JPH10230860A - Flow controller for power steering - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce cost by simplifying structures of a throttle passage and a pressure fluid supplying port part and miniaturizing the whole flow controller, in a flow controller for a pump revolution sensing-type power steering of a vehicle. SOLUTION: In a flow controller for a power steering, a plurality of throttle passages are composed of a fixed throttle passage 9, and a variable throttle passage 10 arranged in series with the fixed throttle passage 9, the fixed throttle passage 9 and the variable throttle passage 10 are formed of a communication passage 7 for communicating a spool housing hole 3 for a flow controlling spool valve with a pressure oil fluid supplying chamber 6 to a power steering device, and a pin member 8 projectingly provided on the end of a spool 2, inserted through the communication passage 7, and provided with a taper part in the intermediate part. The pressure oil fluid supplying chamber 6 has the diameter larger than the spool housing hole 3 and provided on the side wall of a caring 1 for a pump 14, and a back pressure oil passage 19 for linking the pressure oil fluid supplying chamber 6 and a second valve chamber 12 for the flow controlling spool valve is formed on the casing 1 of the pump 14 along the spool housing hole 3 so as to be opened to the pressure oil fluid supplying chamber 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power steering apparatus in which a pressure fluid discharged from a pump whose pump discharge flow rate increases in response to an increase in the pump speed is supplied to a power steering device through a plurality of throttle passages in a supply passage. The present invention relates to a power steering flow control device for returning excess pressure fluid to a suction side of the pump via a first valve chamber of a flow adjustment spool valve for adjusting an opening degree of a return passage. In the rotation range, the supply flow rate to the power steering device increases in response to the increase in the pump rotation speed, and in the medium rotation speed range of the pump rotation speed, the supply flow rate to the power steering device increases regardless of the increase in the pump rotation speed. It is kept substantially constant, and in the high-speed rotation range of the pump rotation speed, the supply flow rate to the power steering device gradually decreases in response to the increase in the pump rotation speed, and then the rotation speed in the middle speed range is reduced. It is maintained at a substantially constant flow rate lower than the supply flow rate, and in the high-speed rotation range of the pump rotation speed, the pump discharge pressure increases slowly without being affected by the increase in the pump rotation speed, and the pump driving torque increases. The present invention relates to a flow rate control device for a power steering of a vehicle, which is controlled by a pump rotation speed.

[0002]

2. Description of the Related Art FIGS. 8 and 9 show a conventional flow rate control device for a pump rotation speed type, that is, an engine rotation speed type power steering (see Japanese Utility Model Publication No. 7-10071). The casing 01 of the conventional flow rate control device shown in these figures is provided with a spool accommodation hole 03 in which a flow adjustment spool 02 is slidably fitted. The spool accommodation hole 03 is provided in the spool accommodation hole 03 by a predetermined distance in the axial direction. A supply passage 04 and a return passage 05 which are open apart are formed, and a union 016 for supplying a pressure fluid to a power steering device (not shown) is integrally fitted to the casing 01 at the right end of the spool housing hole 03, The tip of the union 016
A cylindrical member 016b for forming a throttle passage is fitted integrally and concentrically with the spool accommodating hole 03 to the pressure fluid supply port 06 of the flow rate adjusting spool 02. A pin member (needle pin) 08 penetrates a communication path 07 formed by the inner peripheral surface of the member 016b, and is protruded therefrom.
Consists of three parts: a small diameter portion 08a at the base end, a large diameter portion 08b at the front end, and an intermediate tapered portion 08c connecting them. Due to the minute gap between the inner peripheral surface of the communication passage 07 and the fixed throttle passage 09
Also, the variable throttle passage 010 is formed by the intermediate tapered portion 08c and the opening 07a of the communication passage 07 on the side of the pressure fluid supply port 06.
Are formed respectively. The variable throttle passage 010 is provided with a
By moving left and right integrally with the 02, the amount of engagement between the tapered portion 08c and the opening 07a of the communication passage 07 is changed, and the amount of the diaphragm is adjusted.

The spool housing hole 03 is partitioned into a first valve chamber 011 and a second valve chamber 012 by a flow rate adjusting spool 02. The second valve chamber 012 has a flow rate adjusting spool 02 on the union 016 side. A spring 013 biasing toward is provided. The second valve chamber 012 and the pressure fluid supply port 06 are communicated with each other by a fixed throttle passage 020 formed in the casing 01, a back pressure oil passage 019, a communication groove 018 formed in the union 016, and a communication hole 017. When the hydraulic pressure in the pressure fluid supply port 06 becomes maximum, the hydraulic pressure is guided into the second valve chamber 012 through these passages, and the relief (not shown) accommodated in the spool 02 for adjusting the flow rate is provided. The guide valve is opened, the flow adjustment spool 02 moves to the left, the return passage 05 is opened, and the entire amount of oil discharged from the hydraulic pump 014 is returned to the suction side of the hydraulic pump 014. 015 is a hydraulic pump
The inlet at 014, 021 is a blind plug that blocks the back pressure oil passage 019.

[0004] Since the conventional flow control device for power steering is constructed as described above, when the pump 014 is rotating in a low speed range, the pressure fluid discharged from the pump 014 is supplied to the fixed throttle passage 09. When the pressure fluid having a flow rate proportional to the pump rotation speed flows out to the pressure fluid supply port 06 via the pump, and the rotation speed of the pump 014 reaches the medium speed range, the supply passage
Since a part of the pressure fluid in 04 is returned to the return passage 05 in response to the increase in the rotation speed of the pump 014, the flow rate of the pressure fluid flowing out to the pressure fluid supply port 06 through the fixed throttle passage 09 is substantially constant. When the rotation speed of the pump 014 is further increased, the pin member 08 moves to the left, and the variable throttle passage 010 is gradually narrowed.
0, the flow rate of the pressure fluid flowing out to the pressure fluid supply port 06 gradually decreases in accordance with the increase in the rotation speed of the pump 014, and after the rotation speed of the pump 014 reaches a predetermined high-speed rotation speed. The flow rate of the pressure fluid flowing out to the pressure fluid supply port 06 is maintained at a substantially constant flow rate lower than the middle speed range.

[0005]

However, in the prior art described above, the fixed throttle passage 09 and the variable throttle passage 01
A union 016 separate from the casing 01 is used to form the communication passage 07 which is one of the elements forming the zero. Therefore, the structures of the fixed throttle passage 09, the variable throttle passage 010, and the pressure fluid supply port 06 are complicated.

[0006] The pressure fluid supply port 06 has a small-diameter port 06a for accommodating the protruding portion of the pin member 08 and a large-diameter port 06b for connecting a pipe for guiding the pressure fluid to the power steering device. The structure is arranged in series in the length direction of the flow control device, and the size of the flow control device as a whole in the length direction increases, making it difficult to reduce the size of the flow control device. Further, the number of processing steps for the oil passage such as the communication hole 017, the communication groove 018, and the bent portion of the back pressure oil passage 019 on the communication groove 018 side is large, and the blind plug 021 is required, so that the cost is high.

[0007]

SUMMARY OF THE INVENTION The present invention relates to an improvement of a flow control device for a power steering which overcomes the above-mentioned drawbacks. The pressure fluid discharged from the pump whose pump discharge flow rate increases in response to the above is supplied to the power steering device through a plurality of throttle passages in the supply passage, and the excess pressure fluid is returned to adjust the opening degree of the passage. In a power steering flow control device that recirculates to a suction side of the pump via a first valve chamber of an adjustment spool valve, the plurality of throttle passages are arranged in series with a fixed throttle passage and the fixed throttle passage. The fixed throttle passage and the variable throttle passage are connected to a spool housing hole of the flow rate adjusting spool valve and a hydraulic fluid supply to the power steering device. And a pin member protruding from an end of the spool on the side of the hydraulic fluid supply chamber and penetrating the communication passage and having a tapered portion at an intermediate portion, the hydraulic fluid being formed by the spool. The supply chamber has a diameter larger than that of the spool housing hole, is provided in a side wall of the casing of the pump, and is a back pressure oil passage connecting the pressure oil fluid supply chamber and a second valve chamber of the flow rate adjusting spool valve. Is formed in the casing of the pump so as to open along the spool housing hole and into the pressure oil fluid supply chamber.

According to the first aspect of the present invention, the pressure oil fluid supply chamber having a larger diameter than the spool housing hole is formed in the side wall of the casing of the pump. Is used as a communication passage for forming a fixed throttle passage and a variable throttle passage, and a union separate from the casing is used to form a communication passage for the same purpose. Since there is no need, the structure of the throttle passage and the portion of the hydraulic fluid supply chamber is simplified.

Further, the pressure oil fluid supply chamber is shared by a chamber for accommodating the protruding portion of the pin member and a chamber for connecting a pipe for guiding the pressure fluid to the power steering device. The overall length dimension can be reduced, and the entire flow control device can be reduced in size.
Furthermore, since the back pressure oil passage is directly opened to the pressure oil fluid supply chamber, the number of processing steps of the oil passage is reduced, a blind plug is not required, and the cost is reduced.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the invention described in claim 1 of the present application shown in FIGS. 1 to 7 will be described below. In these drawings, a casing 1 of the power steering flow control device of the present embodiment is provided with a spool accommodation hole 3 in which a flow adjustment spool 2 is slidably fitted. A supply passage 4 and a return passage 5 are formed at a predetermined distance in the direction, and a pressure fluid supply chamber for supplying a pressure fluid to a power steering device is provided on a right side wall of the casing 1 in the drawing. 6 is provided, and the pressure fluid supply chamber 6 is provided.
A communication passage 7 for communicating these with the spool housing hole 3 is formed. The communication passage 7 has a circular cross section and is formed such that the central axis thereof coincides with the central axis of the spool housing hole 3. The casing 1 of the flow control device is manufactured integrally with the casing of the hydraulic pump 14.

Here, the pressure fluid supply chamber 6 has a larger diameter than the spool housing hole 3, and a back pressure oil passage 19 described later is formed in the casing 1 along the spool housing hole 3 and substantially parallel to the spool housing hole 3. At this time, it is sufficiently large so that its end directly opens into the pressure fluid supply chamber 6.

In the opening of the pressure fluid supply chamber 6,
A union 16 is integrally fitted, and a pipe (not shown) is connected to the union 16 so that a passage inside the union 16 is connected thereto.
Pressurized fluid is supplied to the power steering device of the vehicle via 16c. The union 16 is fitted to the opening of the pressure fluid supply chamber 6 along the side wall of the casing 1, thereby further reducing the size of the entire flow control device.

At the end of the flow rate adjusting spool 2 on the side of the pressure fluid supply chamber 6, a pin member 8 penetrating through the communication passage 7 is projected, and the pin member 8 is shown in detail in FIG. As shown in FIG. 3, the small diameter portion 8a at the base end, the large diameter portion 8b at the distal end, and a tapered portion 8c connecting the three portions, the outer peripheral surface of the small diameter portion 8a and Due to the minute gap between the outer peripheral surface of the large-diameter portion 8b at the tip and the inner peripheral surface of the communication passage 7, two types of fixed throttle passages 9 large and small depending on the position of the pin member 8 are formed. 8c,
A variable throttle passage 10 is formed by the opening 7 a of the communication passage 7 on the side of the pressure fluid supply chamber 6.

The variable throttle passage 10 is connected to the pin member 8.
Moves right and left integrally with the spool 2 for flow adjustment, the length of contact and separation between the tapered portion 8c and the opening 7a of the communication passage 7 is changed, and the amount of throttle is adjusted. The pin member 8 is manufactured separately from the flow rate adjusting spool 2 and is welded thereto.
Further, it may be manufactured integrally with the flow rate adjusting spool 2.

Further, the spool housing hole 3 is partitioned by a flow control spool 2 into a first valve chamber 11 and a second valve chamber 12, and the flow control spool 2 is provided in the second valve chamber 12. Spring 13 biasing toward bottom wall 3a of storage hole 3
Is interposed. The second valve chamber 12 and the pressure fluid supply chamber 6 are connected to a fixed throttle passage 20 formed in the casing 1.
When the hydraulic pressure in the pressure fluid supply chamber 6 is maximized, the hydraulic pressure is guided to the second valve chamber 12 through these passages, and The relief guide valve (not shown) accommodated in the spool 2 opens, the spool 2 for flow adjustment moves to the left, and the return passage 5 opens,
The entire amount of oil discharged from the hydraulic pump 14
To the suction side. Reference numeral 15 denotes an inlet of the hydraulic pump 14.

The flow control device of the present embodiment configured as described above operates as follows. First, in the state illustrated in FIG. 1, when the pump 14 starts rotating in a low-speed region equal to or lower than a predetermined low-speed rotation speed Na, the pressure fluid discharged from the pump 14 flows from the supply passage 4 to the first valve chamber 11. The fixed throttle passage 9 is opened by moving the flow adjusting spool 2 to the left in the drawing within a range in which the communication between the supply passage 4 and the return passage 5 is interrupted (see FIG. 2). Restrictor passage 9
A pressure fluid having a flow rate proportional to the pump rotation speed flows out to the pressure fluid supply chamber 6 via the pump, and is further supplied to a power steering device (not shown) (see FIG. 7A).

Next, when the rotation speed of the pump 14 reaches a middle speed range from a predetermined low rotation speed Na to a predetermined medium rotation speed Nb, the flow rate adjusting spool 2 further moves to the left. 3, the supply passage 4 and the return passage 5 are communicated with each other, and a part of the pressure fluid in the supply passage 4 is returned to the return passage 5 in response to an increase in the rotation speed of the pump 14. Therefore, the flow rate of the pressure fluid flowing from the supply passage 4 to the pressure fluid supply chamber 6 via the first valve chamber 11 and the fixed throttle passage 9 is kept substantially constant (see FIG. 7B).

Further, the pump 14 operates at a predetermined medium speed Nb.
When the pressure fluid reaches the high-speed region beyond the above, the state shown in FIG. 4 is reached, and the pressure fluid flowing from the supply passage 4 into the first valve chamber 11 is
In order to move the flow rate adjusting spool 2 further to the left, and at the same time, gradually allow the tapered portion 8c of the pin member 8 to gradually enter the communication passage 7, the variable throttle passage 10 is gradually narrowed. The flow rate of the pressure fluid flowing into the pressure fluid supply chamber 6 through the variable throttle passage 10 gradually decreases in proportion to the increase in the rotation speed of the pump 14 (see FIG. 7C).
After the number of rotations reaches the predetermined high-speed rotation number Nc and the variable throttle passage 10 is reduced to the predetermined maximum amount, the pin member 8 further moves to the left, and the large-diameter portion 8b at the tip ends. After entering the communication path 7 (see FIG. 5), the throttle amount becomes the maximum constant value,
The flow rate of the pressure fluid flowing into the pressure fluid supply chamber 6 is maintained at a substantially constant flow rate lower than the middle speed range (see FIG. 7D).

In this embodiment, the pressure oil fluid supply chamber 6 having a diameter larger than that of the spool accommodation hole 3 is configured as described above.
Is formed in the side wall of the casing 1 of the pump 14, and a communication passage 7 that communicates with the spool housing hole 3 is provided with a fixed throttle passage 9.
The variable throttle passage 10 is used as a communication passage which is one of the elements forming the throttle passage. Therefore, unlike the related art, it is not necessary to use a union separate from the casing 1 in order to form a similar communication passage, so that the structures of the throttle passages 9 and 10 and the hydraulic fluid supply chamber 6 are simplified. .

Further, since the pressure oil fluid supply chamber 6 is made larger than the conventional pressure oil fluid supply port and also serves as a chamber for accommodating the projecting portion of the pin member 8, the length of the flow rate control device in the longitudinal direction is increased. The dimensions are reduced, which can be miniaturized.

The back pressure oil passage 19 is formed along the spool housing hole 3 and substantially parallel to the spool housing hole 3. The end of the back pressure oil passage 19 is directly opened to the pressure oil fluid supply chamber 6, so that the oil pressure is reduced. Road man-hours are reduced, blind plugs are not required, and manufacturing costs are reduced.

Further, as described above, it is not necessary to use a union, which is a separate member, to form the communication path, which is one of the elements forming the fixed throttle passage 9 and the variable throttle passage 10, so that the number of parts is reduced. As a result, the cumulative dimensional error due to the combination of parts is reduced, and the dimensional accuracy of these throttle passages is improved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional side view when a power steering flow control device according to an embodiment of the invention described in claim 1 of the present application is in a stationary state.

FIG. 2 is a longitudinal sectional side view of the power steering flow control device in the embodiment of FIG. 1 when the pump rotation speed is in a low speed range of Na or less.

FIG. 3 shows the embodiment of FIG.
FIG. 3 is a view similar to FIG. 2 when the vehicle is in a medium speed range up to b.

FIG. 4 is a diagram illustrating an embodiment of FIG.
FIG. 3 is a view similar to FIG. 2 in a high-speed region up to c.

FIG. 5 is a view similar to FIG. 2 in the embodiment of FIG. 1 when the pump rotation speed is in a high speed region equal to or higher than Nc.

FIG. 6 is an enlarged vertical sectional side view of a throttle passage portion of the power steering flow control device in the embodiment of FIG. 1;

FIG. 7 is a characteristic diagram of the flow control device for power steering in the embodiment of FIG. 1;

FIG. 8 is a vertical side view of a conventional power steering flow control device.

9 is an enlarged vertical sectional side view of a throttle passage portion of the conventional power steering flow control device of FIG. 8, which is similar to FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Casing, 2 ... Spool for flow control, 3 ... Spool accommodation hole, 4 ... Supply passage (pump discharge passage), 5 ... Return passage, 6 ... Pressure fluid supply chamber, 7 ... Communication passage, 8 ... Pin member, 9 ... fixed throttle passage, 10 ... variable throttle passage, 11 ... first valve chamber, 12 ... second valve chamber, 13 ... spring, 14 ... pump, 15 ...
Inlet, 16… Union, 17… Communication hole, 18… Communication groove,
19: Back pressure oil passage, 20: Fixed throttle passage.

Claims (1)

[Claims] 1. A pressure fluid discharged from a pump whose pump discharge flow rate increases in response to an increase in the pump rotation speed is supplied to a power steering device through a plurality of throttle passages in a supply passage, and an excess pressure fluid is discharged. In a power steering flow control device that recirculates to a suction side of the pump through a first valve chamber of a flow adjustment spool valve that adjusts an opening degree of a return passage, the plurality of throttle passages include: a fixed throttle passage; A variable throttle passage arranged in series with the fixed throttle passage, wherein the fixed throttle passage and the variable throttle passage are a spool housing hole of the flow rate adjusting spool valve and a pressure oil fluid supply chamber to the power steering device. And a pin member projecting from the end of the spool on the side of the hydraulic fluid supply chamber and penetrating through the communication path and having a tapered portion at an intermediate portion. The pressure oil fluid supply chamber is a larger diameter than the spool housing hole, drilled in the casing side wall of the pump, the second said hydraulic oil fluid supply chamber and the flow rate regulating spool valve
A flow control device for power steering, wherein a back pressure oil passage connecting to a valve chamber is formed in a casing of the pump so as to open along the spool housing hole and to the pressure oil fluid supply chamber. .