JP3632771B2 - Relief pressure adjustment device - Google Patents

Description

[0001]
[Industrial application fields]
The present invention has a built-in relief valve that supplies the pressure fluid discharged from the pump to an actuator such as a power steering of a vehicle via a throttle passage in the supply passage, and adjusts the opening of the return passage with excess pressure fluid. In the flow rate control device that recirculates to the pump suction side by the mold flow rate adjusting spool valve, the fluctuation of the relief pressure of the relief valve built in the flow rate adjusting spool valve can be suppressed and the relief pressure can be adjusted. The present invention relates to a relief pressure adjusting device that can be used.
[0002]
[Prior art]
The conventional flow control device is configured as shown in FIGS.
5 to 6, the discharge port 02 of the vane pump 01 communicates with the flow rate adjusting spool valve housing hole 04, and the supply passage 06 communicates with, for example, a power steering (not shown) via the throttle 05. It is communicated to.
[0003]
Further, a flow rate adjusting spool valve 07 is slidably fitted in the flow rate adjusting spool valve accommodation hole 04, and the flow rate adjusting spool valve accommodation hole 04 serves as a pump discharge port 02. Is divided into a valve chamber 08 and a pilot pressure chamber 09, which communicate with the supply passage 06 through a throttle 010.
[0004]
Further, a compression coil spring 011 is interposed in the pilot pressure chamber 09, and the spool pressing force due to the oil pressure in the valve chamber 08 is the spool pressing force due to the oil pressure in the pilot pressure chamber 09 and the spring of the compression coil spring 011. When the sum with the force is exceeded, the return port 012 is opened, and the pressure oil in the valve chamber 08 is returned to the suction port 03 of the vane pump 01.
[0005]
Furthermore, a relief valve 013 is incorporated in the flow rate adjusting spool valve 07, and the relief valve 013 is a ball seat 014 screwed to the end of the flow rate adjusting spool valve 07 on the pilot pressure chamber 09 side, A ball 017 that can contact the opening of the communication hole 016 provided in the ball seat 014 so as to communicate with the space 015 in the pilot pressure chamber 09 and the flow rate adjusting spool valve 07 and close the communication hole 016; A spring guide 018 that clamps the ball 017 together with the ball seat 014, and a relief spring 019 that presses the ball 017 against the opening of the communication hole 016 via the spring guide 018, and an oil pressure in the pilot pressure chamber 09 To press the ball 017 to open the opening of the communication hole 016 However, when the set load of the relief spring 019 is exceeded, the pressure oil in the pilot valve pressure chamber 09 returns to the suction port 03 of the vane pump 01 through the communication hole 016, the space 015, and the through hole 020, and the pilot pressure With the discharge of the pressure oil in the chamber 09, the flow rate adjusting spool valve 07 moves so as to widen the return port 012. Thus, the oil pressure in the supply passage 06 is maintained below the required relief pressure. Yes.
[0006]
[Problems to be solved]
5 to 6, in order to adjust the relief pressure in the supply passage 06, the set load of the relief spring 019 may be changed. For this purpose, the flow rate adjusting spool valve 07 and the ball seat are changed. In addition, one or more shims 020 having a required thickness had to be selectively inserted.
[0007]
Therefore, in the flow rate control apparatus shown in FIGS. 5 to 6 in which the flow rate adjusting spool valve 07 is integrally incorporated in the main body of the vane pump 01, the relief pressure is adjusted when the pump assembly is assembled. Is substantially impossible, and it is difficult to improve the relief pressure adjustment accuracy.
[0008]
Further, since the diameter and length of the throttle 010 for damping the vibration of the flow rate adjusting spool valve 07 when the relief valve 013 is opened and closed cannot be adjusted, the vibration damping characteristic of the flow rate adjusting spool valve 07 is changed. I could not.
[0009]
[Means for solving the problems and effects]
The present invention relates to an improvement of a flow rate control device that overcomes such difficulties, and supplies pressure fluid discharged from a pump to an actuator via a throttle passage in a supply passage, and surplus pressure fluid is returned to an opening of a return passage. In a flow rate control device that recirculates to the suction side of the pump by a flow rate adjusting spool valve with a built-in relief valve that adjusts the flow rate, the relief pressure passage that connects the pilot pressure chamber of the flow rate adjusting spool valve and the actuator device supply passage is restricted. The throttle is variably adjustable from the outside of the flow control device housing.
[0010]
In the present invention, as described above, the relief is connected to the pilot pressure chamber of the spool valve for flow rate adjustment and the actuator supply passage, so that the restriction is variably adjustable from the outside of the flow rate control housing. The relief pressure can be adjusted by adjusting the flow resistance of the relief passage during the relief valve operation without changing the relief spring set load of the relief valve built into the flow rate adjusting spool valve. The vibration damping property of the adjusting spool valve can be changed.
[0011]
Further, in the present invention, the variable throttle has an adjustment rod penetrating the flow control device housing and having a distal end projecting freely into and out of the relief passage and screwed into the housing, and a lock nut for fixing the adjustment rod Therefore, the relief pressure can be finely adjusted, the variable throttle can be held firmly and constant, and the variable throttle can be simplified in structure to reduce the cost.
[0012]
Furthermore, in the present invention, the relief passage is inclined obliquely with respect to the main relief passage disposed on the extension line of the adjustment rod and the center line of the adjustment rod in the vicinity of the tip of the adjustment rod. Since it is constituted by the inclined relief passage communicating with the control pressure chamber of the spool valve, the structure of the relief passage can be simplified and the cost in this aspect can be reduced.
[0013]
As described above, in the present invention, the relief pressure can be easily adjusted by adjusting the flow resistance of the relief passage during the relief valve operation without disassembling the flow control device. Productivity can be significantly improved by greatly simplifying the adjustment work after assembly.
[0014]
Further, according to the present invention, since the relief pressure can be finely adjusted, the adjustment accuracy of the flow control device can be improved, and a homogeneous flow control device can be easily produced.
[0015]
【Example】
An embodiment in which the present invention shown in FIGS. 1 and 2 is applied to a power steering flow control device will be described below.
A vane hydraulic pump 3 driven by a belt or the like from an engine (not shown) is integrally incorporated in the housing 2 of the pump speed-sensitive power steering flow control device 1, and the discharge flow rate of the hydraulic pump 3 is determined by the rotation of the engine. The number increases or decreases in proportion to the number of rotations of the hydraulic pump 3.
[0016]
In the housing 2, a flow rate adjusting spool storage hole 5 communicating with the discharge passage 4 of the vane hydraulic pump 3 is formed, and a flow rate adjusting spool 6 is slidably fitted in the flow rate adjusting spool storage hole 5. The flow rate adjusting spool housing hole 5 is divided into a valve chamber 7 and a pilot pressure chamber 8 by the flow rate adjusting spool 6.
[0017]
The pilot pressure chamber 8 on the right side of the flow rate adjusting spool housing hole 5 is provided with a compression coil spring 9 that presses against the flow rate adjusting spool 6 toward the valve chamber 7. When the pressure in the pilot pressure chamber 8 becomes equal to or higher than the relief pressure, a relief valve 10 for discharging the pressure oil in the pilot pressure chamber 8 to the return passage 11 communicating with the suction port of the vane hydraulic pump 3 is incorporated. Therefore, the pressure in the pilot pressure chamber 8 is lowered.
[0018]
Accordingly, the relief valve 10 is provided in the ball seat 12 so as to communicate the ball seat 12 screwed to the right end of the flow rate adjusting spool 6 with the pilot pressure chamber 8 and the space 13 in the flow rate adjusting spool 6. A ball 15 that abuts the opening of the communication hole 14 that is closed to close the communication hole 14, a spring guide 16 that clamps the ball 15 together with the ball seat 12, and a communication hole that allows the ball 15 to communicate with the ball guide 12. 14 and the relief spring 17 that presses against the opening 14, and the pressing force to the ball 15 that attempts to open the opening of the communication hole 14 by the hydraulic pressure in the pilot pressure chamber 8 exceeds the set load of the relief spring 17. The pressure oil in the pilot pressure chamber 8 passes through the communication hole 14, the space 13, and the through hole 18. Is discharged to the return passage 11, so that the lower the pressure in the pilot pressure chamber 8.
[0019]
The housing 2 is formed with a cylindrical pressure oil supply hole 19 for supplying pressure oil to a power steering device (not shown) in parallel with the flow rate adjusting spool storage hole 5. It is connected to the power steering device via a connector and a pipe (not shown).
[0020]
Further, the valve chamber 7 and the pressure oil supply hole 19 of the spool housing hole 5 for adjusting the flow rate are connected by a throttle passage 20 and a communication passage 21 in parallel therewith. An outer barrel 22 having a cylindrical end is fitted.
[0021]
Further, the upper end of the outer barrel 22 is cut out in a planar shape, and a locking hole 24 parallel to the center line of the outer barrel 22 opened in the notched portion 23 is formed. The main relief passage 25 is formed in the housing 2 and a spring pin 26 in which a rectangular thin steel plate is formed in a cylindrical shape is fitted into the locking hole 24 and the main relief passage 25, and the spring pin 26, the outer barrel 22 is fixed to the pressure oil supply hole 19.
[0022]
In addition, the outer barrel 22 is formed with a center hole 27 concentric with the center of the outer cylindrical surface of the outer barrel 22 at a predetermined depth from the left side, and a communication hole 28 that connects the center hole 27 and the communication path 21 is provided. In addition, a variable orifice 29 that communicates the center hole 27 and the notch 23 is provided.
[0023]
A control spool 30 is slidably fitted in the center hole 27 of the outer barrel 22, the center hole 27 is closed by the cap 31, and the outer barrel 22 and the control spool 30 are compressed by the center hole 27 of the outer barrel 22. A coil spring 32 is interposed, and the control spool 30 is pressed against the cap 31 by the spring force of the compression coil spring 32.
[0024]
Further, the main relief passage 25 is once reduced in diameter to the right and then gradually increased in diameter so that the tip end portion 34 of the adjustment rod 33 can be loosely fitted to the right end portion of the main relief passage 25. The adjustment rod 33 is screwed to the housing 2, and the adjustment rod 33 is fixed by a lock nut 35 screwed to the adjustment rod 33.
[0025]
Furthermore, an inclined relief passage 36 that communicates the main relief passage 25 and the pilot pressure chamber 8 is located to the right of the tip 34 of the adjustment rod 33 and opens to the main relief passage 25.
[0026]
Moreover, the control pressure chamber 37 sandwiched between the control spool 30 and the cap 31 includes an oil passage (not shown) provided in the control spool 30, an oil passage 38 provided in the outer barrel 22, and an oil passage 39 provided in the housing 2. Is connected to the discharge port of the vane hydraulic pump 3, and pressure oil higher than the pressure oil pressure in the center hole 27 is introduced into the control pressure chamber 37.
[0027]
Since the embodiment shown in FIGS. 1 and 2 is configured as described above, the flow rate adjusting spool 6 is pushed to the left by the spring force of the compression coil spring 9 when the vane hydraulic pump 3 is stopped. Thus, the discharge passage 4 and the return passage 11 are blocked by the flow rate adjusting spool 6, and the control spool 30 is pushed to the left by the spring force of the compression coil spring 32 so that the variable orifice 29 is fully opened.
[0028]
Then, in the area from when the vane hydraulic pump 3 starts to rotate until the predetermined low speed is reached, the discharge passage 4 and the return passage 11 remain blocked, and the total pressure oil discharged from the vane hydraulic pump 3 is The valve chamber 7 flows into the notch 23 in the pressure oil supply hole 19 through the throttle passage 20 and is removed from the valve chamber 7 through the communication passage 21, the communication hole 28, the center hole 27 and the variable orifice 29. Flows into the section 23.
[0029]
Moreover, until the predetermined low-speed rotation speed is reached, the pressure adjustment spool 6 overcomes the spring force of the compression coil spring 9 due to the increase in the pressure oil pressure in the valve chamber 7 and moves to the right. Since the return passage 11 remains cut off, the total discharge pressure oil of the vane hydraulic pump 3 that is substantially proportional to the rotational speed of the vane hydraulic pump 3 is supplied to a power steering device (not shown).
[0030]
Further, until the rotational speed of the vane hydraulic pump 3 exceeds the predetermined low speed rotational speed and reaches a predetermined medium speed rotational speed, the flow rate adjustment is performed by the rise of the pressure oil in the valve chamber 7 of the flow rate adjusting spool housing hole 5. Since the spool 6 further moves to the right, the discharge passage 4 and the return passage 11 communicate with each other, and the communication opening area increases corresponding to the increase in the flow rate of the vane hydraulic pump 3. Regardless of the fluctuation of the number, a substantially constant flow of pressure oil is supplied to the power steering apparatus.
[0031]
Further, when the rotation speed of the vane hydraulic pump 3 exceeds a predetermined medium speed rotation speed, a pressure difference obtained by subtracting the pressure oil pressure in the center hole 27 from the pressure oil pressure in the control pressure chamber 37 increases, and the pressure difference The rightward pressing force of the control spool 30 overcomes the spring force of the compression coil spring 32, the control spool 30 moves to the right, the opening area of the variable orifice 29 is reduced, and the communication passage 21, the communication path from the valve chamber 7 is reduced. Since the flow rate of the pressure oil flowing into the notch 23 via the hole 28, the central hole 27 and the variable orifice 29 is decreased, the vane hydraulic pump 3 is operated until the vane hydraulic pump 3 reaches a predetermined high speed from a predetermined medium speed. The amount of oil supplied to the power steering device decreases corresponding to the increase in the rotational speed of the hydraulic pump 3.
[0032]
Furthermore, when the rotational speed of the vane hydraulic pump 3 reaches a predetermined high speed rotational speed, the control spool 30 is moved to the right side by increasing the pressure difference obtained by subtracting the pressure oil pressure in the center hole 27 from the pressure oil pressure in the control pressure chamber 37. Further, the variable orifice 29 is completely closed, and only the pressure oil that has passed through the throttle passage 20 is supplied to the power steering device. The pilot pressure chamber 8 is supplied with the throttle passage 20, the main relief passage 25, and the slope relief. The pressure oil in the valve chamber 7 is introduced through the passage 36, and the pressure of the pressure oil introduced into the pilot pressure chamber 8 is caused by the throttle passage 20, the main relief passage 25, the variable throttle 40 between the tip portion 34 and Therefore, the flow rate adjusting spool 6 moves further to the right due to the pressure difference between the valve chamber 7 and the pilot pressure chamber 8 and returns to the return passage 11. Increased reflux flow rate And thus the supply amount of oil to the power steering device is held constant amount of oil level lower than a predetermined oil feed amount from a predetermined low rotational speed to the power steering device in the area of a predetermined medium speed rotational speed.
[0033]
When the pressure oil pressure to the power steering device, in other words, the pressure oil pressure in the notch portion 23 of the pressure oil supply hole 19 reaches the maximum value, the main relief passage 25, the variable throttle in the notch portion 23. 40 and the pressure oil pressure in the pilot pressure chamber 8 communicated via the inclined relief passage 36 rises correspondingly, the relief valve 10 is opened, and the pressure oil in the pilot pressure chamber 8 passes through the communication hole 14, Since it is discharged to the return passage 11 through the space 13 and the through hole 18, the flow rate adjusting spool 6 moves to the right, and the pressure oil flowing from the vane hydraulic pump 3 into the valve chamber 7 through the discharge passage 4 is The pressure oil returned to the return passage 11 and in the notch 23 of the pressure oil supply hole 19 does not exceed the maximum value.
[0034]
Further, since the notch 23 and the pilot pressure chamber 8 are communicated with each other via the variable throttle 40, when the relief valve 10 is opened, the inside of the pilot pressure chamber 8 is compared with the pressure oil pressure of the notch 23. The pressure oil pressure is maintained at a low pressure, but after the lock nut 35 is loosened, the adjustment rod 33 is screwed so that the distal end portion 34 enters or exits deep inside the main relief passage 25, thereby removing the missing portion. The flow resistance from 23 to the pilot pressure chamber 8 is increased or decreased to increase or decrease the amount of decrease in the pressure oil pressure from the notch 23 to the pilot pressure chamber 8, and the relief pressure of the relief valve 10 is Can be finely adjusted within the range.
[0035]
According to experiments, when the length of the variable throttle 40 is changed in the range of 0 to 5 mm, the relief pressure can be changed by about 10%. Further, when the thickness of the variable throttle 40 is different by 0.25 mm, the relief pressure changes by about 15%.
[0036]
Further, when the length of the variable throttle 40 was changed in the range of 0 to 5 mm, the relief valve 10 did not generate chattering, and the flow rate adjusting spool 6 could avoid unstable vibration.
[0037]
As described above, the relief pressure can be easily and finely adjusted without disassembling the housing 2 and taking out the flow rate adjusting spool 6 from the housing 2.
[0038]
In the embodiment shown in FIGS. 1 and 2, the variable throttle 40 is constituted by the cylindrical surface in the main relief passage 25 and the cylindrical surface of the tip 34 of the adjustment rod 33. As shown in FIG. The distal end portion 41 of the adjustment rod 33 may be formed in a truncated cone shape, and the variable restrictor 42 may be configured by the cylindrical surface of the main relief passage 25 and the distal end portion 41 of the adjustment rod 33 formed by the truncated cone surface. Also in the embodiment, the same operational effects as those in the embodiment of FIGS.
[0039]
Further, as shown in FIG. 4, the tip portion 43 is formed so that the diameter of the tip portion 43 of the adjustment rod 33 matches the diameter of the main relief passage 25 at the portion communicating with the inclined relief passage 36. Thus, the opening of the inclined relief passage 36 may be formed in the variable throttle 44, and the same effects as those of the above-described embodiment can be achieved.
[0040]
In the above-described embodiment, the flow rate control device is a variable flow rate type flow rate control device in which the flow rate is changed in response to a change in the number of rotations of the pump.
[Brief description of the drawings]
FIG. 1 is a longitudinal side view of an embodiment in which the present invention is applied to a power steering flow control device.
FIG. 2 is an enlarged vertical side view of the main part of FIG. 1;
FIG. 3 is an enlarged longitudinal sectional side view of a main part of another embodiment of the present invention.
FIG. 4 is an enlarged longitudinal sectional side view of a main part of still another embodiment of the present invention.
FIG. 5 is a schematic explanatory diagram of a conventional flow rate control device.
6 is an enlarged vertical sectional side view of a main part of FIG. 5. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Flow rate control apparatus for pump rotation speed sensitive type power steering, 2 ... Housing, 3 ... Vane hydraulic pump, 4 ... Discharge passage, 5 ... Spool accommodation hole for flow control, 6 ... Spool for flow control, 7 ... Valve chamber, 8 ... Pilot pressure chamber, 9 ... Compression coil spring, 10 ... Relief valve, 11 ... Return passage, 12 ... Ball seat, 13 ... Space, 14 ... Communication hole, 15 ... Ball, 16 ... Spring guide, 17 ... Relief spring, DESCRIPTION OF SYMBOLS 18 ... Through-hole, 19 ... Pressure oil supply hole, 20 ... Restriction passage, 21 ... Communication passage, 22 ... Outer barrel, 23 ... Deletion part, 24 ... Locking hole, 25 ... Main relief passage, 26 ... Spring pin, 27 ... Center hole, 28 ... Communication hole, 29 ... Variable orifice, 30 ... Control spool, 31 ... Cap, 32 ... Compression coil spring, 33 ... Adjustment rod, 34 ... Tip, 3 ... lock nut, 36 ... inclined relief passage, 37 ... control pressure chamber, 38, 39 ... oil passage 40 ... variable throttle, 41 ... tip portion, 42 ... variable throttle, 43 ... tip portion, 44 ... variable throttle.

Claims (3)

The pressure fluid discharged from the pump is supplied to the actuator via the throttle passage in the supply passage, and the excess pressure fluid is supplied to the suction side of the pump by a flow control spool valve with a built-in relief valve that adjusts the opening degree of the return passage. In the flow control device for recirculation, a throttle is provided in a relief passage communicating the pilot pressure chamber of the spool valve for flow control and the actuator supply passage, and the throttle can be variably adjusted from the outside of the flow control device housing. A relief pressure adjusting device characterized by that. The variable throttle includes an adjustment rod penetrating through the flow control device housing and projecting so as to protrude and retract into the relief passage and screwed into the housing, and a lock nut for fixing the adjustment rod. The relief pressure adjusting device according to claim 1. The relief passage is inclined with respect to the main relief passage disposed in the extension line of the adjustment rod and the center line of the adjustment rod in the vicinity of the tip of the adjustment rod, and the control pressure of the flow rate adjusting spool valve The relief pressure adjusting device according to claim 2, comprising an inclined relief passage communicating with the chamber.

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