JPH07220593A - Pressure switch - Google Patents

Abstract

PURPOSE:To provide stable and correct action even in the case where a microswitch of a small response is used by providing a response expanding spring for expanding the response of the micro-switch between the microswitch and an actuation member. CONSTITUTION:In a pressure switch, a response expanding spring 15 is provided between an upper end 41 of a shaft part 28 and a button 51 of a micro-switch 5. The response expanding spring 15 is compressed till necessary force to generate snap action of the micro-switch 5 is reached to pass an incomplete range of the microswitch speedily by force in a stroke direction accumulated in the response expanding spring 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention detects the pressure of a fluid.
ON-OFF pressure switch. In particular, the present invention relates to a pressure switch that is capable of adjusting a pressure difference to be turned on and off and that can perform an accurate operation even when a micro switch having a small hysteresis is used in a pressure switch such as a so-called differential pressure adjusting method.

[0002]

2. Description of the Related Art FIG. 3 is a schematic diagram showing the internal structure of a conventional pressure switch. In the housing 1, an operating member 3 which is basically in the form of a shaft is built in so as to be movable a little distance in the axial direction. The operating member 3 is composed of a piston 21, a flange 27 and a shaft portion 28 from the bottom of the drawing. The arm A37 and the arm B39 are fixed to the shaft portion 28.

The lower surface of the piston 21 is a pressure receiving surface that receives fluid pressure. The piston 21 moves up and down in the cylinder 23 according to the balance between the fluid pressure and the spring force applied to the entire operating member 3. A seal 25 is provided between the piston 21 and the cylinder 23 to prevent fluid pressure from entering the housing.

A flange 27 is in contact with the upper portion of the piston 21. The flange 27 can move vertically between the contact surface 29 fixed to the housing 1 and the end plate 31. However, the stroke is limited to S in the figure (the gap between the upper surface of the flange 27 and the lower surface of the end plate 31). When the fluid pressure is low, the operating member 3 is pressed downward by the operating pressure setting spring 7, so that the flange 27 is pressed against the contact surface 29. When the fluid pressure becomes higher than the set pressure (when the fluid pressure overcomes the compression force of the operating pressure setting spring 7),
The piston 21, the flange 27, and the like move upward, and finally, the upper surface of the flange 27 abuts the lower surface of the end plate 31, and the operating member 3 cannot move upward any further.

The shaft portion 3 is connected to the upper portion of the flange 27. The upper end 41 of the shaft portion 3 is in contact with the button 51 of the micro switch 5. This button 51 is for the shaft 3
Driven by the upper end 41 of the. The micro switch referred to in this specification means a small 0N-OFF switch. However, "small" means "to the extent that it can be used in a pressure switch", and the present invention is not limited thereby.

An arm A37 fixed to the shaft 28
And the operating pressure adjusting means 9 provided in the housing 1.
An operating pressure setting spring 7 is provided between and to urge the arm A downward. Operating pressure adjusting means 9
Is movable in the expansion / contraction direction of the operating pressure setting spring 7 with respect to the housing 1, and has an initial length (a value obtained by subtracting the initial compression length from the free length) of the operating pressure setting spring 7, and
Determine the initial compression force.

The other arm (arm B39) fixedly mounted on the shaft portion 28 faces the differential pressure pickup 47 with a gap of d in the moving direction of the operating member 3 (upper part of the figure). ing. The gap d can be adjusted by the differential pressure pickup adjusting means 48. When the arm B39 (operating member 3) is pushed by the fluid pressure and moves upward by d, the arm B39 contacts the differential pressure pickup 47.

In order to further raise the arm B39 from this state, it is necessary to push over the differential pressure adjusting spring 11.
That is, after this stage, the operating member 3 rises against both the operating pressure setting spring 7 and the differential pressure adjusting spring 11. The differential pressure adjusting means 13 determines the initial length of the differential pressure adjusting spring 11 and the initial compression force.

FIG. 4 is a graph showing the operating characteristics of the conventional pressure switch of FIG. The horizontal axis represents the working member stroke (also the microswitch piston stroke) and the vertical axis represents the fluid pressure. The thick, bent solid line ABCDE in the figure represents the operating characteristics of the pressure switch. It should be noted that, in the figure, the operation resistance force of the piston of the microswitch and the hysteresis due to friction of each part are neglected.

In the state of the origin 0 (pressure 0, stroke 0), as shown in FIG. 3, the operating member 3 receives the initial compressive force of the operating pressure setting spring 7 and the flange 27.
Is pressed against the contact surface 29. When the fluid pressure rises from here and the pushing force by the fluid pressure becomes equal to the initial compression force of the operating pressure setting spring 7, the line A
Is the U point at the upper end of.

When the fluid pressure further increases, the operating member gradually starts to stroke upward. The state at this time is the state of line B. The upward inclination of the line B represents the spring constant of the operating pressure setting spring 7. In the middle of the line B (at the time of pressure drop), there is a point V at which the microswitch is turned off.

When the operating member makes a stroke d for the differential pressure pickup, the arm B39 moves the differential pressure pickup 4
Hit 7. The characteristic point at this time is W. After this,
The differential pressure adjusting spring 11 also starts to work. First, as indicated by the line C, the stroke of the operating member is constant until the fluid pressure increases by the initial compression force of the differential pressure adjusting spring.
Next, the increase in the spring resistance force per stroke unit length of the operating member increases and enters the region of the tight line D of the slope of the characteristic line.
In the middle of the line D, there is a point Y at which the microswitch is turned on (when the pressure rises).

Further, when the fluid pressure rises and the operating member makes a stroke so that the flange 27 of the operating member comes into contact with the end plate 31 (stroke S), the operating member does not make a stroke even if the fluid pressure further rises. (Line E area).

The hysteresis stroke difference between the micro switch ON point (point Y) and the OFF point (point V) in the above-mentioned operation member stroke is the micro switch hysteresis. The fluid pressure difference between points Y and V is the operating pressure difference of the pressure switch. By adjusting the pickup adjusting means 48, the amount d of the differential pressure pickup can be adjusted. Moreover, the magnitude of the differential pressure can be adjusted by adjusting the initial compression force of the differential pressure adjusting spring.

Although not shown in the drawing, a toggle mechanism is provided in the micro switch, or a Belleville sprig (pecon, a leaf spring that reverses the pecon) is inserted between the flange 27 and the end plate 31, It has also been attempted to improve the hysteresis of operating characteristics and enhance the stability of pressure switch operation. Further, the differential pressure adjusting spring may be provided in the direction opposite to the direction in which the operating member 3 resists the fluid pressure.

[0016]

By the way, most microswitches in the general market have a hysteresis of 0.1 mm or less. It is extremely difficult to design, manufacture, and adjust the pressure switch so that the pickup point (point W in FIG. 4) for adjusting the differential pressure is placed in this small hysteresis of 0.1 mm. Even if the initial settings could be made, it was difficult to make stable settings for long-term use due to slight friction of parts and expansion / contraction of the mechanism due to temperature changes. As a countermeasure, there are many pressure switches in which a lever mechanism is inserted between the upper end 41 of the shaft portion of the operating member and the button 51 of the microswitch to expand the hysteresis of the microswitch to make the stroke hysteresis of the operating member. Alternatively, a long-hysteresis micro switch (hysteresis 0.3 mm to 0.4 mm) may be selected (or custom-made).

However, as a result of providing the above-mentioned lever mechanism, the mechanism of the pressure switch becomes complicated and large, and at the same time, there are many unstable elements for stable operation. In addition, when the long differential type micro switch is used, the micro switch that can be used is limited and the price of the micro switch is high.

An object of the present invention is to provide a pressure switch capable of stable and accurate operation even when a micro switch having a small hysteresis is used.

[0019]

In order to solve the above-mentioned problems, a pressure switch according to a first aspect of the present invention includes a housing, an operating member which is contained in the housing and operates by fluid pressure, and an operation of the operating member. ON-OFF driven by a micro switch, an operating pressure setting spring that urges the operating member in a direction that resists fluid pressure, and an operating pressure that engages the operating pressure setting spring and sets the operating start pressure of the operating member A pressure switch comprising adjusting means; the microswitch has a hysteresis stroke which is a hysteresis stroke in ON-OFF operation, and a hysteresis for expanding the hysteresis of the microswitch between the microswitch and the operating member. It is characterized in that an expansion spring is provided. The differential expansion spring may be directly provided between the micro switch and the operating member, but may be indirectly provided through some member. Also in the present invention, the provision of a lever (for converting force transmission direction, etc.) between the microswitch and the operating member is not excluded.

[0020]

[Operation] The spring constant of the differential expansion spring is K _a , the initial compression force is F _a , and the initial operation resistance of the micro switch button is R _p.
(R _p > F _a ), the resistance expansion coefficient (spring constant) of the micro switch button is K _p , the stroke of the operating member is S _a ,
The compression amount S _x when the micro switch is turned on and the stroke until the micro switch button is turned on are S _p . The relational expression of the balance of these forces when the micro switch is turned on is as follows. R _p + K _p S _p = F _a + K _a S _x (1) From this, the following is obtained. S _x = (R _p −F _a ) / K _a + S _p × K _p / K _a ... (2) The stroke S _{a of the} operating member is S _a = S _p + S _x , and is therefore S _a = S _p + S _x = (R _p −F _a ) / K _a + (1 + K _p / K _a ) S _p ··· (3) Here, K _a is smaller than K _p , for example, one half. If set to, then: S _a = (R _p −F _a ) / K _a + 3S _p ··· (4)

Here, if (R _p −F _a ) / K _a is considered to be _a constant (determined by design and adjustment), S _a can be obtained by multiplying S _p by 3 + α.
The relationship is expanded to. In this way, by selecting various characteristics of the differential expansion spring and the micro switch, the stroke of the micro switch button can be expanded to be the stroke of the operating member. Therefore, the hysteresis stroke, which is the hysteresis stroke of the microswitch, can also be the operation member hysteresis that has been expanded in the stroke stage of the operation member. For this reason, even when a micro switch having a small hysteresis is used, the hysteresis in the stroke of the operating member can be increased, so that a pressure switch capable of stable and accurate operation can be provided.

The pressure switch according to the second aspect of the present invention includes a housing, an operating member which is built in the housing and operates by fluid pressure, and is turned on by the operation of the operating member.
-A micro switch that is driven OFF, an operating pressure setting spring that urges the operating member in a direction that resists fluid pressure, and an operating pressure adjustment that engages with this operating pressure setting spring and sets the operating start pressure of the operating member And a elastic member is provided between the micro switch and the operating member.

The elastic member is a member having elasticity such as a spring (may be a differential expansion spring) or rubber. The operation of this elastic member will be described with reference to FIG. In the absence of the elastic member, the micro switch is pushed by the operating member and operates according to the stroke force curve of the micro switch of FIG. In the pressure switch, when the pressure changes at a slow speed, the operating member strokes at a slow speed, and therefore, it takes a long time to stroke the incompletely contacted area of the microswitch at a slow speed. And incomplete contact of microswitches is often a problem.

Due to the effect of the elastic member, when the micro switch is turned on, even if the operating member makes a stroke at a slight speed, the spring force built in the elastic member causes the imperfect region to pass through at once. When the micro switch is turned off, if there is no elastic member, the micro switch is restrained by the operating member and it is not possible to take a snap action.However, if an elastic member is attached, the micro switch snaps the action depending on the degree of freedom of the elastic member. Can be generated, and the problem associated with the incomplete contact area can be solved.

In the pressure switch of the present invention, further, after the operation of the operating member is started and after a predetermined pickup, the differential pressure adjusting spring for urging the operating member in the direction against the fluid pressure or in the opposite direction, and , The above pickup amount,
And / or having a differential pressure adjusting means for adjusting the initial compression force of the differential pressure adjusting spring, and adjusting the differential pressure between the fluid pressure when the microswitch is ON and the fluid pressure when it is OFF It can also be adjustable by means.

The differential pressure acting point at which the differential pressure adjusting spring begins to work is
It must be set within the hysteresis of the micro switch.
Even with a micro switch having a small hysteresis, since the hysteresis of the operating member is enlarged by the hysteresis expansion spring of the present invention, it becomes easy to set the differential pressure action point, and it is possible to operate stably for a long time. It is possible to provide a simple pressure switch having no complicated mechanism.

[0027]

EXAMPLES Examples of the present invention will be described below. Figure 1
It is the figure which expressed typically the structure of the pressure switch which concerns on one Example of this invention. Most of the structure of the pressure switch of FIG. 1 is the same as that of the pressure switch of FIG. In both figures, the same parts and portions are designated by the same reference numerals.

In the pressure switch of FIG. 1, a differential expansion spring 15 is provided between the upper end 41 of the shaft portion 28 and the button 51 of the micro switch 5. Only this point is different from the pressure switch of FIG. The action of the differential expansion spring 15 is as described above.

FIG. 2 is a sectional view showing the internal structure of a pressure switch according to another embodiment of the present invention. The basic mechanism of this pressure switch is the same as that of the pressure switch of FIG. 1 except for the Belleville spring 71.

In the pressure switch of FIG. 2, the housing is divided into upper and lower parts (a lower housing 1 and an upper housing 1 '). Both housings are firmly connected by bolts (not shown). In the housing,
The operation member 3 including the piston 21, the spring retainer 77, and the operation shaft 83 is built in from the bottom. The operating pressure setting spring 7 is coaxially arranged around the operation shaft 83. The micro switch 5 is driven by the operation of the spring retainer 77 via the differential expansion spring 15.

The operation member 3 around the piston 21 will be described. The piston 21 is slidably fitted in the cylinder 23 and the pressure port 61 in the vertical direction. Fluid pressure (hydraulic pressure or the like) is introduced into the inner hole 62 of the pressure port 61, and the fluid pressure is passed through the throttle 63 of the inner hole 62 and the piston 2
It is designed to cover the lower surface of 1. This fluid pressure is
It is sealed by a seal 25 (O ring, U packing, backup ring, etc.) interposed between the piston 21 and the inner surface of the pressure port upper hole 64. The cylinder 23 is for guiding the piston 21. The pressure port 61 is screwed to the housing 1.

The circumference of the spring retainer 77 will be described. The spring retainer 77 is in contact with the upper surface of the piston 21 at its lower end surface, and is driven upward by the piston. From the outer surface of the central portion of the spring retainer 77, the flange 2
7 is protruding in a ring shape. The inner peripheral upper surface of the Belleville spring 71 is in contact with the lower surface of the flange 27. The outer peripheral portion of the Belleville spring 71 is held in a Belleville spring retainer 73 (divided structure).

A fitting protrusion 81 at the lower end of the operating shaft 83 is firmly connected to a hole 78 in the central portion of the upper surface of the spring retainer 77 by a screw or the like. Further, the lower end portion of the operating pressure setting spring 7 is inserted into the concave portion 79 on the upper surface of the spring retainer 77. The outer periphery of the spring retainer 77 is a flange 27. The flange 27 can be stroked vertically (S in FIG. 1) between the upper surface of the Belleville spring retainer 73 and the end plate 31 integral with the upper housing 1 ′. Flange 2
The action of 7 is the same as that of the flange of FIG.

Around the operating pressure setting spring 7 will be described. As described above, the lower end of the operating pressure setting spring 7 enters the upper surface recess 79 of the spring retainer 77. The upper end of the operating pressure setting spring 7 is pressed by a spring presser 84. Both ends of the spring retainer 84 are protruded from the window 82 of the housing 1 ′ and are retained by a nut 85 screwed to a male screw 86 on the outer surface of the upper cylinder of the upper housing 1. The male screw 86, the nut 85, and the spring retainer 84 form the operating pressure adjusting means 9. By adjusting the vertical position of the nut 85, the initial compression force of the operating pressure setting spring 7 can be adjusted.

The differential pressure adjusting mechanism 91 will be described. The differential pressure adjusting mechanism 91 is provided at the top of the pressure switch in FIG. The outer periphery of the upper end 89 of the operating shaft is guided by a ring-shaped operating shaft guide 87 fitted into the inner surface of the housing 1 '. The operation shaft upper end 89 faces the lower end surface of the differential pressure pickup adjusting means 48 with a slight gap (corresponding to d in FIG. 1). The means 48 is a small screw rod and is screwed into the central portion of the spring receiver 93. This screw rod has a cross groove or the like cut on the upper end surface so that it can be turned by a screwdriver.

The differential pressure adjusting spring 11 has the above-mentioned spring receiver 93.
And the spring retainer 95. The spring retainer 95 has a male thread on the outer peripheral surface, and is screwed with a female thread 94 cut on the inner surface of the upper surface of the housing 1 '. A driver groove 96 is cut on the upper surface of the spring retainer 95. By adjusting the screwing position of the spring retainer 95, the differential pressure adjusting spring 11
The initial compression force of can be adjusted.

The vicinity of the micro switch 5 will be described. In the pressure switch of FIG. 2, the micro switch 5 is arranged in parallel with the operation shaft 83 so as to detect the movement of the flange 27 of the spring retainer 77. A differential expansion spring 15 is provided between the button 51 of the micro switch 5 and the flange 27. In the pressure switch of FIG. 2, the piston 21, the spring retainer 77, and the operating shaft 83 are integrally operated to operate the operating member 3
Is formed, the flange 27 of the spring retainer 77 is formed.
The position of the operating member 3 can be detected by detecting the position of.

The action of the differential expansion spring 15 is the same as that of the differential expansion spring shown in FIG. It should be noted that, in FIGS. 1, 2, and 3, parts and portions denoted by the same reference numerals basically have the same operation.
The pressure switch in Fig. 2 uses a micro switch with a hysteresis of 0.06 mm to measure the stroke of the operating shaft.
I was able to magnify it to 0.3mm, 5 times. It is relatively easy to increase the hysteresis by 2-3 times in a limited space, but in order to obtain 5 times the magnification with the conventional technology, a complicated mechanism such as a two-stage lever is required. Met. In the present invention, the hysteresis can be expanded at a high magnification with a simple mechanism.

Generally, the micro switch has a built-in toggle spring mechanism, etc.
When the push button of the micro switch is stroked at a fine speed, incomplete contact often occurs in the vicinity of the snap action. In the present invention, the hysteresis expansion spring compresses until the force necessary for the microswitch to generate the snap action is reached, and the force in the stroke direction stored in the hysteresis expansion spring causes the incomplete area of the microswitch to be suddenly changed. Can pass through. If the micro switch strokes back, assuming there is no hysteresis expansion spring,
Since the micro switch is restrained by the operation axis, even if the micro switch enters the area where the snap action occurs, the micro switch follows the operation axis and makes a slow motion. However, since the differential expansion spring is added, the differential expansion spring is compressed by the force of the snap action of the micro switch, so that the micro switch can be operated by the snap action and the incomplete area is eliminated. As another means for eliminating the incomplete area of the microswitch, there is a method using a Belleville spring or the like. However, the method of this embodiment is characterized in that both the expansion of the hysteresis of the microswitch and the elimination of the incomplete area are simultaneously solved by one means.

[0040]

As is apparent from the above description, the present invention exhibits the following effects. Even if a micro switch having a small hysteresis is used, it is possible to provide a pressure switch that operates accurately and stably. By selecting the spring constant of the hysteresis expansion spring, the magnification of the hysteresis of the microswitch can be arbitrarily selected.

The differential expansion spring is smaller, cheaper, and more reliable than the lever function. Since the differential expansion spring plays a role of a cushioning member, there is no possibility of pushing the push button (piston) of the micro switch too much, and an excessive pushing force to the micro switch does not occur. Therefore, the micro switch can be protected. By the elastic member, the incomplete contact area of the micro switch can be passed at once, and the incomplete contact is eliminated.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing the configuration of a pressure switch according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing the internal structure of a pressure switch according to another embodiment of the present invention.

FIG. 3 is a diagram schematically showing the internal structure of a conventional pressure switch.

FIG. 4 is a graph showing operating characteristics of the pressure switch of FIG.

FIG. 5 is a diagram illustrating the operation of the elastic member according to the present invention.

[Explanation of symbols]

1 Housing 3 Working Member 5 Micro Switch 7 Working Pressure Setting Spring 9 Working Pressure Adjusting Means 11 Differential Pressure Adjusting Spring 13 Differential Pressure Adjusting Means 15 Hysteresis Enlarging Spring 21 Piston 23 Cylinder 25 Seal 27 Flange 28 Shaft 29 Abutting Surface 31 End Plate 37 Arm A 39 Arm B 41 Shaft Upper End 45 Abutment 47 Differential Pressure Pickup 48 Pickup Adjusting Means 51 Micro Switch Button

Claims (3)

[Claims] 1. A housing, an operating member which is housed in the housing and operates by fluid pressure, a microswitch which is turned on and off by the operation of the operating member, and an operating member which is mounted in a direction against the fluid pressure. A pressure switch comprising an urging operation pressure setting spring and an operation pressure adjusting means which engages with the operation pressure setting spring and sets an operation starting pressure of an operation member; The pressure switch having a hysteresis which is a hysteresis stroke in, and a hysteresis expanding spring for expanding the hysteresis of the microswitch is provided between the microswitch and the operating member. 2. A housing, an operating member which is housed in the housing and operates by fluid pressure, a microswitch which is turned on and off by the operation of the operating member, and an operating member which is attached in a direction against the fluid pressure. A pressure switch comprising: a biasing operating pressure setting spring; and an operating pressure adjusting means that engages with this operating pressure setting spring and sets an operating start pressure of the operating member; between the microswitch and the operating member. ,
A pressure switch comprising an elastic member. 3. A differential pressure adjusting spring for urging the operating member in a direction against the fluid pressure or in the opposite direction after a predetermined pickup after the operation of the operating member is started, and the pickup amount and And / or has a differential pressure adjusting means for adjusting the initial compression force of the differential pressure adjusting spring, and the differential pressure between the fluid pressure when the micro switch is ON operation and the fluid pressure when it is OFF operation is A pressure switch according to claim 1 or 2, which is adjustable by means of: