JPH10274357A - Spool position detecting device for stacked valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To assemble an element in a main body so as to miniaturize a device, and to improve the durability by fitting a pressure sensitive conductive element between a holding spring for holding a spool at a neutral position and the spool, and electrically detecting a change of the pressure to be applied to the pressure sensitive conductive element on the basis of the movement of the spool. SOLUTION: This device 30 is mainly formed of a pressure sensitive conductive element 30 inserted between a spring receiver 23 and a holding spring 22. This pressure sensitive conductive element 30 generates a change of electrical resistance in response to the pressurization. At the time of moving a spool 3, a neutral holding spring 22 is pressurized, and this pressure can be detected as a change of electrical resistance of the pressure sensitive conductive element 30. The pressure sensitive conductive element is formed of an elastic element, which is mainly composed of rubber and elastomer or the like. With this structure, a fine change of the movement of the spool can be accurately detected. Since the pressure sensitive conductive element is compact, a valve main body can be miniaturized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stack valve, and more particularly to a position detecting device for detecting a position of a spool in a stack valve having a spool.

[0002]

2. Description of the Related Art When switching the supply of hydraulic oil to, for example, a cylinder by a stack valve, there is no problem in the case of simple switching between a supply position, a neutral position, and a return position, but fine adjustment of the supply amount. When it is necessary, or when so-called inching or the like is performed, it is necessary to detect the position of the spool. Therefore, as the spool position detecting device, for example, a structure shown in FIG. 4 is employed.

In FIG. 4, a stack valve 1 has a three-position center bypass type spool 3 which is slidably inserted into a valve housing 2. The spool 3 has first and second lands 6 and 7 formed on the left and right sides of the central land 5 at a predetermined interval. In the spool through hole 8 of the valve housing 2, at the neutral position of the spool 3, the center bypass outlet passage 9 is located at the same position as the center land 5, and the center bypass outlet passage 9,
Form 10. Third and fourth lands 11 and 12 are formed at predetermined intervals outside the first and second lands 6 and 7. The valve housing 2 has a first land 6 and a third land 11.
Between the second land 7 and the fourth land 12, and the second cylinder port 14 between the second land 7 and the fourth land 12.
Open. Reference numeral 15 denotes a pressure oil supply passage, and reference numerals 16 and 17 denote pressure oil supply ports connected to the pressure oil supply passage 15 via check valves 18 and 19, respectively. The lands 6 and 7 prevent communication with the cylinder ports 13 and 14. 20
Denotes a low-pressure passage communicating with the tank passage 21, and 22 denotes a spring for holding the spool 4 at a neutral position.

The stack valve 1 is provided with a position detecting device 50 for detecting the forward / backward movement of the spool 3. The detecting device 50 is composed of a sliding resistor. The sliding resistor 50 has a sensor 52 attached to the tip of a connecting rod 51 fixed to the tip of the spool 3, and a fixed member provided to face the sensor 52. And a resistor 53. This fixed resistor 53
Has a length longer than the stroke length of the spool 3. As a result, the sensor 52 shifts following the shift of the spool 3, and the position where the spool moves in and out is determined by the fixed resistor 53.
Can be electrically detected by the change in the resistance value of

[0005]

Since the spool position detecting device 50 is provided so as to protrude from the stack valve 1, the arrangement may be disturbed, and it is difficult to reduce the size of the spool. In addition, since a sliding resistor is used, there is a problem such as deterioration of the resistor. In view of the above, the present invention
An object of the present invention is to provide a detection device which is incorporated in a stack valve and which is small and has high durability.

[0006]

A first aspect of the present invention relates to a spool position detecting device for achieving the above object, and in a stack valve provided with a spool, a holding valve for holding the spool at a neutral position and a spool. A pressure-sensitive conductive element is mounted, and a change in pressure applied to the pressure-sensitive conductive element due to the movement of the spool is electrically detected.

In the present invention having the above structure, the pressure-sensitive conductive element moves together with the spool, and the shift position of the spool can be detected by a change in the spring pressure applied to the spool.

According to a second aspect of the present invention, in a stack valve having a manual spool, a pressure-sensitive conductive element is attached to the spool via a spring, and the pressure-sensitive conductive element is supported by an adjusting screw attached to a proper position of the stack valve housing. The adjustment screw can adjust a spring pressure applied to the pressure-sensitive conductive element, and a change in pressure applied to the pressure-sensitive conductive element due to a shift of the spool is electrically detected.

In the present invention having the above-described structure, the change in the compression pressure of the spring caused by the movement of the spool is applied to the pressure-sensitive conductive element, and the position of the spool can be detected by detecting the change. Further, at this time, the pressure-sensitive conductive element can adjust the pressure applied to the pressure-sensitive conductive element due to the shift of the spool by the adjusting screw.

[0010]

FIG. 1 shows a first embodiment of the present invention. In the figure, the stack valve 1 is the same as the conventional structure, and the same parts are denoted by the same reference numerals and description thereof will be omitted. However, 23 and 24 are spool neutral position holding springs 2
2 shows a spring receiver mounted on a spool 3 for supporting the spool 2.

In the present invention, the position detecting device 30 of the spool 3 of the stack valve 1 is mainly composed of a pressure-sensitive conductive element inserted between one spring receiver 23 and the holding spring 22. However, the pressure-sensitive conductive element 30 is an element that changes the electric resistance by pressurization. The element is small when it is lightly touched, and changes its resistance continuously according to the strength of the pressing force when pressed strongly. .

As a result, the movement of the spool 3 presses the neutral holding spring 22, and the pressure can be detected as a change in the electric resistance of the pressure-sensitive conductive element. FIG. 2 shows an example of a change in electric resistance of the pressure-sensitive conductive element at this time. However, the pressure-sensitive conductive element used is an experimental example using an elastic pressure-sensitive conductive element mainly composed of a rubber material or an elastomer.

FIG. 3 shows a second embodiment. In the figure, a stack valve 1 is the same as that of the first embodiment, and the same components are denoted by the same reference numerals and description thereof will be omitted. However, 25 is a spring storage case for the neutral position holding spring 22.

According to the present invention, as the position detecting device 40 of the spool 3 of the stack valve 1, the spring storage case 2 is used.
5, an adjusting screw 41 is screwed into the pressure-sensitive conductive element 4 at its tip.
2, and a spring 43 is interposed between the tip of the spool 3 and the pressure-sensitive conductive element 42.

Thus, the shift of the spool 3 is applied to the pressure-sensitive conductive element 42 via the spring 43, and the shift of the spool 3 can be captured as a change in the electric resistance of the pressure-sensitive conductive element 42. At this time, the resistance value at the time of the neutral position of the spool 3, for example, can be easily adjusted to a predetermined value by the adjusting screw 41. Although a three-position center bypass type stack valve provided with a manual spool has been described as an embodiment, it is needless to say that this can be similarly applied to a two-position switching type stack valve.

[0016]

As described above, according to the present invention, the shift of the spool is measured from the change in its electrical resistance using a pressure-sensitive conductive element. This can be accurately detected.
Further, since the pressure-sensitive conductive element is small, the valve housing can be made compact. At this time, the pressure-sensitive conductive element is supported by an adjusting screw attached to an appropriate position of the stack valve housing, thereby having an effect that, for example, the value of the neutral position of the spool can be set to a predetermined value.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a first embodiment of the present invention.

FIG. 2 is a performance curve diagram of a pressure-sensitive conductive element used in the present invention.

FIG. 3 is a longitudinal sectional view of a second embodiment of the present invention.

FIG. 4 is a schematic explanatory view of a conventional stack valve spool position detecting device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Stack valve 2 Housing 3 Spool 22 Spool neutral position holding spring 30 Spool position detection device 40 Spool position detection device 41 Adjustment screw 42 Pressure sensitive conductive element 43 Spring

Claims (2)

[Claims] In a stack valve having a spool, a pressure-sensitive conductive element is mounted between a holding spring for holding the spool in a neutral position and the spool, and a change in pressure applied to the pressure-sensitive conductive element due to the movement of the spool is electrically controlled. A stack valve characterized in that the stack valve is automatically detected. 2. A stack valve having a manual spool, wherein a pressure-sensitive conductive element is attached to the spool via a spring, and the pressure-sensitive conductive element is supported by an adjusting screw attached to an appropriate position of the stack valve housing. A spool position detecting device for a stack valve, wherein a spring pressure applied to a pressure-sensitive conductive element is adjustable by a pressure sensor, and a change in pressure applied to the pressure-sensitive conductive element due to a shift of the spool is electrically detected.