubber material or the like is inserted into the hydraulic circuit facing the pressure receiving surface of the pressure receiving piston. A pressure switch, wherein the elastic ball is elastically contacted with an inner wall of the hydraulic circuit so as to cause hysteresis to the movable member at the time of on / off operation by the elastic force of the elastic ball.