JP2005035481A - Flow control valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flow control valve, preventing abrasion of the bottom of a discharge recessed part and its periphery even if cavitation occurs. <P>SOLUTION: In this flow control valve, when a discharge passage 5 and a discharge communicating passage 29 are communicated with a supply passage 4 according to a moving position of a spool 7, some of pressure oil from the supply passage 4 is guided as a surplus flow to the discharge passage 5, and the pressure oil flowing from the supply passage 4 through the discharge communicating passage 29 into an annular groove 7c of the spool 7 is guided to the discharge passage 5. The wall surface of the annular groove 7c is covered with a hard member 30 harder than aluminum. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a flow rate control valve that controls a flow rate that is led to an actuator port by discharging an excessive flow rate into a discharge passage.

FIG. 2 shows a circuit diagram of a power steering apparatus provided with a flow control valve FV. As shown in the figure, a power steering mechanism PS is connected to the discharge port 1 a of the pump 1 through a flow path 2. A variable orifice 3 and a flow control valve FV are provided in the middle of the flow path 2.
The flow control valve FV has a supply passage 4, a discharge passage 5, and a spool hole 6 formed in the body 10. A spool 7 is slidably incorporated in the spool hole 6, and a pilot chamber 8 is formed by the spool 7 and the spool hole 6. A spring 9 is provided in the pilot chamber 8, and the elastic force of the spring 9 is applied to one end 7 a of the spool 7.

A pressure downstream of the variable orifice 3 is guided to the pilot chamber 8 through a pilot passage 27. The pressure downstream of the variable orifice 3 is applied to one end 7 a of the spool 7.
On the other hand, a pressure upstream of the variable orifice 3 is applied to the other end 7 b of the spool 7. Therefore, the spool 7 moves to a position where the pressure action on the one end 7a side and the spring force of the spring 9 balance with the pressure action on the other end 7b side. The communication area between the supply passage 4 and the discharge passage 5 is determined according to the position where the spool 7 has moved.
When the supply passage 4 and the discharge passage 5 communicate with each other, a part of the oil discharged from the pump 1 is returned to the tank T through the discharge passage 5 as an excessive flow rate.

FIG. 3 is a cross-sectional view showing a specific structure of the pump 1 and the flow control valve FV.
As shown in the figure, a housing H composed of an aluminum body 10 and an aluminum cover 11 is formed with shaft holes 12 and 12, and bearings 13 and 13 are provided in the shaft holes 12. The shaft 14 is rotatably supported by these bearings 13 and 13.
A rotor 15 that houses a plurality of vanes 16 so as to protrude freely is fixed to the shaft 14. A cam ring 17 having a substantially elliptic inner wall is provided around the rotor 15, and a side plate 18 is brought into contact with the cam ring 17.

The body 10 incorporates a flow control valve FV. As shown in FIG. 4, the flow control valve FV has a supply passage 4, a discharge passage 5, and a spool hole 6 formed in the body 10, and the supply passage 4 and the discharge passage 5 are opened to the spool hole 6. Yes. In addition, an aluminum spool 7 is slidably incorporated in the spool hole 6, and the supply passage 4 and the discharge passage 5 are connected to each other according to the movement position of the spool 7, or the communication is blocked. I try to do it.
When the pump 1 is stopped, the spool 7 maintains the position shown in the figure by the elastic force of the spring 9 provided in the pilot chamber 8 and blocks the communication between the supply passage 4 and the discharge passage 5.
A connector 21 is inserted and fixed to the other end side of the spool hole 6. The connector 21 is provided with an actuator port 21 a and a cylindrical member 23 having a through hole 22 on the inner periphery of the connector 21.

On the other hand, a rod member 24 is fixed to the other end 7 b side of the spool 7, and the rod member 24 is passed through the through hole 22. The variable orifice 3 is configured by the gap between the rod member 24 and the through hole 22.
The rod member 24 is press-fitted as a separate member from the spool 7 in FIG. 4, but may be integrated with the spool 7.
Further, the opening of the variable orifice 3 is maximized when the spool 7 is in contact with the stopper 23a via the rod member 24 due to the elastic force of the spring 9 as shown. When the spool 7 moves against the spring 9, the large diameter portion 24a approaches the through hole 22, and the opening of the variable orifice 3 is reduced accordingly.

The connector 21 has a pressure sensing hole 25 and an annular groove 26. The annular groove 26 is communicated with the pilot chamber 8 via a pilot passage 27 formed in the body 10 so that the pressure downstream of the variable orifice 3 is guided to the pilot chamber 8.
Note that reference numeral R in the figure denotes a relief valve, which is supplied to the power steering mechanism PS and regulates the maximum pressure.

  When the shaft 14 shown in FIG. 3 is rotated by a drive source (not shown), the rotor 15 also rotates. When the rotor 15 rotates in this manner, the vane 16 protrudes from the rotor 15 due to the centrifugal force or the like, but the inner wall of the cam ring 17 has a substantially elliptical shape. Repeat the entry and exit process. Therefore, the tip of each vane 16 rotates while being in close contact with the cam ring 5, and a chamber is formed between each vane 16 in an independent manner.

As described above, the volume of each chamber formed between the vanes 16 changes as the vanes 16 enter and exit along the inner wall surface of the cam ring 17. And when it enters the process of expanding the volume of the chamber, it becomes a suction process of sucking oil from a suction port (not shown). On the other hand, when each chamber starts to shrink, it becomes a discharge step for discharging the oil sucked in the suction step. By repeating the suction process and the discharge process in this way, high-pressure oil is discharged from each chamber.
Further, the pressure oil discharged from each chamber in this way is guided to the high pressure chamber 20 through the discharge flow path 19 formed in the side plate 18.

The pressure oil guided to the high pressure chamber 20 is guided to the flow control valve FV through the supply passage 4. As shown in FIG. 4, the pressure oil guided to the flow control valve FV is guided to the actuator port 21a via the variable orifice 3 and supplied to the power steering mechanism PS (see FIG. 2).
At this time, a pressure difference is generated between the upstream side and the downstream side of the variable orifice 3, but the upstream pressure acts on the other end 7 b of the spool 7, and the downstream pressure passes through the pilot passage 27. It is guided to the pilot chamber 8 and acts on one end 7 a of the spool 7. Therefore, a thrust in the left direction of the drawing is generated in the spool 7 by the pressure on the upstream side of the variable orifice 3.

  When the leftward thrust becomes larger than the initial load of the spring 9, the spool 7 moves against the spring 9 in the leftward direction in the drawing and maintains a position where the thrust and the elastic force are balanced. When the spool 7 moves to a balanced position in this way, the other end 7b overlaps the discharge passage 5, so that the supply passage 4 and the discharge passage 5 communicate with each other. If the supply passage 4 and the discharge passage 5 communicate with each other in this way, a part of the discharged oil is guided to the discharge passage 5 as an excessive flow rate.

Incidentally, in this conventional example, as shown in FIG. 5, a discharge recess 28 is formed on the inner periphery of the spool hole 6. The discharge recess 28 is formed simultaneously by penetrating the spool hole 6 when the discharge passage 5 is formed in the body 10. That is, the discharge recess 28 is provided at a position facing the opening 5 a of the discharge passage 5 in the spool hole 6.
Therefore, when the supply passage 4 and the discharge passage 5 communicate with each other as described above, the discharge recess 28 also communicates with the supply passage 4. The pressure oil flows into the discharge recess 28 from the supply passage 4 and is guided to the discharge passage 5 through the annular groove 7 c formed in the spool 7.

  The reason why the discharge recess 28 is provided is to prevent the bias of the spool 7 when the excessive flow rate is discharged through the discharge passage 5. That is, when the excessive flow rate is discharged through the discharge passage 5, the pressure in the discharge passage 5 acts on the peripheral surface of the spool 7 at the opening 5a. At this time, if there is no discharge recess 28, a biased force acts on the spool 7 due to the influence of the pressure in the discharge passage 5. When such a biased force acts on the spool 7, the spool 7 is pressed against the inner periphery of the spool hole 6, so that the spool 7 is worn or the smooth movement of the spool 7 is hindered. Further, if the spool 7 is worn away, the flow rate control characteristics may also change.

  However, as described above, if the discharge recess 28 is provided at a position facing the opening 5 a of the discharge passage 5, the pressure action on the discharge passage 5 side is canceled by the pressure action in the discharge recess 28. Therefore, it is possible to prevent a biased force from acting on the spool 7 and to avoid the inconvenience. For this reason, the discharge recess 28 is provided at a position facing the opening 5 a of the discharge passage 5.

JP-A-7-217550 (FIG. 1)

However, in the above conventional example, when a part of the excessive flow rate flows into the discharge recess 28, cavitation occurs in the discharge recess 28 due to a rapid pressure drop. When cavitation occurs in the discharge recess 28 as described above, the body 10 is made of aluminum, so that the bottom and surroundings of the discharge recess 28 are worn or corroded by erosion. If such a phenomenon continues for a long time, there is a problem that a hole is formed in the body 10.
In addition, when the bottom and periphery of the discharge recess 28 are scraped by erosion, contamination such as shavings is generated, and this contamination is sucked into the vane pump as it is, thereby causing a problem that the discharge performance is lowered.

  In order to solve such a problem, it is conceivable to suppress a rapid pressure drop in the discharge recess 28. As a specific means for suppressing a sudden pressure drop, it is conceivable to reduce the volume in the discharge recess 28. This is because if the volume in the discharge recess 28 is reduced, the portion exhibits the same function as the choke, so that the discharged pressure oil can be gradually lowered.

However, when this is done, the pressure drop increases when the pressure oil flows into the annular groove 7 c of the spool 7 from the inside of the discharge recess 28. Therefore, cavitation occurs in the annular groove 7c of the spool 7 and the aluminum spool 7 is worn away.
Accordingly, an object of the present invention is to provide a flow rate control valve that can prevent wear of the spool 7 even if cavitation occurs when an excess flow rate flows into the annular groove 7c of the spool 7.

  The first invention is an aluminum body, a supply passage and a discharge passage formed in the body, a spool hole communicating with the supply passage and the discharge passage, and an aluminum body slidably incorporated in the spool hole. A spool, an annular groove formed in the spool, an actuator port connected to the supply passage side of the spool hole, an orifice provided in the middle of the flow path between the supply passage and the actuator port, and an actuator port of the spool hole A pilot chamber provided on the opposite side to the pilot chamber, a pilot passage for introducing pressure downstream of the orifice into the pilot chamber, a spring provided in the pilot chamber and applying an elastic force to the spool, and an inner wall of the spool hole. A discharge communication passage formed at a position facing the opening of the discharge passage, and the discharge passage and When the outgoing communication passage communicates with the supply passage according to the moving position of the spool, a part of the pressure oil from the supply passage is led to the discharge passage as an excessive flow rate, and from the supply passage through the discharge communication passage. In the flow control valve for guiding the pressure oil flowing into the annular groove of the spool to the discharge passage, the surface of the annular groove is covered with a hard member harder than aluminum.

  The second invention is an aluminum body, a supply passage and a discharge passage formed in the body, a spool hole communicating with the supply passage and the discharge passage, and an aluminum body slidably incorporated in the spool hole. A spool, an annular groove formed in the spool, an actuator port connected to the supply passage side of the spool hole, an orifice provided in the middle of the flow path between the supply passage and the actuator port, and an actuator port of the spool hole A pilot chamber provided on the opposite side to the pilot chamber, a pilot passage for introducing pressure downstream of the orifice into the pilot chamber, a spring provided in the pilot chamber and applying an elastic force to the spool, and an inner wall of the spool hole. A discharge communication passage formed at a position facing the opening of the discharge passage, and the discharge passage and When the outgoing communication passage communicates with the supply passage according to the moving position of the spool, a part of the pressure oil from the supply passage is led to the discharge passage as an excessive flow rate, and from the supply passage through the discharge communication passage. The flow rate control valve for guiding the pressure oil flowing into the annular groove of the spool to the discharge passage is characterized in that a hard member harder than aluminum is coated on the surface of the annular groove.

  A third invention is an aluminum body, a supply passage and a discharge passage formed in the body, a spool hole communicating with the supply passage and the discharge passage, and an aluminum body slidably incorporated in the spool hole. A spool, an annular groove formed in the spool, an actuator port connected to the supply passage side of the spool hole, an orifice provided in the middle of the flow path between the supply passage and the actuator port, and an actuator port of the spool hole A pilot chamber provided on the opposite side to the pilot chamber, a pilot passage for introducing pressure downstream of the orifice into the pilot chamber, a spring provided in the pilot chamber and applying an elastic force to the spool, and an inner wall of the spool hole. A discharge communication passage formed at a position facing the opening of the discharge passage, and the discharge passage and When the outgoing communication passage communicates with the supply passage according to the moving position of the spool, a part of the pressure oil from the supply passage is led to the discharge passage as an excessive flow rate, and from the supply passage through the discharge communication passage. In the flow control valve for guiding the pressure oil flowing into the annular groove of the spool to the discharge passage, the surface of the annular groove is subjected to a hardening process such as heat treatment.

  According to the first invention, since the surface of the annular groove is covered with a hard member harder than aluminum, even if cavitation occurs in the annular groove, it is possible to prevent wear of the wall surface of the annular groove. .

  According to the second invention, since the surface of the annular groove is coated with a hard member harder than aluminum, even if cavitation occurs in the annular groove, it is possible to prevent wear of the wall surface of the annular groove. .

  According to the third invention, since the surface of the annular groove is subjected to a hardening process such as heat treatment, even if cavitation occurs in the annular groove, it is possible to prevent the wall surface of the annular groove from being worn.

  FIG. 1 shows an embodiment of the present invention. The configuration other than the point that the discharge recess 28 of the conventional example is used as the discharge communication passage 29 and the point that the cover member 30 is provided in the annular groove 7c of the spool 7 are described above. Conventional Example Same as FIG. 2, FIG. 3, FIG. Therefore, in the following description, the discharge communication passage 29 and the spool 7 will be mainly described, and the same components as those in the related art will be denoted by the same reference numerals and detailed description thereof will be omitted.

  As shown in FIG. 1, a spool hole 6 is formed in an aluminum body 10, and a discharge passage 5 is communicated with the spool hole 6. An aluminum spool 7 is slidably incorporated in the spool hole 6, and an annular groove 7c is formed in the spool 7. An iron cover member 30 harder than aluminum is attached to the bottom of the annular groove 7c in an annular shape. The cover member 30 is fixed to the annular groove 7c using welding, an adhesive, or the like, but may be fixed using other means.

Further, a discharge communication passage 29 is formed at a position on the inner periphery of the spool hole 6 and facing the opening 5 a of the discharge passage 5. As shown in FIG. 1, the discharge communication passage 29 has a depth H smaller than a depth h of the conventional discharge recess 28 (see FIG. 5). Thus, by reducing the depth H of the discharge communication passage 29, the volume of the discharge communication passage 29 is reduced. If the volume of the discharge recess 29 is reduced in this way, as described above, since the discharge recess 29 performs the same function as the choke, the discharged pressure oil can be gradually reduced.
Therefore, cavitation can be prevented from occurring in the discharge communication passage 29.

The pressure oil that has flowed into the discharge communication passage 29 suddenly decreases when it flows into the annular groove 7 c of the spool 7.
As described above, cavitation occurs because of a rapid pressure drop in the annular groove 7c. As described above, the iron cover member 30 is provided at the bottom of the annular groove 7c. Accordingly, the cover member 30 is not worn or scraped by cavitation, and the bottom of the annular groove 7c can be prevented from being worn.

  That is, according to this embodiment, cavitation is positively generated in the annular groove 7c of the spool 7, and the bottom of the annular groove 7c in which cavitation is generated is covered with the iron cover member 30 that is harder than aluminum. This prevents wear of the spool 7 and the like. In this way, the aluminum spool 7 is not perforated, and the bottom of the annular groove 7c is not scraped by erosion. And the problem that the discharge performance of a vane pump falls by contamination mixing does not arise.

  In addition, the cover member 30 in the said embodiment is corresponded to the hard member harder than the aluminum in this invention. In the above embodiment, only the bottom portion of the annular groove 7 c is covered with the iron cover member 30, but the entire surface of the annular groove 7 c may be covered with the cover member 30. The cover member 30 is not limited to iron as long as it is harder than aluminum.

In the above embodiment, the cover member 30 is assembled in the annular groove 7c to prevent inconvenience due to cavitation. However, the surface of the annular groove 7c may be coated with a hard member harder than aluminum.
Further, the surface of the annular groove 7c may be subjected to a hardening process such as a heat treatment to prevent wear due to the cavitation.

  As described above, in the case of a curing process such as coating or heat treatment, it is not necessary to assemble a new member in the annular groove 7c of the spool 7 as a measure against erosion of the annular groove 7c of the spool 7. Therefore, measures against erosion of the annular groove 7c of the spool 7 can be realized without adding new members.

Furthermore, in the above embodiment, the pressure oil discharged from the vane pump is controlled, but the flow control valve of the present invention can also control the pressure oil supplied from other pressure sources such as a gear pump. . Moreover, in the said embodiment, although the excess flow volume is returned to the suction side of a vane pump via the discharge channel 5, you may return an excess flow volume to a tank.
However, according to the present invention, contamination can be prevented from being mixed into the surplus flow rate. Therefore, when the surplus flow rate is used in a vane pump that directly leads to the suction side via the discharge passage 5, the discharge performance of the vane pump is reduced. The effect that it can maintain is acquired.

It is sectional drawing of embodiment of this invention. It is a circuit diagram of the power steering device provided with the flow control valve FV. It is sectional drawing of a vane pump. It is sectional drawing of a prior art example. It is explanatory drawing of the flow control valve FV.

Explanation of symbols

DESCRIPTION OF SYMBOLS 3 Variable orifice 4 Supply passage 5 Discharge passage 6 Spool hole 7 Spool 7c Annular groove 8 Pilot chamber 9 Spring 10 Body 21a Actuator port 27 Pilot passage 29 Discharge communication passage 30 Cover member equivalent to the rigid member of this invention

Claims (3)

  An aluminum body, a supply passage and a discharge passage formed in the body, a spool hole communicating with the supply passage and the discharge passage, an aluminum spool slidably incorporated in the spool hole, and the spool An annular groove formed, an actuator port communicating with the supply passage side of the spool hole, an orifice provided in the middle of the flow path between the supply passage and the actuator port, and provided on the opposite side of the actuator port of the spool hole A pilot passage for guiding the pressure downstream of the orifice into the pilot chamber, a spring provided in the pilot chamber and applying an elastic force to the spool, an inner wall of the spool hole, A discharge communication passage formed at a position facing the opening, and the discharge passage and the discharge communication passage are When communicating with the supply passage according to the movement position of the spool, a part of the pressure oil from the supply passage is led to the discharge passage as an excessive flow rate, and from the supply passage to the annular groove of the spool through the discharge communication passage. A flow rate control valve for guiding pressure oil that has flowed into a discharge passage, wherein a surface of the annular groove is covered with a hard member harder than aluminum.   An aluminum body, a supply passage and a discharge passage formed in the body, a spool hole communicating with the supply passage and the discharge passage, an aluminum spool slidably incorporated in the spool hole, and the spool An annular groove formed, an actuator port communicating with the supply passage side of the spool hole, an orifice provided in the middle of the flow path between the supply passage and the actuator port, and provided on the opposite side of the actuator port of the spool hole A pilot passage for guiding the pressure downstream of the orifice into the pilot chamber, a spring provided in the pilot chamber and applying an elastic force to the spool, an inner wall of the spool hole, A discharge communication passage formed at a position facing the opening, and the discharge passage and the discharge communication passage are When communicating with the supply passage according to the movement position of the spool, a part of the pressure oil from the supply passage is led to the discharge passage as an excessive flow rate, and from the supply passage to the annular groove of the spool through the discharge communication passage. A flow rate control valve for guiding pressure oil that has flowed into a discharge passage, wherein the surface of the annular groove is coated with a hard member harder than aluminum.   An aluminum body, a supply passage and a discharge passage formed in the body, a spool hole communicating with the supply passage and the discharge passage, an aluminum spool slidably incorporated in the spool hole, and the spool An annular groove formed, an actuator port communicating with the supply passage side of the spool hole, an orifice provided in the middle of the flow path between the supply passage and the actuator port, and provided on the opposite side of the actuator port of the spool hole A pilot passage for guiding the pressure downstream of the orifice into the pilot chamber, a spring provided in the pilot chamber and applying an elastic force to the spool, an inner wall of the spool hole, A discharge communication passage formed at a position facing the opening, and the discharge passage and the discharge communication passage are When communicating with the supply passage according to the movement position of the spool, a part of the pressure oil from the supply passage is led to the discharge passage as an excessive flow rate, and from the supply passage to the annular groove of the spool through the discharge communication passage. A flow control valve for guiding pressure oil that has flowed into a discharge passage, wherein the surface of the annular groove is subjected to a hardening process such as a heat treatment.

Images