JPH0426771Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a pressure control valve installed in a hydraulic circuit of a power steering device of an automobile, for example.

(Prior Art) A hydraulic circuit of a power steering system for an automobile is equipped with a pressure control valve as shown in FIG. 4, for example. In the figure, 100 indicates a fluid chamber 10 inside.
0a, this fluid chamber 100a
are communicated with the inlet 101 and the outlet 102, respectively. Further, inside the valve body 100, a plunger 103 is slidably installed to communicate and cut off the inlet port 101 and the outlet port 102. Further, 104 is a solenoid that operates the plunger 103 in the valve opening direction, and 105 is a solenoid that operates the plunger 103.
3 is a spring that operates in the valve closing direction.

According to the pressure control valve, the solenoid 10
When the valve 4 is not energized, the plunger 103 is biased by the spring 105 in the valve closing direction (downward in FIG. 4), thereby blocking the inlet 101 and the outlet 102. When the solenoid 104 is energized from this state, the plunger 103 is moved by the spring 105.
The pressure oil is sucked in the valve opening direction (upward in the figure) against the elastic force of , the inlet 101 and the outlet 102 communicate with each other, and the pressure oil flows from the inlet 101 to the outlet 102 . Here, by controlling the current to the solenoid 104, the suction force changes, that is, the opening area of the passage that communicates the inlet 101 and the outlet 102 changes, and the pressure of the pressure oil can be controlled.

In the pressure control valve, the plunger 103 is provided with a through hole 106 along the axial direction,
A portion of the pressure oil is directed to the back of the plunger 103. In this way, the plunger 10
The pressure of the pressure oil (positive pressure) acting on the valve portion 3 (positive pressure) and the pressure of the pressure oil (back pressure) acting on the back portion are balanced, and it is possible to substantially prevent oil pressure from acting on the plunger 103. Therefore, the plunger 103
The spring force (elastic force) of the spring 105 that urges the plunger 103 in the valve closing direction does not need to take into account the pressure of the pressure oil and is relatively weak.
The amount of current applied to the solenoid 104 that sucks in the valve opening direction can also be relatively small.

(Problems to be Solved by the Invention) However, in the conventional pressure control valve, when the solenoid 104 is energized, the plunger 103 is attracted, and the inlet 101 and the outlet 102 are separated.
When the passage between the inlet 101 and the outlet 102 starts to open, the pressure oil on the valve side of the plunger 103 instantaneously flows out to the outlet 102, causing a situation in which the positive pressure acting on the valve part of the plunger 103 becomes smaller than the back pressure acting on the back part. In other words, the differential pressure between the positive pressure and the back pressure and the elastic force of the spring 105 act simultaneously on the plunger 103 against the suction force of the solenoid 104. For this reason, when the solenoid 104 starts to be energized, the pressure difference between the positive pressure and the back pressure acts on the plunger 103 simultaneously against the suction force of the solenoid 104.
When the passage between the inlet 101 and the outlet 102 opens only slightly, or opens once and then closes, and as the amount of current increases, the suction force overcomes the combined force of the pressure difference and the elastic force, the passage between the inlet 101 and the outlet 102 opens wide in an instant, and pressure oil flows from the inlet 101 to the outlet 102, after which the positive pressure and back pressure are balanced and the condition stabilizes.

At this time, the relationship between the current flowing through the solenoid and the pressure of the pressure oil changes rapidly, as shown by dotted line A in FIG. In other words, instead of the pressure gradually decreasing after the valve begins to open, the pressure does not decrease for a certain period of time after the valve begins to open (until the suction force overcomes the differential pressure and elastic force), and the pressure does not decrease for a certain period of time after the valve begins to open. There was a problem where the value suddenly decreased after a period of time. For this reason, there has been an inconvenience that as the steering continues, when the steering force changes from a heavy state to a light state, it changes rapidly.

One way to solve this problem is to change the current waveform applied to the solenoid 104 in accordance with the state of the force acting on the plunger, but this creates a new problem of complicating the circuit configuration and increasing costs. was occurring.

Furthermore, in the through hole 106 of FIG.
It is also conceivable to install the inserts described in No. 133174. That is, this insert is made of a material with a larger coefficient of thermal expansion than the plunger 103, and an orifice having a smaller diameter than the through hole 103 is formed in the insert.
With this configuration, even if the pressure oil on the valve side instantaneously flows out to the discharge port 102 and the positive pressure acting on the valve decreases as described above, the throttle flow path will prevent the pressure oil on the back side from flowing out. Since there is a time delay in back pressure fluctuations, the balance between positive pressure and back pressure is less likely to be lost.

However, the above-mentioned insert only expands, contracts, and restricts the flow path area of the flow path naturally depending on changes in the temperature of the pressure oil. Therefore, not only is it impossible to adjust the flow path area in a strict sense, that is, adjustment corresponding to conditions other than artificial adjustment or temperature changes, but also the flow path area of the throttle flow path may penetrate depending on the temperature of the pressure oil. Hole 1
The area would be the same as that of 03, or even larger, and there was a risk that the aperture function would be lost.

Therefore, the present invention was devised to solve the above-mentioned problems of the prior art, and its purpose is to smoothly change pressure without increasing costs, such as hydraulic pressure in power steering equipment. It is an object of the present invention to provide a pressure control valve that not only does not cause any inconvenience when applied to a circuit, but also can accurately adjust the flow area of a throttle flow path.

(Means for Solving the Problems) In order to achieve the above object, the present invention includes a valve body having an inlet and an outlet, and a valve body that is slidably provided in the valve body and has an inlet and an outlet. The plunger is equipped with a plunger for communicating and blocking the outlet, a biasing means for biasing the plunger in the valve-closing direction, and a solenoid for suctioning the plunger in the valve-opening direction against the biasing means. In the pressure control valve, the plunger is provided with a through hole in the direction so as to apply fluid pressure to a valve part of the plunger located on the inlet side and a back part located on the opposite side of the valve part. A screw hole communicating with the through hole and having a larger diameter than the through hole is provided on the back side of the through hole, and a dome-shaped screw hole whose diameter increases from the through hole toward the screw hole is provided between the screw hole and the through hole. By providing a throttle hole, and inserting into the screw hole a throttle screw having a threaded portion that engages with the screw hole, and a conical portion whose diameter increases from the through-hole side toward the back side, A throttle passage is formed between the conical part and the throttle hole, and a communication passage is provided in the threaded part to communicate the back part and the throttle passage.

(Function) In the present invention having the above configuration, the fluid acting on the valve part of the plunger also acts on the back part through the through hole, so the pressure of the fluid on the valve part side (positive pressure) and the pressure of the fluid on the back side (back pressure) is in a balanced state. When the passage between the inlet and the outlet begins to open, the fluid momentarily flows toward the outlet and the positive pressure decreases, but the fluid circulates through the throttle channel at the back of the plunger. Therefore, a situation in which the balance between positive pressure and back pressure is disrupted does not substantially occur.
Therefore, it is possible to smoothly change the pressure in proportion to the amount of current applied.

Also, if you move the aperture screw along the screw hole,
The flow area of the throttle flow path can be adjusted accurately.

(Example) The present invention will be explained below based on the illustrated example.

FIG. 1 shows an embodiment of a pressure control valve according to the present invention. In the figure, 1 is a valve body, and an inlet 2 and an outlet 3 are provided at one end in the axial direction.
A plunger 4 that communicates with and blocks the introduction port 2 and the discharge port 3 is provided so as to be slidable in the axial direction. Also, a solenoid 5 is installed on the outer periphery of the valve body 1 from the middle to the other end to suck the plunger 4 in the valve-opening direction (the direction that communicates the inlet 2 and the outlet 3, upward in the drawing). A center post 6 coaxial with the plunger 4 is provided inside the center of the valve body 1.

The center post 6 is arranged such that one end thereof is located on the back portion 50 side located on the end surface of the plunger 4, and an azimuth star 7 is disposed inside the center post 6.
is fitted so as to be movable in the axial direction. and,
A spring 8 is provided between the adjuster star 7 and the back portion 50 of the plunger 4 as a biasing means for biasing the plunger 4 in the valve-closing direction (direction that blocks the inlet 2 and discharge port 3, downward in the drawing). is mediated. In addition, a screw member 9 for stopper and adjustment is screwed into the screw hole 6a at the opening at the other end of the center post 6, and the screw member 9 moves the adjuster star 7 in the axial direction to compress the spring 8. By changing the amount, the set load (spring force) of the spring 8 is adjusted.

A through hole 10 is formed in the plunger 4 along the axial direction, and a part of the fluid existing on the valve portion 51 side of the plunger 4 passes through the through hole 10 to the back portion 50.
It is configured to rotate to the side. In this way, the fluid pressure (positive pressure) acting on the valve portion 51 on the end face facing the inlet 2 side of the plunger 4 and the fluid pressure (back pressure) acting on the back portion 50 are balanced, and the plunger 4 is substantially This prevents fluid pressure from acting on it.

The through hole 10 of the plunger 4 is equipped with a throttle mechanism 11, which is a characteristic feature of the present invention. This throttle mechanism 11 is formed on the back 50 side of the plunger 4, as shown in FIG. Screw hole 1 from through hole 10 side
A cone-shaped aperture hole 12 whose diameter expands toward the 2a side
A throttle screw 1 which integrally has a threaded part 13a screwed into the screw hole 12a and a conical part 13b inserted into the throttle hole 12b in a mounting part 12 having a screw hole 12b.
It is constructed by attaching 3. As shown in Figure b, the circumferential surface of the threaded portion 13a is provided with a communication groove 13a' extending in the axial direction as a communication path, and the end surface thereof is provided with an engagement groove 13a'' extending in the radial direction. There is.

Further, insert a tool such as a screwdriver into the hole 9a of the screw member 9 to engage the flat operation plate 7a (see c in the same figure) provided on the adjuster star 7 with the engagement groove 13a'', and use the screwdriver to engage the adjuster star 7. This operation causes the threaded portion 13a to rotate within the threaded hole 12a and move in the axial direction, reducing the flow area of the throttle channel 52 between the throttle hole 12b and the conical portion 13b. is adjusted.

A step 6b is provided at an intermediate position inside the center post 6, and a spring 14 is interposed between the step 6b and the adjuster star 7. This spring 14 is connected to the throttle channel 52.
After adjustment (after aperture adjustment), adjuster star 7
It has the effect of returning it to its original position. Furthermore, the inner surface of the valve seat 15 that forms the inlet 2 and the valve portion of the plunger 4 that comes into contact with the inner surface have a rough surface so that the plunger 4 does not rotate during adjustment of the throttle flow path 52 (during throttle adjustment). is formed. Furthermore, a spring 8 is attached to the back portion 50 of the plunger 4.
A spacer 16 made of a non-magnetic material is provided to prevent the disc from shifting.

According to the pressure control valve, the solenoid 5 does not operate when the current is not energized, and the plunger 4 is moved to the valve seat 15 by the set load of the spring 8.
The inlet port 2 and the outlet port 3 are blocked by contacting the inlet port 2 and the outlet port 3.

When the solenoid 5 is energized, the suction force of the solenoid 5 acts on the plunger 4 and the plunger 4 moves in the valve opening direction against the set load of the spring 8, causing pressure oil to flow from the inlet port 2 to the discharge port 3. flows. When the passage between the inlet port 2 and the outlet port 3 begins to open, pressure oil instantaneously flows into the outlet port 3, so that the positive pressure on the valve portion 51 side of the plunger 4 becomes small.

However, the pressure oil circulating to the back 50 side is in the throttle hole 12b.
Since the flow rate is restricted when passing through the throttle channel 52 between the conical portion 13b and the conical portion 13b, there is a slight time delay in pressure fluctuations on the back pressure side, and even if the positive pressure momentarily decreases, the back pressure does not change. does not become relatively large, so a situation where the balance between positive pressure and back pressure is disrupted does not substantially occur.

Furthermore, when the suction force increases due to an increase in the amount of current flowing through the solenoid 5, the plunger 4 sequentially moves in one direction, increasing the opening area of the passage between the inlet 2 and the outlet 3, and increasing the pressure of the pressure oil. gradually decreases as shown by solid line B in FIG.

Therefore, by equipping the hydraulic circuit of a power steering device with the above-mentioned pressure control valve, it is possible to gradually reduce the pressure of the pressure oil flowing into the hydraulic circuit, thereby preventing a situation where the steering force changes suddenly. does not occur.

Incidentally, the operating characteristics of the plunger 4 change depending on various conditions such as the properties and pressure of the flowing fluid, the dimensions of the plunger 4 and the valve body 1, and variations in assembly. For example, if the clearance between the sliding surfaces of the valve body 1 and the plunger 4 varies from product to product, the operating characteristics will change due to the frictional resistance of the sliding surfaces, which will affect the pressure control characteristics.

Even under such conditions, the present invention can prevent the drawing screw 13 from
By moving the flow path area of the throttle channel 52 (adjust the throttle) in response to the above-mentioned variations, it is possible to adjust the pressure control characteristics of the product to a predetermined value as a result.

In addition, since the flow area of the throttle channel 52 does not change unless the throttle screw 13 is moved by human operation, the flow channel area does not change naturally due to changes in the pressure oil temperature, etc., and is stable. The aperture function can be maintained.

In the above embodiment, when the flow path area of the flow path 52 is changed and increased, the pressure control valve is applied to reduce the pressure of the fluid in proportion to this. It can also be applied to a pressure control valve that reduces the pressure of a fluid proportionally when the amount is reduced.

(Effects of the Invention) The present invention has the above-mentioned configuration and effect, and by providing a throttle flow passage in the plunger's through hole, it is possible to smoothly change pressure without increasing costs, and no inconvenience occurs when applied to the hydraulic circuit of a power steering device.

In addition, if conditions such as the clearance between the sliding surface of the valve body and the plunger vary from product to product, the operating characteristics will change due to the frictional resistance of the sliding surface, which will affect the pressure control characteristics. It will be extended. Even under such conditions, the present invention can accurately adjust the flow area of the throttle channel to accommodate the above variations by moving the throttle screw, and as a result, the pressure control characteristics of the product can be adjusted to a predetermined value. can.

In addition, since the flow area of the throttle passage does not change unless the throttle screw is moved by human operation, the flow passage area does not change naturally due to changes in the pressure oil temperature, etc., and the throttle remains stable. Can maintain functionality.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the pressure control valve according to the present invention, FIG. 2a is a partially enlarged sectional view showing the throttle mechanism part of the valve in detail, and FIG. FIG. 3c is a partial perspective view showing the operating plate portion of the adjuster, FIG. 3 is a graph showing the relationship between the amount of current and pressure, and FIG. 4 is a sectional view of a conventional pressure control valve. Explanation of symbols: 1... Valve body, 2... Inlet, 3... Outlet, 4... Plunger, 5... Solenoid, 50... Back, 51... Valve part, 52...
... Throttle channel, 8... Biasing means (spring), 1
0... Through hole, 11... Throttle mechanism, 12... Attachment part (screw hole 12a, throttle hole 12b), 13... Throttle screw (threaded part 13a, conical part 13b).

Claims (1)

[Scope of Claim for Utility Model Registration] A valve body having an inlet and an outlet, a plunger that is slidably provided within the valve body to communicate and shut off the inlet and the outlet, and a plunger that connects the plunger in the valve closing direction. and a solenoid that suctions the plunger in the valve opening direction against the urging means, and an axial through hole is provided in the plunger, and the plunger is provided with an inlet side. In a pressure control valve configured to apply fluid pressure to a valve portion located at the rear portion of the plunger and a back portion located on the opposite side of the valve portion, the back portion of the plunger is connected to the through hole, and the through hole is connected to the rear portion of the plunger. A screw hole with a larger diameter than the hole is provided, a dome-shaped throttle hole whose diameter increases from the through hole toward the screw hole is provided between the screw hole and the through hole, and the screw hole is inserted into the screw hole. By inserting a throttle screw having a threaded portion that is screwed into the through-hole and a conical portion whose diameter increases from the through-hole side toward the back side, a throttle flow path is created between the conical portion and the throttle hole. The pressure control valve is characterized in that the threaded portion is provided with a communication path that communicates the back portion and the throttle flow path.