JPH09126332A - Spool valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To sense a spool displacement rate when a spool is moved in a right direction while using a sensor having a short sensing stroke. SOLUTION: A sensor 9 for detecting the expandable and contractible rate of a sensor rod 9a as displacement of a spool 6 is arranged on one end side of the spool 6, and a spring center mechanism 8 is attached to the end of a side provided with the sensor 9 of the spool 6. The position of the left side spring retainer 8b is interlocked with the spool 6 when the spool 6 is moved in a right direction, and it is stopped in a condition in which the spool 6 is in a neutral condition when the spool 6 is moved in a left direction, and the sensor rod 9a is driven to the left side spring retainer 8b. It is thus possible to sense the displacement rate of the spool 6 when the spool 6 is moved in a right direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spool valve preferably used for a valve for driving a cargo handling machine such as a forklift.

[0002]

2. Description of the Related Art The spool switching of a spool valve has a function of controlling the flow rate of the hydraulic fluid, as well as switching the supply target of the hydraulic fluid. The flow rate is controlled by adjusting the stroke amount to adjust the opening area formed between the spool insertion groove and each port. For example, in a battery forklift, the cargo handling speed is controlled by such a method.

In controlling the flow rate, by controlling only the valve on the outflow side without controlling the pump for pumping the pressurized liquid, for example, when it is desired to slowly move the actuator connected to the valve, a small flow rate is required. A large amount of pressure oil is injected into the valve, which causes inefficiency such as squeezing it with the valve. In order to improve such inefficiency, in recent years,
Utilizing the fact that the rotation speed control of the DC motor is facilitated by the chopper, a sensor for knowing the spool position is installed on the spool shaft to change the spool position into an electric signal, and the pump that is the hydraulic pressure source is used by that signal. It has become common to control and regulate the flow rate in two stages, the hydraulic source and the outflow side.

An example of a conventional spool valve having such a spool position detecting sensor is shown in FIG. This conventional spool valve controls cargo handling of a single-acting cylinder A that performs a lift action. A spool hole 6b penetrates a valve body B, and the spool hole 6b has a high pressure port 1 connected to a high pressure source. A tank port 2 communicating with a low pressure source and a center bypass 3 communicating with the high pressure port 1 and the tank port 2
Is connected to the actuator port 4, and the spool hole 6
The flow path is switched by the spool 6 sliding in b. A case C for housing the sensor 9 is provided on the extension of the spool shaft center at the left end of the valve body B.

FIG. 4 shows the spool 6 in the neutral position. When the spool 6 is in the rightward position, the center bypass 3 is closed, the high pressure port 1 is connected to the actuator port 4, and the load supported by the actuator is lifted. When the spool 6 is in the leftward position, the center bypass 3 is closed, the tank port 2 is connected to the actuator port 4, and the load supported by the actuator is lowered. When the spool 6 is in the neutral position, the center bypass 3 is opened and the actuator port 4 is blocked from the high pressure port 1 and the tank port 2.

That is, if the position of the spool 6 is expressed with the sensor 9 as a reference, the load supported by the actuator is lifted when the spool 6 is farther from the sensor than the neutral position, and the spool 6 is moved from the neutral position. When on the sensor side, the load supported by the actuator is reduced.

The right side portion of the case C is a spring center chamber 8c for accommodating the spring center mechanism 8. The spring center mechanism 8 separates two spring retainers 8b, each having a concave disk-shaped center and a circular hole, with spool outer springs 8a provided between the edges of the recesses so that the outer bottoms of the recesses are close to each other. It is a combination of urging. At the spool left end 6a of the spool 6, a set consisting of a set screw body 7b, which is a cylinder having a common axis and a diameter smaller than that of the spool 6, and a set screw left end 7a, which is a disk having a diameter slightly larger than the set screw body 7b. Screw 7 is provided, 2
The set screw body 7b passes through the two spring retainers 8b.

When no force is applied to the spool 6, the two spring retainers 8b are separated from the right end to the left end of the spring center chamber 8c by the urging force of the spool spring 8a, and the spring center mechanism 8 returns the spool 6 to the neutral position. . When the spool 6 is moved to the right, the left end 7a of the set screw hooks the left spring retainer 8b and moves right while the left end 6a of the spool 6 and the right spring retainer 8b are separated from each other. When the spool 6 is moved to the left, the left end 6a of the spool moves to the left and is pushed by it, so that the right side spring retainer 8b also moves to the left, but the left side spring retainer 8b hits the inner wall of the spring center chamber 8c, so it cannot be moved. Instead, only the left end 7a of the set screw moves to the left.

Further to the left of the left end 7a of the set screw,
A sensor 9 including a linear sensor 9b and a sensor rod 9a, which is a rod that extends and contracts to the right from the axis of the linear sensor 9.
Is located. The right end of the sensor rod 9a comes into contact with the left end 7a of the set screw to expand and contract according to the displacement of the left end 7a of the set screw, and an electric signal is output from the linear sensor 9b according to the amount of expansion and contraction, and the hydraulic power source motor is controlled.

[0010]

In order to detect all the spool positions, the sensing stroke of the sensor 9 must extend from the left row position of the spool 6 to the right row position of the spool 6. However, since a sensor with a long sensing stroke is expensive, depending on the application of the spool valve,
It is possible to reduce the cost by measuring only the displacement of the required part and performing the same function by using a sensor with a shorter sensing stroke.

For example, in the single-acting cylinder A having the lift action shown in FIG. 4, since the lift-down is performed by the descent by the weight of the actuator, the sensing by the sensor 9 for controlling the motor is necessary only during the lift-up. Since the load is lifted by moving the spool 6 to the rightward position as described above, in such a single acting cylinder A, the displacement of the spool 6 is detected.
It suffices to perform only between the rightward position and the neutral position of the spool 6, and the sensing stroke of the sensor 9 is the length from the rightward position of the spool 6 to the neutral position of the spool 6, that is, half the total stroke amount.

However, in the conventional spool valve shown in FIG. 4,
If the sensing stroke of the sensor 9 is from the spool rightward position to the spool neutral position, the displacement when the spool 6 is rightward cannot be detected. The reason is as follows.

When the sensor 9 is arranged so that the tip of the sensor 9 abuts the left end 7a of the set screw when the spool 6 moves to the left when the sensor rod 9a is shortest.
Is fully extended at the spool 6 neutral position, and the spool 6
When moving to the right, only the left end 7a of the set screw moves.

On the other hand, when the sensor 9 is arranged so that its tip contacts the left end 7a of the set screw when the spool 6 is in the neutral position when the sensor rod 9a is shortest, the sensor rod 9a exceeds the stroke end of the sensor 9 when the spool 6 moves to the left. The motion sensor 9 is destroyed.

As described above, in the conventional spool valve, there is a limitation that the position of the spool 6 can be sensed only when the spool 6 moves leftward. Therefore, even when it is advantageous to use the spool 6 in the rightward position, it is used in the leftward position. I dealt with it by changing the reverse link and changing the piping.

In view of the above problems of the prior art, the present invention uses a sensor having a short sensing stroke, and
An object of the present invention is to provide a spool valve capable of sensing the amount of spool displacement even when the spool moves in a direction away from the sensor rather than the neutral position.

[0017]

SUMMARY OF THE INVENTION The present invention is a spool valve for solving the above-mentioned problems, in which a destination of pressure fluid is switched by a spool that slides in a one-dimensional direction. Is provided with a sensor that has a sensor rod and detects the amount of expansion and contraction of the sensor rod as the displacement of the spool. A spring center mechanism that combines two spring retainers is attached to the end of the spool on the sensor side. The position of the sensor-side spring retainer of the spring center mechanism is interlocked with the sensor when the spool is farther from the neutral position than the neutral position, and is far from the sensor when the spool is closer to the sensor than the neutral position. The sensor rod is configured to remain in its current state. Characterized in that it is configured to follow the movement of the sensor-side spring retainer motor mechanism.

The structure in which the sensor rod follows the movement of the sensor side spring retainer is, for example,
A component that contacts the sensor-side spring retainer when the spool moves to the left, but does not always contact the left end of the set screw, such as a sensor plate that is always interlocked with the spool, is always biased and contacted to the sensor-side spring retainer. Can be achieved with.

With such a configuration, if the sensor is arranged at a position where the tip of the shortest sensor rod comes into contact with the sensor-side spring retainer when the spool is neutral, the spool moves from the sensor. When moving to the distant side, the sensor rod extends corresponding to the movement of the sensor side spring retainer and the spool displacement amount can be known, and when the spool moves to the sensor side, the sensor side spring retainer does not move. Therefore, the sensor rod does not move and does not receive the axial force directly from the spool to break the sensor unlike the conventional case.

In this way, according to the present invention, the sensor is used to sense the spool position even when the sensor has a sensing stroke that is only half the moving range of the spool and the spool moves in a direction away from the sensor rather than the neutral position. It becomes possible. Therefore, it is not necessary to use a sensor with a long sensing stroke, and the cost can be reduced. In addition, there is no need to deal with reverse links or changes in piping, and it is possible to freely select the mounting direction, which was previously restricted, and the best layout is possible. Further, even if a spool valve to be attached later is attached to the already completed cargo handling control system, it can be attached without changing the piping and links.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION A spool valve V according to an embodiment of the present invention will be described below with reference to FIGS. In addition,
Regarding the basic structure common to conventional spool valves,
Description will be given using the same reference numerals as those of the conventional spool valve.

A spool valve V according to the present invention shown in FIG. 1 controls cargo handling of a single-acting cylinder A that acts on a lift.
A spool hole 6b penetrates the valve body B, and a high pressure port 1 connected to a high pressure source, a tank port 2 communicating with a low pressure source, and a center connecting the high pressure port 1 and the tank port 2 are communicated with the spool hole 6b. The bypass 3 is connected to the actuator port 4, and the flow path is switched by the spool 6 that slides in the spool hole 6b. A case C for housing the sensor 9 is provided on the extension of the spool shaft center at the left end of the valve body B.

FIG. 1 shows the spool 6 in the neutral position. The operations of the spool 6 when moving to the right, to the neutral, and to the left are the same as those of the conventional spool valve, and therefore description thereof is omitted. Similar to the conventional spool valve, the load supported by the actuator is lifted when the spool 6 goes to the right, that is, when the spool 6 is farther from the neutral position than the sensor 9, and when the spool 6 goes to the left, that is, the spool 6 is in the neutral position. When the position is closer to the sensor 9 than the position, the load supported by the actuator is reduced.

At the right side of the case C, there is a spring center chamber 8c. On the valve body B side in the spring center chamber 8c, the center is a concave disk, the edge diameter is larger than the spool 6, the inner diameter of the recess is approximately equal to the spool 6, and the diameter in the center of the recess is approximately equal to the set screw 7. Two spring retainers 8b with circular holes are
The spring center mechanism 8 is constituted by bringing the outer bottoms of the recesses close to each other and urging the spool springs 8a so that their edges are separated from each other.

At the spool left end 6a of the spool 6, a set screw body 7b, which is a cylinder having a common axis and a diameter smaller than that of the spool 6, and a set screw left end 7a, which is a disk having a slightly larger diameter than the set screw body, are provided. The set screw 7 is provided to penetrate the two spring retainers 8b with the left end 7a of the set screw extending to the left end. The length of the set screw main body 7b in the spool shaft center direction is determined by the left and right spring retainers 8b.
Is equal to the distance between the inner bottoms of the recesses when they are maximally separated.

On the side of the sensor 9 in the spring center chamber 8c, the sensor plate 1 is a flat disk with a diameter equal to that of the spring retainer 8b or a disk with a slightly concave center.
0 is placed. If the left end 7a of the set screw projects to the left of the left side spring retainer 8b when the spool 6 moves to the left, the center of the right side of the sensor plate 10 is made concave, otherwise, the shape of the sensor plate 10 is made into a flat disk. The sensor plate 10 is the sensor spring 1
It is constantly urged by 1 and contacts the left side spring retainer 8b. The sensor plate 10 is the spring center chamber 8
Since the two spring retainers 8b are spaced apart from each other, the two spring retainers 8b are separated from each other by maximally separating their edges from each other.
Due to the maximum, the valve body B of the spring center chamber 8c
This is when the sensor plate 10 is separated from the side wall.

The action of the spring center mechanism 8 is also conventional except that the edge of the left spring retainer 8b when the two spring retainers 8b are maximally separated is in contact with the sensor plate 10 instead of the wall of the spring center chamber 8c. The description is omitted because it is the same as the spool valve.

A sensor 9 including a linear sensor 9b and a sensor rod 9a which is a rod extending rightward from the axis of the linear sensor 9 is located further to the left of the sensor plate 10, and the right end of the sensor rod 9a is conventionally formed. In contrast to the contact with the left end 7a of the set screw, in the present embodiment, it contacts the sensor plate 10 and expands and contracts according to the position of the sensor plate 10, and an electric signal is output from the linear sensor 9b according to the expansion and contraction amount. , The hydraulic source motor is controlled.

In such a spool valve, the sensor 9
Is arranged so that the tip of the sensor plate 10 contacts the left end of the left side spring retainer 8b when the spool 6 is neutral when the sensor rod 9a is shortest. If you do this,
When the spool 6 moves to the right, as shown in FIG.
Similarly, 0 goes rightward while contacting the left side spring retainer 8b, and the sensor rod 9a also extends in response to this, and the linear sensor 9b detects the displacement amount of the spool 6. On the contrary, when the spool 6 moves to the left, as shown in FIG.
Since the left side spring retainer 8b is released from the spool 6 and does not move, the spool 6 is attached to the sensor rod 9a.
Is not directly applied, and the sensor 9 is not destroyed. Of course, the sensor rod 9a does not interfere with the leftward movement of the spool 6.

In this way, the spool valve V according to the embodiment of the present invention uses the sensor 9 having a sensing stroke of only half the moving range of the spool 6, and
It is possible to sense the spool position when the spool 6 moves to the right. Therefore, it is not necessary to use a sensor with a long sensing stroke, and cost reduction is achieved.

Further, since there is no restriction on the mounting direction of the arrangement of the spool valve, it is not necessary to deal with it by changing the reverse link or changing the piping, and the best layout is possible. Also, even if a spool valve to be installed later is attached to the already completed system, it can be attached without changing the piping and links.

The present invention is not limited to the embodiment described above, and various modifications can be made without departing from the spirit of the present invention. For example, when the sensor is arranged on the right end side of the spool, it is possible to detect the displacement when the spool moves to the left. It is also possible to integrate the sensor side spring retainer and the sensor plate into a single component. Further, the sensor plate may be biased by a spring built in the sensor instead of a separate sensor spring.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view of an embodiment of the present invention.

FIG. 2 is an operation explanatory view when the spool moves rightward according to the embodiment of the present invention.

FIG. 3 is an operation explanatory view when the spool moves to the left according to the embodiment of the present invention.

FIG. 4 is a horizontal vertical sectional view of a conventional spool valve.

[Explanation of Codes] 6 ... Spool 8 ... Spring center mechanism 8b ... Spring retainer 9 ... Sensor 9a ... Sensor rod V ... Spool valve

Claims (1)

[Claims] 1. A spool valve for switching the destination of pressure fluid by means of a spool that slides in a one-dimensional direction, wherein a sensor rod is provided at one end of the spool, and the expansion / contraction amount of the sensor rod is used as the displacement of the spool. A sensor for detection is provided, and a spring center mechanism in which two spring retainers are combined is attached to the end of the spool on the side where the sensor is present. The position of the sensor side spring retainer of the spring center mechanism is such that the spool is neutral. The sensor rod is configured to move away from the sensor when the spool moves closer to the sensor than the position, and to remain in the spool neutral state when the spool moves closer to the sensor than the neutral position. Follow the movement of the spring retainer on the sensor side of the center mechanism. Spool valve, characterized by being made.