JPS63219476A - Flow rate control device for power steering hydraulic pump - Google Patents

Abstract

PURPOSE:To increase the reflux which passes through a flow control valve and lower the power of the hydraulic pump in the title by installing an orifice which reduces oil pressure in an oil chamber which contains a spring which energizes the spool valve of the flow control value onto the close side when the number of revolution of the hydraulic pump exceeds a certain number. CONSTITUTION:In the hydraulic pump P shown in the title, an oil supplying line 21 which leads to a pump outlet 10 is opened in a side block 5 which divides and forms a pump chamber 2 in which a pair of gears 3 which engage each other are installed and this oil supplying line 21 is connected to a power steering device 23. A metering orifice 25 is installed in the way of the oil supplying line 21 and a flow control valve V which is controlled in proportion to the difference between the pressures before and behind the metering orifice 25 is installed between the upperstream side of the oil supplying line 21 and a pump inlet 9. In this case, an orifice 45 which opens to the sliding hold 26 of the flow control valve V is formed in a connecting line 33 which connects a damper orifice 32 on the downstream side of the metering orifice 25 to an oil chamber 29 and it is made possible that the oil chamber 29 and the inlet 9 are connected through when the number of revolution of the bydraulic pump exceeds a certain number.

Description

Detailed Description of the Invention A0 Object of the Invention (1) Industrial Field of Application The present invention relates to a metering orifice provided in the middle of an oil supply path connected to a discharge port of a hydraulic pump; An oil supply passage upstream of the metering orifice is communicated with the oil chamber in order to bias the spool valve element toward the opening side, and a second oil chamber facing the other end of the spool valve element is configured to bias the spool valve element toward the closing side. Seisube (a flow control valve that communicates with the oil supply passage downstream of the metering orifice and houses a spring, and is interposed between the oil supply passage upstream of the metering orifice and the suction port of the hydraulic pump) The present invention relates to a hydraulic pump for a power steering device, and particularly relates to a flow rate control device for a hydraulic pump for a power steering device that is sensitive to rotation speed and reduces the flow rate in a high rotation range.

(2) Prior Art Conventionally, in such devices, the opening area of the metering orifice is made small in a high rotation range to restrict the flow rate.

(3) Problems to be Solved by the Invention However, in the conventional device described above, as the opening area of the metering orifice becomes smaller, the pressure loss increases, and therefore the power loss of the hydraulic pump increases.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a flow rate control device for a hydraulic pump for a power steering device that reduces power loss of the hydraulic pump.

B0 Structure of the Invention (Means for Solving 11 Problems) According to the present invention, when the operating amount of the spool valve body in the valve opening direction exceeds a set value, the second oil chamber and the suction port of the hydraulic pump An orifice is provided between the two.

(2) Effect According to the above configuration, when the rotation speed of the hydraulic pump increases and the differential pressure across the metering orifice becomes large, and the flow control valve opens to the desired opening, the second oil chamber is opened through the orifice. Since the oil pressure in the second oil chamber is communicated with the suction port of the hydraulic pump, the oil pressure in the second oil chamber decreases, the opening degree of the flow rate control valve further increases, and the amount of oil supplied to the power steering device decreases.

(3) Embodiment Below, an embodiment of the present invention will be described with reference to the drawings. First, in FIG. 1, a hydraulic pump P is interlocked and connected to the engine, and the hydraulic oil pumped from the oil tank T is It is supplied from the hydraulic pump P to the rotation speed sensitive power steering device 23.

The hydraulic pump P is comprised of a pair of gears 3 that mesh with each other in a pump chamber 2 formed in a box 1, and the box 1 has side blocks 5 and 6 that can be attached and removed on both sides of a central block 4. It is composed of a combination of .

The central block 4 has a hole 7 that is closed at both ends by side blocks 5 and 6. By sliding a plunger 8 into the hole 7, the pump is inserted between one end surface of the side block 5 and the plunger 8. Both gears 3 that define the chamber 2 are in sliding contact with the inner surface of the pump chamber 2, and an inlet opening is provided on the inner surface of the pump chamber 2 corresponding to the portion where the two gears 3 release their mutual meshing state. 9 and a discharge port 10 that opens into the inner surface of the pump chamber 2 corresponding to the portion where both gears 3 start meshing with each other are provided in the central block 4.

Both end faces in the axial direction of both gears 3 are in sliding contact with the side block 5 and one end face of the plunger 8, and a hydraulic chamber 1 defined between the other end face of the plunger 8 and the side block 6
1 is communicated with the discharge port 10 via a communication passage 12 formed in the central block 4.

Therefore, the discharge pressure of the hydraulic pump P is introduced into the hydraulic chamber 11, and the plunger 8 is pressed against both gears 3 according to the hydraulic pressure of the hydraulic chamber 11. Due to the action of this plunger 8,
The end faces of both gears 3 and the clearance between the side block 5 and plunger 8 are adjusted appropriately.

Both gears 3 are integrally provided on a pair of rotating shafts 13 that are parallel to each other, one end of each rotating shaft 13 is supported by the plunger 8 via a cylindrical bearing member 14, and each rotating shaft 13 is The other end is attached to the side block 5 with a cylindrical bearing member 1.
5, respectively. Also, one rotating shaft 13
One end of the seal member 16 is connected to the side block 6.
An endless belt 20 is wound around a pulley 17 fixed to the protruding end of the rotating shaft 13 and a pulley 19 provided to the crankshaft 18 of the engine E. As a result, the hydraulic pump P is interlocked and connected to the engine E.

An oil supply passage 21 communicating with the discharge port 10 of the hydraulic pump P is bored in the side block 5, and a pipe line 22 connected to the oil supply passage 21 is connected to a power steering device 23. Further, the power steering device 23 and the oil tank T are connected by a conduit 24.

A metering orifice 25 is provided in the middle of the oil supply path 21 within the side block 5. Between the oil supply path 21 on the upstream side of this metering orifice 25 and the suction port 9 of the hydraulic pump P, a flow rate control is performed to increase the opening degree in accordance with the increase in the differential pressure across the metering orifice 25. A valve V is interposed.

The flow rate control valve V is constructed by sliding a spool valve body 27 into a sliding hole 26 bored in the central block 4 such that both ends are closed by side blocks 5.6, and the sliding hole 26 is connected to a hydraulic pump P. It is provided in the box 1 parallel to the rotation axis 13 of. A first oil chamber 28 is defined between one end of the spool valve body 27 that slides into the sliding hole 26 and the side block 5, and a second oil chamber 28 is defined between the other end of the spool valve body 27 and the side block 6.
An oil chamber 29 is defined. Moreover, the central block 4 is provided with a return passage 30 that communicates with the suction port 9 of the hydraulic pump P and opens on the inner surface of the sliding hole 26, and the spool valve body 27 is connected to the second oil chamber 28 from the first oil chamber 28. The degree of opening of the reflux path 30 increases as it moves toward the chamber 29 side.

The first oil chamber 28 and the oil supply path 21 on the upstream side of the metering orifice 25 communicate with each other through a communication hole 31.
Hydraulic pressure from the oil supply path 21 upstream of the metering orifice 25 is introduced into the oil chamber 28 in order to urge the spool valve body 27 toward its opening side. Moreover, the spool valve body 27 is connected to the second oil chamber 2.
9 side to open the valve, the first oil chamber 28 communicates with the return passage 30, and an amount of hydraulic oil corresponding to the opening degree of the return passage 30 is supplied to the oil supply upstream of the metering orifice 25. The oil is refluxed from the passage 21 to the suction port 9 via the first oil chamber 28 and the reflux passage 3°.

A damper orifice 32 communicating with the oil supply passage 21 is bored in the side block 5 on the downstream side of the metering orifice 25, and a communication passage 33 connecting the damper orifice 32 and the second oil chamber 29 is bored in the center block 4. be done. Therefore, the second oil chamber 29 has an oil supply path 2 downstream of the metering orifice 25 in order to bias the spool valve body 27 toward the closing side.
1 hydraulic pressure is introduced. Moreover, there is a spring 3 in the second oil chamber 29.
4 is accommodated, and the spool valve body 27 is biased in the closing direction by the spring force of the spring 34 and the hydraulic pressure generated by the oil pressure of the second oil chamber 29. The damper orifice 32 is provided to prevent oil pressure fluctuations in the oil supply path 21 on the downstream side of the metering orifice 25 from directly acting on the second oil chamber 29, thereby reducing the axial vibration of the spool valve body 27. can be suppressed.

A relief valve 35 is attached to the spool valve body 27 for relieving the hydraulic pressure in the second oil chamber 29, that is, the hydraulic pressure downstream of the metering orifice 25, to the suction port 9. A valve seat member 37 having a valve hole 36 communicating with the second oil chamber 29 is coaxially screwed onto the end of the spool valve body 27 on the second oil chamber 29 side. A valve chamber 38 is defined between the valve chamber 27 and the valve chamber 38 . The relief valve 35 includes a valve seat 39 provided in the valve seat member 37 surrounding the opening end of the valve hole 36 to the valve chamber 38, and a spherical valve seat 39 arranged in the valve chamber 38 so as to be seatable on the valve seat 39. It consists of a valve body 40 and a valve spring 41 housed within the valve chamber 38 to urge the valve body 40 toward the valve seat 39. The valve body 40 is held by a holder 42, and the valve spring 41 is interposed between the spool valve body 27 and the holder 42.

An annular groove 43 is provided on the outer surface of the spool valve body 27 and is in continuous communication with the reflux path 30.
The spool valve body 27 communicates with the spool valve body 27 through a passage 44 formed in the spool valve body 27. Therefore, when the relief valve 35 is operated to open, the second oil chamber 29 includes the valve hole 36, the valve chamber 38, the passage 44
, communicates with the suction port 9 via the annular groove 43 and the reflux path 30.

The central block 4 is provided with an orifice 45 that communicates with the communication passage 33 and opens on the inner surface of the sliding hole 26 . On the other hand, on the outer surface of the spool valve body 27, when the spool valve body 27 is displaced from the first oil chamber 28 to the second oil chamber 29 side and opens the return passage 30 by a certain opening degree, the orifice 45 is formed. An annular groove 46 communicating with the valve chamber 38 is provided in the passage 4 provided in the spool valve body 27.
It communicates via 7. Therefore, when the orifice 45 communicates with the annular groove 46, the communication passage 33, that is, the second oil chamber 29, connects the orifice 45, the annular groove 46, and the passage 47.
, the valve chamber 38, the passage 44, the annular groove 43, and the reflux passage 30, which communicate with the suction port 9 of the hydraulic pump P.

A suction passage 48 communicating with the suction port 9 of the hydraulic pump P is bored in the central block 4 and the side blocks 5.
This suction path 48 is connected to the oil tank T via a pipe 49.

Next, to explain the operation of this embodiment, the engine E
Hydraulic pump P also starts operating in response to the start of
As shown in the figure, in the low rotation range where the rotation speed N0 is not grooved, the flow control valve V is in a closed state, and the amount of hydraulic fluid supplied to the power steering device 23 through the metering orifice 25 is increases proportionally as .

When the rotational speed of the hydraulic pump P increases and exceeds the rotational speed N0, the flow control valve V is opened so that the differential pressure before and after the metering orifice 25 is constant, and the oil supply upstream of the metering orifice 25 is started. Some of the hydraulic oil is transferred from path 21 to the hydraulic pump P.
It is refluxed to the inlet 9 of the Therefore, the amount of hydraulic oil supplied to the power steering device 23 remains constant.

When the rotational speed further increases to N, or more, the spool valve body 27 of the flow control valve V operates toward the opening side by a certain amount or more, and the orifice 45 communicates with the annular groove 46, thereby opening the communication passage 33, that is, The second oil chamber 29 communicates with the suction port 9 via the orifice 45. Therefore, the oil pressure in the second oil chamber 29 decreases rapidly, and the spool valve body 27 further moves toward the opening side. Therefore, the recirculation passage 30 becomes fully open, the flow rate of hydraulic oil recirculated to the suction port 9 of the hydraulic pump P increases, and the amount of hydraulic oil supplied to the power steering device 23 decreases.

The power characteristics of the hydraulic pump P due to such operation are as shown in Fig. 3, and the conventional type in which the opening area of the metering orifice 25 is made small, increases as the rotation speed increases as shown by the chain line. On the other hand, in the case where the second oil chamber 29 and the suction port 9 are communicated through the orifice 45 at the rotation speed N5 or more, the power decreases once at the rotation speed N1 and then increases. , it is possible to reduce power loss as a whole.

The relief valve 35 opens when the hydraulic pressure downstream of the metering orifice 25 becomes higher than a set value, and surplus hydraulic pressure is returned to the suction port 9 of the hydraulic pump P.

C0 Effects of the invention As described above, according to the invention, an orifice connecting the second oil chamber and the suction port of the hydraulic pump is provided in response to the operating amount of the spool valve body in the valve opening direction exceeding a set value. Therefore, when the rotational speed of the hydraulic pump exceeds a certain value and the opening degree of the flow control valve exceeds a certain value, the hydraulic pressure in the second oil chamber is reduced, and the opening degree of the flow control valve is increased to return the oil pressure. increase the flow rate,
The amount of hydraulic oil supplied can be reduced, and power loss can be reduced compared to the conventional system in which the opening area of the metering orifice is made smaller.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a longitudinal sectional view, FIG. 2 is a control flow characteristic diagram, and FIG. 3 is a power characteristic diagram.

Claims (1)

[Claims] A metering orifice is provided in the middle of the oil supply path that connects to the discharge port of the hydraulic pump; and a first oil chamber facing one end of the spool valve body is provided with oil supply upstream of the metering orifice in order to bias the spool valve body toward the opening side. The second oil chamber facing the other end of the spool valve body communicates with an oil supply passage downstream of the metering orifice and houses a spring in order to urge the spool valve body toward the closing side. , a flow control valve for a hydraulic pump for a power steering device, which comprises: a flow control valve interposed between an oil supply path upstream of a metering orifice and an intake port of the hydraulic pump; 1. A flow rate control device for a hydraulic pump for a power steering device, characterized in that an orifice is provided that connects a second oil chamber and a suction port of the hydraulic pump in response to an operating amount exceeding a set value.