JPH01273882A - Variable capacity type liquid-operated pump device - Google Patents

Abstract

PURPOSE:To decrease a discharge rate at a given running speed or more by diminishing a throttle opening undergoing power due to centrifugal force, which is caused by a rotational drive of a drive shaft. CONSTITUTION:Action force caused by centrifugal force caused by rotational drive of a drive shaft 5 is applied to the valve body 19 of a variable throttle valve 17, until the rotational speed of the drive shaft 5 reaches a preset rotational speed, however discharge rate is increased proportionally to an increase in the rotational speed because of unchanged throttle opening. After the rotational speed of the drive shaft 5 reaches to a preset rotational speed, the variable throttle valve 17 diminishes its opening with the valve body 19 moved by action force due to centrifugal force which is caused by the rotational drive of the drive shaft 5, so as to increase the difference between the front and the rear pressures of the variable throttle valve 17 due to its diminished opening to move a operative piston 12 for displacing a discharge rate changing member 10 in a direction for decreasing the discharge rate.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is directed to a power steering device that is rotationally driven by a variable speed drive source (for example, an engine of a vehicle, a ship, etc.) and supplies discharged liquid to a power steering device as a load. The present invention relates to a variable displacement hydraulic pump device.

[Conventional technology]

Conventionally, when a variable displacement hydraulic pump device as shown in Japanese Patent Publication No. 41-15377 is rotationally driven by a drive source with a variable rotation speed, the discharge liquid of the variable displacement hydraulic pump is disposed in a discharge flow path. The throttle is controlled by a fixed throttle valve and supplied to the power steering device. In the pressure compensation valve, the acting force based on the pressure difference between the front and rear of the fixed throttle valve and the elastic force of the elastic member act oppositely on the valve body, and the acting force based on the front and rear pressure difference of the fixed throttle valve is greater than the elastic force of the elastic member. When it is small, the valve body communicates with the low pressure side an action chamber formed on the back side of the operating piston that displaces the swash plate as the discharge amount changing member. The swash plate is located at the maximum inclination angle at which the maximum discharge amount can be obtained, and the discharge amount of the variable displacement wave pressure pump increases in proportion to the increase in the rotational speed, as shown in FIG. After the rotational speed of the drive shaft of the variable displacement wave pressure pump increases to the constant rotational speed N1 shown in Fig. 5, the pressure difference generated before and after the fixed throttle valve increases due to the increase in the discharge amount. When the acting force based on becomes larger than the elastic force of the elastic member, the pressure compensating valve is operated so that the valve body introduces the pressure liquid into the operating chamber of the operating piston,
The operating piston moves to reduce the inclination angle of the swash plate by the action force based on the pressure liquid introduced into the action chamber, and the discharge amount per revolution of the variable displacement wave pressure pump decreases, and the number of revolutions increases thereafter. Since the discharge amount per rotation decreases in accordance with the rotation speed, the discharge amount is kept constant regardless of the increase in the rotation speed at a rotation speed greater than a certain rotation speed N1 as shown in FIG.

[Problem that the invention seeks to solve]

However, in a power steering device, it is desirable to reduce the discharge amount as the rotation speed increases so that the steering operation cannot be easily performed when the rotation speed of the drive shaft of the variable displacement wave pressure pump exceeds a certain rotation speed. In conventional variable displacement hydraulic pump devices, the discharge amount is constant above a certain rotation speed, so there was a problem that such an effect could not be expected at all.The present invention solves this problem, and the drive The present invention provides a variable displacement wave pressure pump device that can reduce the discharge amount as the rotational speed increases above a certain rotational speed of the shaft.

[Means for solving problems]

For this reason, the present invention provides a rotating body that rotates together with a drive shaft rotationally driven by an external drive source to suck liquid from a suction channel and discharge it to a discharge channel, and introduces a pressurized liquid into an action chamber. A variable displacement wave pressure pump that changes the amount of liquid discharged by displacing a discharge amount changing member using an operation piston that moves by directing the liquid in the action chamber to the low pressure side, and a discharge flow path for the discharged liquid. A force based on the pressure difference and an elastic force of the elastic member act oppositely on the valve body to maintain a constant pressure difference between the variable throttle valve installed and the variable throttle valve installed in the discharge flow path. Equipped with a pressure compensating valve that introduces pressure liquid into the working chamber of the operating piston of the υ variable displacement wave pressure pump or leads out the liquid in the working chamber to the low pressure side by moving the valve body to its equilibrium position. However, the variable throttle valve is installed so that the valve body receives the centrifugal force generated by the rotation of the drive shaft, and the throttle opening does not change until the drive shaft reaches a certain rotation speed. [Function] In the structure of the present invention, the valve body is provided so as to be movable so as to reduce the throttle opening according to the increase in the rotation speed after the rotation speed has increased to a certain level. Until the rotational speed of the variable throttle valve increases to a certain rotational speed, the valve body of the variable throttle valve receives the acting force due to the centrifugal force generated by the rotation of the drive shaft, but the throttle opening does not change and the rotational speed increases. The discharge amount increases in proportion to. After the rotation speed of the drive shaft increases to a certain rotation speed, the valve body of the variable throttle valve moves due to the centrifugal force generated by the rotation of the drive shaft, reducing the throttle opening. Due to the decrease, the pressure difference between the front and rear of the variable throttle valve increases, and the pressure compensation valve moves the valve body to a position where the acting force based on the pressure difference between the front and rear of the variable throttle valve whose throttle opening has decreased and the elastic force of the elastic member are balanced. Pressure liquid is introduced into the action chamber of the operating piston, and the operating piston moves to displace the discharge amount changing member in the direction of decreasing the discharge amount, so that the pressure difference between the front and rear of the variable throttle valve whose throttle opening degree has been reduced is kept constant. Reduce the discharge volume of the variable displacement wave pressure pump. Thereafter, as the rotation speed of the drive shaft increases, the acting force due to centrifugal force increases sequentially, and the variable throttle valve gradually decreases the throttle opening. Therefore, when the rotation speed of the drive shaft exceeds a certain rotation speed, 0 [Example] An example of the present invention will be described below with reference to the drawings.

In Fig. 1, reference numeral 1 denotes a swash plate type variable displacement piston pump as a variable displacement wave pressure pump. 4. Reference numeral 5 denotes a drive shaft rotatably supported inside the pump body 4, with one end protruding from the pump body 4 so as to be coupled to a variable speed drive source (not shown). Reference numeral 6 denotes a cylinder block as a rotary body, which is supported by the drive shaft 5 via a spline portion 7 formed in the middle of the drive shaft 5 so as to rotate together with the drive shaft 5. A large number of pistons 18 are installed in the cylinder block 6 so as to be able to reciprocate with a predetermined stroke, and a shoe 9 is attached to the tip of each piston 8, and a swash plate as a discharge amount changing member is attached to the tip of each piston 8. Connected to 10. The swash plate 10 is capable of swinging within a certain range of inclination angle, and a spring 11 as an elastic member is interposed between the back surface of the side where the shoe 9 contacts and the inner surface of the housing body 2. The angle of inclination of the swash plate 10 is always maximized. Therefore, when the drive shaft 5 is rotationally driven to rotate the cylinder block 6 in this state, the piston 8 reciprocates and the maximum discharge amount is obtained. 1
Reference numeral 2 denotes an operating piston movably inserted into a guide 13 protruding from the lid member 3 into the housing body 2, and has its tip end in contact with the swash plate 10, and has an action chamber 14 formed on its back side. Reference numeral 015 is a liquid intake flow path, and 16 is a liquid discharge flow path. Reference numeral 17 denotes a variable throttle valve that throttles and controls the discharge liquid discharged into the discharge flow path 16;
A valve body 18 is fixed to the lid member 3 of the valve body 18, and a fitting hole 20 into which the valve body 19 is slidably inserted is bored in the valve body 18. The discharge flow path 16 has
A discharge flow path 21 as the front side of the variable throttle υ valve 17 communicating with the
A discharge flow path 22 on the rear side of the variable throttle valve 17 is formed as an opening. The valve body 19 has a throttle υ that communicates with the discharge passage 21.
The hole 23 and a through hole 24 communicating with the discharge flow path 22 are provided in communication with each other through an internal axial hollow hole 25, and the valve body 19 is supported by the elastic force of springs 26 and 27 as elastic members acting oppositely on both ends. By moving to a position in equilibrium with the acting force which will be described in detail later, the opening degree of the throttle hole 23 is increased or decreased by the land portion 20A of the insertion hole 20, making the throttle opening variable, and the illustrated state is a spring 26 degree. The elastic force of 27 maximizes the υ throttle opening.

28 is an adjustment screw for adjusting the elastic force of the springs 26 and 27. Reference numeral 29 denotes a pressure compensation valve that controls the discharge amount to increase or decrease so as to keep the pressure difference between the front and rear of the variable throttle valve 170 constant, and is located above the lid member 3 of the variable displacement hydraulic pump 1 and the valve body 18 of the variable throttle valve 17 A valve body 30 is arranged, and inside the valve body 30 there are a fitting hole 32 into which the valve body 31 is slidably inserted, and a spring aa% hole 34 as an elastic member which applies an elastic force to the valve body 31. The fitting hole 32 has a flow path 35 branched from the discharge flow path 16 on the front side of the variable throttle valve 17 with an interval in the axial direction, and an operation pipe 120 and a pressure, which will be described later, in the action chamber 14. A flow path 36 communicating through the control valve and a flow path 37 communicating with the low pressure side are opened, and a flow path 38 branched from the discharge flow path 22 on the rear side of the variable throttle valve 17 is opened in the housing hole 34. are doing. The valve body 31 has an acting force based on the pressure difference between the front side pressure of the variable throttle valve 17 that acts through the flow path 35 and the rear side pressure of the variable throttle valve 17 that acts through the flow path 38 and acts oppositely on both ends. By moving the spring 330 to an equilibrium position with the elastic force, the land portion 3
1A, the flow path 36 is switched and communicated with the flow path 35 and the flow path 37 to introduce pressure liquid into the action chamber 14 of the operation piston 12 or to lead out the liquid in the action chamber 14 to the low pressure side. ing.

Reference numeral 39 denotes a pressure control valve for setting the maximum pressure of discharged liquid, and a fitting hole 41 into which a valve body 40 is slidably inserted is bored in a valve body 30 provided with a pressure compensating valve 29. 41 is a valve body in which a flow path 35 branching from the discharge flow path 16 with an interval in the axial direction, a flow path 42 communicating with the action chamber 14 of the operation piston 13, and the aforementioned flow path 36 are opened. 40 is the flow path 35
When the pressure of the discharge passage 16 acting on one end becomes equal to or higher than the set pressure based on the elastic force of the spring 43 acting as an elastic member acting on the other end, the land portion 40A moves the passage 42 to the passage 3.
044 is in switching communication with the variable throttle valve 1 to introduce pressure liquid into the operation chamber 14 of the operating valve 120.
It is an operating mechanism that acts on the valve body 19 of No. 7 against the elastic force of the spring 26, 27, and is provided between the other end of the drive shaft 5 and the variable throttle valve 17, and is shown in FIGS. 2 and 3. As shown in detail, the other end of the drive shaft 5 is divided into four equal parts in the circumferential direction to form four notch grooves 45 extending in the axial direction.
A blade member 46 is fitted into the blade member 46 so as to be slidable in the axial direction and the radial direction. A conical member 48 having a conical hole 47 that is fixedly attached to the lid member 3 and whose diameter gradually increases toward the variable throttle valve 17 side is disposed on the outer peripheral part of the blade member 46, and the outer peripheral surface of each blade member 46 is formed into a conical shape. It is formed into a tapered circular arc surface that gradually expands toward the variable throttle valve 17 side so as to correspond to the inner lateral surface of the hole gap 47. 49 is an annular transmission member fitted to the other end of the drive shaft 5 and provided in contact with one side of each blade member 48; 50 is a variable throttle valve 1;
A piston 052 is slidably inserted into the end of the valve body 18 of the variable throttle valve 17, and is in contact with the valve body 19 of the variable throttle valve 17, and is provided non-rotatably by the pin 51.
A bearing provided between the transmission member 49 and the piston 50
Acting force in the axial direction is transmitted from the piston 50 to the piston 50 without transmitting rotational force. Each blade member 46 rotates together with the drive shaft 5 and is pressed against the conical member 48 by the centrifugal force generated by the rotation of the drive shaft 50.
A reaction force of the pressed force acts on each blade member 46, and a horizontal component of the reaction force causes each blade member 46 to slide in the right direction in FIG. 2 along the inner peripheral surface of the conical hole 47. This acting force acts on the valve body 19 of the variable throttle valve 17 via the transmission member 49, the bearing 52, and the piston 50.

Next, the operation of this configuration will be explained.

In the illustrated state, the variable throttle valve 17 has a valve body 19 with a spring 26.2.
The pressure compensating valve 29 is pushed by the elastic force of the valve body 3 and is located at the left end, and the throttle opening of the throttle hole 23 is maximized.
1 is pressed by the elastic force of the spring 33 and is located at the left end, communicating the flow path 36 with the flow path 37, and the pressure control valve 39 has a valve body 40 pressed by the elastic force of the spring 43 and located at the left end. The flow path 42 is connected to the flow path 36, and the action chamber 14 of the operating piston is connected to the low pressure side via the flow path 42, 36, 37. In this state, when the drive shaft 5 is rotated by a drive source with a variable speed, the maximum discharge amount per revolution is obtained, and as shown in Fig. 4, it is proportional to the increase in the rotation speed. As a result, the discharge amount increases. Then, as the rotational speed increases, the centrifugal force generated by the rotational drive of the drive shaft 5 becomes larger than the elastic force of the spring 26. The throttle valve 17 moves to the right from the illustrated state to a position where the acting force and elastic force of the valve body 19 are in equilibrium, thereby reducing the throttle opening. Variable throttle valve 1
7, the pressure difference between the pressure in the discharge passage 16.21 on the front side of the variable throttle valve 17 and the pressure in the discharge passage 22 on the rear side of the variable throttle valve 17 increases, and the pressure compensation valve 29 increases. The acting force based on the pressure difference between the front and back of the variable throttle valve 17 acting oppositely on the valve body 31 becomes greater than the elastic force of the spring 330, and the pressure compensating valve 29 moves the valve body 31 to a position where the acting force based on the pressure difference and the elastic force are in equilibrium. The flow path 36 is switched to the flow path 35 by sliding to the right from the state, and a part of the discharge liquid flowing through the discharge flow path 16 flows through the flow paths 35, 36, 42 as pressure liquid to the action chamber 14. The operation piston 12 slides to the left from the illustrated state against the elastic force of the spring 11 due to the action force based on the pressure liquid introduced into the action chamber 14, thereby reducing the inclination angle of the swash plate 10 and discharging. The discharge amount discharged into the flow path 16 is decreased so as to keep the pressure difference between the front and rear of the variable throttle valve 17 constant ◇Then, the pressure compensation valve 29 decreases the discharge amount of the flow path 36 in order to keep the pressure difference between the front and rear of the variable throttle valve 17 constant. Switching and communicating between the flow path 35 and the flow path 37 is repeated to introduce pressure liquid into the action chamber 14 or lead out the liquid in the action chamber 14 to the low pressure side. From then on,
As the rotation speed increases, the centrifugal force increases and the variable throttle valve 17
The force acting on the valve body 19 increases, and the variable throttle valve 17 sequentially slides to the right to sequentially decrease the throttle opening. The pressure compensating valve 29 introduces pressure liquid into the action chamber 14 and directs the liquid in the action chamber 14 to the low pressure side so that the pressure difference between the front and rear of the variable throttle valve 170, whose throttle opening gradually decreases, is kept constant, and the swash plate The inclination angle of 10 is sequentially decreased, and the discharge amount is gradually decreased as the rotation speed increases when the rotation speed is higher than a certain rotation speed N1 as shown in FIG. From this state, if the rotation speed is reduced,
Up to the constant rotational speed N1 in FIG. 4, the throttle opening of the variable throttle valve 17 increases sequentially as the rotational speed decreases, and the discharge amount is gradually increased. Throttle valve 1
The aperture opening of 7 becomes the maximum and the discharge amount becomes the maximum, and from then on,
The discharge amount decreases in proportion to the decrease in the number of rotations, and becomes zero when it stops. Note that the pressure control valve 39 closes the discharge flow path 1 at a rotation speed equal to or higher than a certain rotation speed N1 in FIG.
When the discharge pressure of 6 exceeds the set pressure based on the elastic force of the spring 43, the valve body 40 slides to the right from the state shown in the figure, switches the flow path 42 to the flow path 35, and connects the flow path 42 to the flow path 35, thereby opening the working chamber 14. By introducing pressure liquid into the discharge flow path 16 and reducing the discharge amount.
Maintain the discharge pressure below the set pressure.

With this operation, after the rotation speed of the drive shaft 5 increases to a constant rotation speed N1 that is greater than the acting force due to the centrifugal force generated by the rotation of the drive shaft 50 and the elastic force of the springs 26 and 27, the variable throttle valve 17 The valve body 19 moves due to the acting force of the centrifugal force that increases as the rotation speed increases, and the throttle opening degree decreases sequentially, and pressure is applied to keep the pressure difference between the front and rear of the variable throttle valve 17, which gradually decreases the throttle opening degree, constant. Since the compensation valve 29 operates to reduce the discharge amount, the discharge amount can be reduced as the rotation speed increases above a certain rotation speed N1.

In addition, the variable throttle valve 17 receives the acting force of the centrifugal force generated by the rotational drive of the drive shaft 5 on the valve body 19 to reduce the throttle opening. It can be operated by rotational drive, and does not require any electrical work such as electrical wiring, making it easy to handle.

In one embodiment, a swash plate variable displacement piston pump was used as the variable displacement wave pressure pump, but a variable displacement vane pump may also be used. [Effects of the Invention] As described above, the present invention The system is equipped with a rotating body that rotates together with a drive shaft that is rotatably driven by an external drive source to suck liquid from the suction channel and discharge it to the discharge channel, and introduces pressurized liquid into the working chamber or drains the liquid in the working chamber. A variable displacement wave pressure pump that changes the amount of liquid discharged by displacing a discharge amount changing member using an operating piston that moves by sipping and leading out to the low pressure side, and a variable throttle disposed in the discharge flow path of the discharged liquid. In order to keep the pressure difference between the front and rear of the valve and the variable throttle valve disposed in the discharge flow path constant, the acting force based on the pressure difference and the elastic force of the elastic member act oppositely on the valve body, and the valve returns to its equilibrium position. It is equipped with a pressure compensating valve that introduces pressure liquid into the action chamber of the operation piston of the hydraulic pump and directs the liquid in the action chamber to the low pressure side by moving the body, and the variable throttle valve is connected to the drive shaft. The valve body is designed so that the centrifugal force generated by the rotational drive of the valve body is received by the valve body, and the throttle opening does not change until the drive shaft reaches a certain rotational speed, and after the rotational speed reaches a certain level. By providing a movable valve body that reduces the throttle opening as the rotational speed increases, the discharge amount can be reduced as the rotational speed increases when the rotational speed of the drive shaft exceeds a certain rotational speed. can.

In addition, the variable throttle valve receives the centrifugal force generated by the rotation of the drive shaft on the valve body to reduce the throttle opening, so the drive shaft of the variable displacement wave pressure pump is rotated. It has the effect of being easy to handle without requiring any electrical work such as electrical wiring.

[Brief explanation of the drawing]

1 to 4 show an embodiment of the present invention, in which FIG. 1 is a vertical sectional view of a variable displacement wave pressure pump device, and FIG.
The figure is a partially enlarged sectional view of the main part, and Figure 3 is line 1-1 in Figure 2.
4 is a pump characteristic diagram, and FIG. 5 is a conventional pump characteristic diagram.
. 12... Operation piston, 14... Action chamber, 15...
Suction channel, 16, 21.22...Discharge channel, 17...
- Variable throttle valve, 29...pressure compensation valve.

Claims (1)

[Claims] A rotating body is provided so that it rotates together with the drive shaft that is rotationally driven by an external drive source, sucks liquid from the suction channel and discharges it to the discharge channel, and introduces pressurized liquid into the working chamber or lowers the liquid in the working chamber. A variable displacement hydraulic pump that changes the amount of liquid discharged by displacing a discharge amount changing member with an operating piston that moves by guiding it out to the side, and a variable throttle valve that is disposed in the discharge flow path of the discharged liquid. In order to keep the pressure difference between the front and rear of the variable throttle valve disposed in the discharge flow path constant, the acting force based on the pressure difference and the elastic force of the elastic member act oppositely on the valve body, and the valve body returns to its equilibrium position. The variable throttle valve is equipped with a pressure compensation valve that introduces pressure liquid into the action chamber of the operating piston of the variable displacement hydraulic pump and directs the liquid in the action chamber to the low pressure side by movement, and the variable throttle valve is driven by the rotation of the drive shaft. The valve body is designed to receive the acting force of centrifugal force generated by A variable displacement hydraulic pump device characterized by having a movable valve body so as to reduce the opening degree of the throttle according to the rise.