KR101151343B1 - Pressure sensor - Google Patents

Abstract

The present invention relates to a sensor for measuring pressure using a fluid. The pressure sensor includes a diaphragm, a cylinder member extending downward along a circumference of the diaphragm, a piston member disposed to be spaced apart from the diaphragm inside the cylinder member, a working fluid accommodated between the diaphragm and the piston member, and the cylinder. An elastic member provided between the member and the piston member, an elastic membrane for sealing between the cylinder member and the piston member, and a storage fluid accommodated in a space enclosed by the elastic membrane, and upwardly to the piston member. When a load is applied, the load is transmitted to the diaphragm through the working fluid as a pressure, and by the pressure a portion of the working fluid is moved to the storage fluid while the piston member is moved upward and the elastic member is deformed. And the load applied to the piston member When removed, part of the storage fluid is moved to the working fluid and the piston member is moved downward by the pressure generated while the deformed elastic member is recovered. According to the present invention, even if the pressure sensor is small in size, a large load can be measured, and the loss of the fluid can be prevented due to the breakage of the part accommodating the fluid. There is no need to use other external systems.

Description

Pressure sensor

The present invention relates to a sensor for measuring pressure using a fluid.

Conventionally, sensors for measuring pressure include a load cell, a force sensing resistor (FSR), a piezoelectric element, and the like.

A load cell is a device that attaches a strain gage to a precisely shaped member to measure weight or force from deformation of a specific part. Here, the strain gauge is a kind of resistance, for example, a strain measuring device using a property that the very thin metal wire is reciprocated several times in the measurement direction, the cross-sectional area decreases and the resistance increases as the length increases. Basically, a tension-compression load cell that measures the amount of change in resistance by attaching a strain gauge in the longitudinal direction to the member, and makes a structure having a portion to be compressed and a portion to be stretched, and attaches a strain gauge to each portion, and a Wheatstone bridge circuit Bending / shear type load cell constituting the.

Among these, the tension-compression load cell has a large error when measuring load. In addition, the bent / shear type load cell has a disadvantage in that the size of the hardware is larger than the measurement weight. In particular, when a load cell is used in the foot of a robot, the force can be concentrated at a point, so that sufficient force can be measured for each part of the foot. Bending / shear load cells are small in size (for example, 2000 N). There is a problem that it is difficult to measure each part separately because it cannot be measured.

In addition, Force Sensing Resistors (FSRs) are pressure sensors whose resistance decreases as pressure increases. There is a second layer above the first layer with both electrodes creating an empty space and a third layer of resistive material, so that when pressure is applied, the third layer meets the first layer and starts to conduct electricity, and the pressure increases. As the area of contact of the resistive material increases, the total resistance decreases.

Such FSR has a threshold value due to the device gap, a difference in pressure measurement occurs depending on the pressed part or shape, and thus the reproducibility is inferior. In the case of a large force, the measurement accuracy is remarkably inferior. Usually around 10 kg is the available limit. In addition, the thin film structure has a disadvantage in that it is easy to be torn, although the applicable area is varied.

Piezoelectric elements (piezoelectric element) is a pressure sensor that uses a property that the potential difference between the two sides when the pressure is applied to a special crystal plate to generate electricity, and because the electromotive force per plate is small, several plates are connected in series.

However, such piezoelectric elements have a problem that the price is expensive, there is noise, and only the dynamic load change is detected so that the force acting as a stationary state is not recognized.

The present invention has been created to solve the problems described above, the problem to be solved by the present invention can be stably measured a large force, such as the force acted by the foot of the foot walking robot through a small scale device To provide a pressure sensor.

Pressure sensor according to an embodiment of the present invention for achieving the above object is a diaphragm, a cylinder member extending downward along the circumference of the diaphragm, a piston member spaced apart from the diaphragm inside the cylinder member, the A working fluid accommodated between the diaphragm and the piston member, an elastic member provided between the cylinder member and the piston member, an elastic membrane sealing the cylinder member and the piston member, and a space enclosed by the elastic membrane. A storage fluid is received, and when a load is applied upwardly to the piston member, the load is transmitted to the diaphragm through the working fluid at a pressure, and the pressure causes a portion of the working fluid to move to the storage fluid. While the piston member is moved upward and the bullet And member is deformed, when a load is applied to the piston member removed, by the pressure generated as the modified elastomeric member to recover a portion of the stored fluid is moved to the working fluid the piston member is moved downwardly.

The cylinder member includes a first cylinder member extending downward along the circumference of the diaphragm and having a limiting jaw formed along a lower circumference of the inner side, and a second cylinder member connected downward with respect to the first cylinder member. In addition, the working fluid may be disposed inside the first cylinder member to be in contact with the bottom surface of the diaphragm.

The piston member is a load transfer portion inserted into the inner side of the first cylinder member to abut the lower end of the working fluid, an elastic support portion connected to the load transfer portion and the support jaw is formed along the circumference of the lower side of the outer surface, and It may include a load input unit connected to the elastic support and receiving a load through the lower end.

The load transfer part is provided along the circumference of the upper side of the outer side and is provided along the circumference of the outer side of the limiting projection, the limiting projection located on the upper side of the limiting projection to the circumference of the inner surface of the first cylinder member It may include a fluid supply hole penetrating the outer surface and the top, and a valve that opens when the negative pressure acts upward from the fluid supply hole and closes when a positive pressure acts downward toward the fluid supply hole.

The elastic member may be installed between the limiting jaw and the support jaw so that the piston member elastically moves up and down.

The elastic membrane may connect the circumference of the inner surface of the second cylinder member and the circumference of the outer surface of the elastic support in a sealed state.

The storage fluid may be disposed in a space surrounded by the load transfer part, the first cylinder member, the second cylinder member, the elastic support part, and the elastic membrane.

The second cylinder member may include an extension part extending in an outward direction along a circumference at a lower end of the first cylinder member, and a cylinder part extending downward in a circumference from an end in the outward direction of the extension part.

The cylinder portion includes a cylinder protrusion for forming a cylinder groove into which one end of the elastic membrane is inserted along the circumference of the inner side, and the support jaw includes a support jaw groove formed along the circumference of the outer side such that the other end of the elastic membrane is inserted. It may include.

The positive pressure may occur when the load is input to the load input unit, and the negative pressure may occur when the elastic restoring force of the elastic member that is elastically compressed after the input of the load to the load input unit is applied to the piston member. have.

The working fluid may be included as part of the storage fluid by moving a portion between the ring and the circumference of the inner surface of the first cylinder member when the positive pressure is applied.

The storage fluid may be included as part of the working fluid by moving a portion through the fluid supply hole when the negative pressure is applied.

The limiting protrusion may contact a lower end of the limiting jaw before the load is input.

The load input unit may have a shape in which a circumference of an outer surface is engaged with a circumference of an inner surface of the second cylinder member.

The working fluid and the storage fluid may be incompressible.

A strain gauge may be attached to the diaphragm.

According to the present invention, the load can be transmitted from the piston member to the diaphragm through the fluid surrounded by the cylinder member, so that even if the pressure sensor is small, large load can be measured. For example, the pressure sensor can be integrated into the foot of a foot walking robot.

In addition, since the load is transmitted not only through the mechanical structure but evenly through the fluid pressure, the unbalanced force and impact can be stably transmitted to measure the pressure.

And since the strain of the diaphragm is measured, by changing the material and thickness of the diaphragm, as long as the pressure sensor itself is not destroyed, very high weight can be measured.

In addition, by including the composition of the storage fluid, the elastic membrane, the valve, and the elastic member to interact with the working fluid, it is possible to prevent the loss of the fluid due to the breakage of the portion containing the fluid and to compensate for the loss of the fluid. There is no need to use other external systems.

1 is a three-dimensional view schematically showing a cross section of a pressure sensor according to an embodiment of the present invention.
2 is a plan view of one embodiment of a strain gauge.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a three-dimensional view schematically showing a cross section of a pressure sensor according to an embodiment of the present invention. In the description of the pressure sensor 100, terms related to directions such as up, down, top, bottom, top, bottom, top, bottom, and the like are based on the pressure sensor 100 according to one embodiment of the present invention shown in the drawings. I did it. However, in various applications of the present pressure sensor 100, the pressure sensor as seen in accordance with the direction of action of the load 200 and the resulting pressure measurement direction such that the upper end is disposed downward or the up and down direction toward the left and right direction ( 100 may be arranged in various directions.

Looking at the configuration of the pressure sensor 100 with reference to Figure 1, the pressure sensor 100 according to an embodiment of the present invention is the diaphragm 1, the diaphragm 1 is attached to the strain gauge 11 Cylinder members 2 and 3 extending downward along the circumference, piston members 4 spaced downward from the diaphragm 1 inside the cylinder members 2 and 3, the diaphragm 1 and the piston member ( 4) an elastic member 5, a cylinder member 2, 3 and a piston member 4, which are installed in an up-down direction between the working fluid 7 accommodated therebetween, the cylinder members 2, 3 and the piston member 4; An elastic membrane (6) sealing between the (), and the storage fluid (8) accommodated in the space sealed by the elastic membrane (6).

Next, the operation of the pressure sensor 100 in accordance with the above-described configuration is outlined.

When the load 200 is applied upward to the piston member 4 in the pressure sensor 100, the load 200 is transmitted to the diaphragm 1 through the working fluid 7 as a pressure. A portion of the working fluid 7 is moved to the storage fluid 8 while the piston member 4 is moved upward and the elastic member 5 is deformed. When the load 200 applied to the piston member 4 is removed, a part of the storage fluid 8 is moved to the working fluid 7 by the pressure generated while the deformed elastic member 5 is recovered. (4) is moved downward.

Hereinafter, the action and effect after salping each configuration of the pressure sensor 100 in more detail.

Referring to FIG. 1, a pressure sensor 100 according to an embodiment of the present invention includes a diaphragm 1, cylinder members 2 and 3, a working fluid 7, a piston member 4, and an elastic member 5. , An elastic membrane 6, and a storage fluid 8.

First, the structure of the diaphragm 1 is examined.

The diaphragm 1 is a portion that receives an equal pressure from the fluid portion 3 to be described later and causes a predetermined elastic deformation upward. The material or thickness of the diaphragm 1 is preferably determined in consideration of the load 200 acting on the portion applied to the pressure sensor 100 so that the deformation generated is not excessive or too small.

The diaphragm 1 is attached with a strain gauge 11 capable of measuring the deformation caused by the diaphragm 1 under pressure. For example, as shown in FIG. 1, a strain gauge 11 may be attached to an upper surface of the diaphragm 1.

2 is a plan view of one embodiment of a strain gauge.

Referring to FIG. 2, the structure of the strain gauge 11 is exemplarily illustrated. The strain gauge 11 includes two radial strain gauges near the periphery, two circumferential strain gauges near the center, and a total of four small strain gauges. Since only one strain gauge 11 is installed, it may be configured to facilitate the Wheatstone bridge configuration.

Next, the structure of the cylinder members 2 and 3 is examined. The cylinder members 2, 3 comprise a first cylinder member 2 and a second cylinder member 3.

First, the first cylinder member 2 is connected to the diaphragm 1 and is a portion for receiving the working fluid 7 inside. In addition, the first cylinder member 2 also accommodates the upper portion of the load transfer portion 41 of the piston member 4 to receive the working fluid 7 therein.

Referring to FIG. 1, the first cylinder member 2 extends downward along the circumference of the diaphragm 1. Through this shape, the first cylinder member 2 wraps around the working fluid 7. This allows the working fluid 7 to transmit pressure only to a certain area portion of the diaphragm 1.

In addition, the first cylinder member 2 is formed with a limiting jaw 21 along the circumference of the lower side of the inner surface. The limiting jaw 21 may serve to restrict the upper portion of the load transmission part 41 of the piston member 4 to be described later from moving downward. In addition, the limiting jaw 21 may be a portion in which the upper end of the elastic member 5 to be described later is supported. Although the upper end of the elastic member 5 may be supported by the protruding portion of the limiting jaw 21, as shown in FIG. The top of can be supported.

The upper end of the first cylinder member 2 is preferably fixedly connected or integrated with the circumference of the diaphragm 1. By fixing the circumferential portion of the diaphragm 1 to the upper end of the first cylinder member 2, the center portion of the diaphragm 1 relative to the toollet portion of the diaphragm 1 when the load 200 is applied is applied. This is to allow elastic deformation to occur and to measure pressure therethrough.

In this case, the strain gauge 11 attached to the upper surface of the diaphragm 1 may be disposed in the same size at a position overlapping the circumference of the inner surface of the first cylinder member 2 in the vertical direction. The strain gauge 11 applies a pressure to the diaphragm 1 and pushes the diaphragm 1 upward according to the load 200 on which the working fluid 7 disposed in the circumference of the inner surface of the first cylinder member 2 is applied. It is to measure the deformation occurring in 1). Therefore, the strain gauge 11 is formed to have the same size as the circumference of the inner surface of the first cylinder member 2, which is the size to which pressure is applied to the diaphragm 1. It may be efficient to be disposed at a position overlapped with the portion of the circumference of the inner side in the vertical direction. For reference, the strain gauge 11 may be configured by measuring the tensile strain on the outer side and the tensile strain on the center side and calculating the pressure according to the difference.

In addition, although not shown in the drawing, the strain gauge 11 may be disposed in a groove formed in the diaphragm 1 in a predetermined size and depth. By being disposed in the groove, when the upper end of the pressure sensor 100 is attached to the lower end of the object to measure the pressure, the strain gauge 11 may not interfere with the lower end of the object to measure the pressure, the strain gauge 11 ) Can be prevented and thus accurate pressure measurements can be made. Alternatively, as another embodiment, the strain gauge 11 may be protected by surrounding the diaphragm 1 such that the first cylinder member 2 has an upper end formed higher than the strain gauge 11.

And the second cylinder member 3 is connected downward with respect to the first cylinder member 2. If the first cylinder member 2 is a portion for receiving the working fluid 7 inside, the second cylinder member 3 has an elastic member 5 with respect to the first cylinder member 2 and the piston member 4. It may be said that the storage fluid 8 is accommodated through the elastic membrane 6.

For example, referring to FIG. 1, the second cylinder member 3 extends in the outward direction along the circumference at the lower end of the first cylinder member 2, and the outward direction of the extension 31. It may include a cylinder portion 32 extending downward along the circumference from the end of. In order to accommodate the storage fluid 8 inside through the elastic membrane 6, it is preferable to include an extension 31 so as to have a larger width than the first cylinder member 2. However, the expansion part 31 is not necessarily required, and according to the amount of the storage fluid 8 or the arrangement of the elastic membrane 6, the second cylinder member 3 has the same width as that of the first cylinder member 4. It may be formed.

Also illustratively referring to FIG. 1, the cylinder portion 32 of the second cylinder member 3 forms a cylinder groove 321 into which one end 61 of the elastic membrane 6 is inserted along the circumference thereof. A cylinder protrusion 322 may be included. One end 61 of the elastic membrane 6 to be described later may be inserted into and fixed to the cylinder groove 321. For reference, the other end 62 of the elastic membrane 6 may be inserted and fixed in the support jaw groove 4211 formed in the support jaw 421 of the elastic support 42 of the piston member 4 to be described later.

In the embodiment shown in FIG. 1, a cylinder groove 321 is formed in the gap between the cylinder protrusion 322 and the expansion part 31. However, in addition to this form, the cylinder groove 321 may be implemented in various forms. For example, the cylinder groove 321 may be formed in the inner surface of the cylinder portion 32 itself, or may be formed as a groove in the center of the cylinder protrusion 322.

In addition, the cylinder groove 321 may be formed in various shapes that can more securely fix or grip one end 61 of the elastic membrane (6). For example, a small protrusion may be repeatedly formed in the cylinder groove 321 to maximize friction or adhesion, and an additional groove may be formed in which a predetermined protrusion formed at one end 61 of the elastic membrane 6 may be accommodated. have.

Next, the structure of the working fluid 7 is examined.

The working fluid 7 serves to transfer the load 200 transmitted from the piston member 4 to the lower surface of the diaphragm 1 at an equal pressure, so that the first cylinder member is brought into contact with the lower surface of the diaphragm 1. It is arrange | positioned inside (2). Since the working fluid 7 is surrounded by the first cylinder member 2, it is possible to transmit the load 200 acting while maintaining a constant shape to the diaphragm 1 at equal pressure.

And the working fluid 7 may be incompressible. The load 200 can be transmitted to the diaphragm 1 more accurately through the incompressible working fluid 7.

Next, the structure of the piston member 4 is examined.

The piston member 4 is a part which receives the load 200 and transmits it to the working fluid 7. Referring to FIG. 1, the piston member 4 includes a load input portion 43, an elastic support portion 42, and a load transfer portion 41.

First, the load input unit 43 is connected to the elastic support 42 and receives the load 200 through the lower end. Referring to FIG. 1, the load input unit 43 may have a shape in which a circumference of an outer surface is engaged with a circumference of an inner surface of the second cylinder member 3. As such, the load input unit 43 is formed to be engaged with the second cylinder member 3, thereby stably along the inner surface of the second cylinder member 3 even when a large load 200 is applied to the load input unit 43. As the load input unit 43 is moved, the load 200 may be transmitted to the working fluid 7.

In addition, although not shown in the drawing, the load input unit 43 may have a portion protruding in the horizontal direction spaced apart from the lower end of the second cylinder member 3 by a predetermined interval before the load 200 is input. When the load 200 or more than the maximum allowable amount is input, the horizontally protruding portion is configured to abut the lower end of the second cylinder member 3 so that no further load 200 is transmitted to the working fluid 7. To prevent it. Through such a configuration, the diaphragm 1 and the first cylinder member 2 can be prevented in advance.

In addition, the elastic support 42 is connected to the load transmission portion 41 and the support jaw 421 is formed along the circumference of the lower side of the outer surface. The elastic support 42 may serve to support the lower end of the elastic member 5 to be described later through the support jaw 421. The upper end of the elastic member 5 is supported by the lower end of the limiting jaw 21 of the first cylinder member 2 and the lower end of the elastic member 5 is supported by the support jaw 421, whereby the piston member 4 The first cylinder member 2 can be elastically behaved.

In addition, the support jaw 421 may include a support jaw groove 4211 formed along the periphery of the outer surface to insert the other end 62 of the elastic membrane 6. The other end 62 of the elastic membrane 6 to be described later may be inserted into and fixed to the support jaw groove 4211. Like the cylinder groove 321 of the cylinder portion 32 of the salping second cylinder member 3, the support jaw groove 4211 may also be implemented in various forms different from the embodiment shown in FIG. In addition, the support jaw groove 4211 may be formed in various shapes to more securely fix or grip the other end 62 of the elastic membrane 6, like the cylinder groove 321 described above.

The load transfer part 41 is inserted inside the first cylinder member 2 so as to contact the lower end of the working fluid 7. For example, referring to FIG. 1, the load transfer part 41 is not entirely inserted inside the first cylinder member 2, but only the upper portion thereof is above the limiting jaw 21 of the first cylinder member 2. It can be inserted into.

Referring to FIG. 1, the load transfer unit 41 includes a limiting protrusion 411, a ring 412, a fluid supply hole 413, and a valve 414.

As shown in FIG. 1, the limiting protrusion 411 is provided along the upper circumference of the outer side and is positioned above the limiting jaw 21 of the first cylinder member 2. In addition, the limiting protrusion 411 may be in contact with the upper end of the limiting jaw 21 before the load 200 is input. Before the load 200 is input, since the elastic member 5 to be described below pushes the support jaw 421 of the elastic support 42 of the piston member 4 downward, the limiting protrusion 411 is also moved downward. It may be in contact with the upper end of the limiting jaw (21).

1, the ring 412 is provided along the circumference of the outer surface of the restricting protrusion 411 to abut the circumference of the inner surface of the first cylinder member 2. For example, the ring 412 may be fitted into a ring groove 4111 formed along a circumference of the outer surface of the restricting protrusion 411. The working fluid 7 accommodated on the upper side of the load transfer part 41 through the ring 412 may be separated from the storage fluid 8. However, the ring 412 may not be completely sealed between the ring 412 and the inner surface of the first cylinder member 2. The pressure sensor 100 uses this point, and when a load 200 is applied, a part of the working fluid 7 passes between the ring 412 and the inner surface of the first cylinder member 2, and thus, the storage fluid ( 8) to go out, which will be described later in more detail.

1, the fluid supply hole 413 penetrates through an outer surface and an upper end of the load transmission part 41. For example, as shown in FIG. 1, the fluid supply hole 413 is a hole passing through two of two sides of the outer surface which is in contact with the storage fluid 8 of the load transfer part 41 and the load transfer part from the center of the hole. It may be formed in the form of a hole penetrating the upper end of the (41).

In addition, the valve 414 opens when the negative pressure acts upward from the fluid supply hole 413 and closes when the positive pressure acts downward toward the fluid supply hole 413. That is, the valve 414 is opened only in one of the up and down directions, and the opening direction is upward in the embodiment of FIG. 1.

Some of the storage fluid 8 may be moved toward the working fluid 7 through the fluid supply hole 413. On the contrary, some of the working fluid 7 may not be moved toward the storage fluid 8 through the fluid supply hole 413. This is because the valve 414 is provided to selectively open only when pressure is applied from the storage fluid 8 toward the working fluid 7 as described above.

In this case, the positive pressure may occur when the load 200 is input to the load input unit 43. In connection with the valve 414, when the load 200 is applied to the load input unit 43, the working fluid 7 is compressed and pushes the valve 414 downward in response to the valve 414. It cannot be opened upwards.

In addition, the negative pressure may occur when the elastic restoring force of the elastic member 5 which is elastically compressed after the input of the load 200 to the load input unit 43 is applied to the piston member 4. In relation to the valve 414, after the load 200 is applied to the load input section 43, the elastic member 5 to be described later pushes the support jaw 421 of the elastic support section 42 downward to load the load. The transfer part 41 is also moved downward until the limiting protrusion 411 reaches the limiting jaw 21 of the first cylinder member 2, whereby the working fluid 7 is tensioned and the valve 414 in response thereto. ), The valve 414 naturally opens upward.

That is, the reference for determining the positive pressure and the negative pressure may be regarded as a positive pressure when the working fluid 7 is compressed, and a case where the tension is reversed as a negative pressure.

However, since the valve 414 is opened only when a negative pressure is applied to the working fluid 7, movement from the working fluid 7 to the storage fluid 8 may occur through the fluid supply hole 413 and the valve 414. Only movement from the storage fluid 8 to the working fluid 7 takes place. That is, when the negative pressure acts on the storage fluid 8, a part of the storage fluid 8 may be moved through the fluid supply hole 413 to be included as part of the working fluid 7.

As such, the movement of the working fluid 7 from the working fluid 7 to the storage fluid 8 through the fluid supply hole 413 and the valve 414 is performed by the ring 412 and the first cylinder member when positive pressure is applied to the working fluid 7. It can be made through between the perimeters of the inner side of (2). That is, the working fluid 7 may be included as a part of the storage fluid 8 by moving a portion between the circumference of the inner surface of the ring 412 and the first cylinder member 2 when positive pressure is applied.

Next, the structure of the elastic member 5 is examined.

Referring to FIG. 1, the elastic member 5 is installed between the limiting jaw 21 and the supporting jaw 421 such that the piston member 4 elastically moves up and down. For example, the elastic member 5 may be a spring device, and disposed to surround the outer surface of the load transmission part 41 of the piston member 4 from the upper end of the elastic support 42 as shown in FIG. 1. Can be. In this case, the elastic member 5 may be disposed inside the elastic membrane 6, that is, in the space in which the storage fluid 8 is accommodated.

Alternatively, as another embodiment of the elastic member 5, the elastic member 5 may be disposed outside of the elastic membrane 6, that is, outside of the space in which the storage fluid 8 is accommodated. For example, as seen in FIG. 1, the cylinder protrusion 322 may be installed between the lower end of the cylinder protrusion 322 and the upper end of the load input unit 43. Through such an embodiment, the piston member 4 can also elastically move up and down with respect to the first cylinder member 2 and the second cylinder member 3.

In addition, the elastic member 5 may be variously disposed at an appropriate position capable of elastically moving up and down with respect to the first cylinder member 2 and the second cylinder member 3.

Through the elastic member 5, the piston member 4 may be elastically restored to a state before receiving the action of the load 200 after receiving the action of the load 200. In addition, the fluid that has been moved from the working fluid 7 to the storage fluid 8 may be moved back to the working fluid 8 through this recovery process. In addition, since the moving range of the piston member 4 is within a very limited range, the elastic recovery force of the elastic member 5 can be kept constant and almost unchanged.

Next, the structure of the elastic membrane 6 is examined.

As shown in FIG. 1, the elastic membrane 6 connects the circumference of the inner surface of the second cylinder member 3 and the circumference of the outer surface of the elastic support portion 42 in a sealed state. The storage fluid 8 may be accommodated inside the second cylinder member 3 without flowing out through the elastic membrane 6.

In addition, the elastic membrane 6 may be elastically increased according to the pressure. For example, when a positive pressure is applied to the working fluid 7 and a part of the working fluid 7 is moved to the storage fluid 8, the volume of the storage fluid 8 mainly composed of incompressible fluid increases, so that the elastic membrane (6) can also increase. On the contrary, when a negative pressure is applied to the working fluid 7 so that a part of the storage fluid 8 is returned to the working fluid 7 again, the volume of the storage fluid 8 is reduced, so that the elastic membrane 6 that has been expanded accordingly is Can be reduced.

Since the elastic membrane 6 has one end 61 connected to the second cylinder member 3 and the other end to the piston member 4, the piston member 4 is moved upward and downward relative to the second cylinder member 3. In consideration of being moved to, it is preferable not to be provided too taut. For example, as shown in FIG. 1, the elastic membrane 6 may be provided in a slightly wrinkled form, such as an English letter S or a jet Z. However, when a negative pressure is generated in the working fluid 7, when the part of the storage fluid 8 is moved back to the working fluid 7, it is not preferable to arrange the elastic membrane 6 so that the elasticity is too low. That is, the elastic membrane 6 may be provided to the extent that the elasticity of the piston member 4 may be covered while maintaining a certain degree of elasticity. In addition, the elastic membrane 6 may be a rubber material capable of a predetermined elastic behavior.

Next, the structure of the storage fluid 8 is examined.

The storage fluid 8 is disposed in a space surrounded by the load transmitting portion 41, the first cylinder member 2, the second cylinder member 3, the elastic support portion 42, and the elastic membrane 6. The storage fluid 8 receives the load 200 when the pressure fluid 100 is applied to the pressure sensor 100 when a part of the working fluid 7 leaks out between the ring 412 and the inner surface of the first cylinder member 2. Play a role. Since the working fluid 7 leaked out by the strong positive pressure is included as part of the storage fluid 8 accommodated in the space where the large pressure is not applied by the elastic membrane 6, the risk of external leakage of the fluid can be prevented. Can be. This storage fluid 8 may be incompressible, like the working fluid 7.

Hereinafter, the operation and effects of the pressure sensor 100 will be described.

First, looking at the pressure measuring mechanism through the pressure sensor 100, when a predetermined load 200 acts on the lower end of the load input portion 43 of the piston member 4, the load 200 is elastic at the load input portion 43 It is transmitted to the support part 42 and the load transmission part 41.

The load 200 transmitted to the load transfer part 41 compresses the working fluid 7 disposed inside the first cylinder member 2 to generate pressure. The pressure generated at this time presses the diaphragm 1 fixed to the first cylinder member 2 upward. The pressured diaphragm 1 is convexly finely deformed upward, and the strain is measured by the strain gauge 11 attached to the upper surface of the diaphragm 1. For example, in the case of the strain gauge 11 as shown in Figure 2 can measure the strain on the center side and the circumferential side can output the pressure applied to the diaphragm (1) through the difference in the tensile ratio of both sides.

Next, in the pressure measuring mechanism through the salping bone pressure sensor 100, the mechanism in which the fluid moves between the working fluid 7 and the storage fluid 8 in accordance with the action of the load 200 is examined.

When the load 200 is applied to the lower end of the load input portion 43 of the piston member 4, the piston member 4 transmits the load 200 to the working fluid 7, the working fluid 7 is such a load The 200 is delivered to the diaphragm 1 at a uniform pressure.

At this time, a compressive force, that is, positive pressure (pressure for discharging the fluid to the outside) is applied to the working fluid 7, and a direct pressure due to the load 200 does not act on the storage fluid 7. The working fluid 7 is partially leaked toward the storage fluid 7 through a gap between the ring 412 and the inner surface of the first cylinder member 2. That is, the working fluid 7 is not completely leaked out to the outside, but is included in the storage fluid 8 accommodated inside the second cylinder member 3 through the elastic membrane 6. Here, the elastic membrane 6 may be elastically stretched because it elastically behaves.

For reference, the valve 414 cannot be opened at such a positive pressure, so that the working fluid 7 is partially only through the gap between the ring 412 and the inner surface of the first cylinder member 2 as described above. Can be moved towards the storage fluid (8).

As a part of the working fluid 7 is moved to the storage fluid 8 as described above, the piston member 4 is moved upward by a predetermined distance. In addition, the elastic member disposed between the limiting jaw 21 of the first cylinder member 2 and the supporting jaw 421 of the elastic support 42 of the piston member 4 as the piston member 4 moves upward ( 5) is compressed.

Thereafter, after the load 200 applied to the lower end of the load input part 43 of the piston member 4 is removed, the compressed elastic member 5 is elastically restored again to push the piston member 4 downward. . Accordingly, while the space in which the working fluid 7 is accommodated is extended downward, a negative pressure (pressure for further sucking fluid from the outside) acts on the space in which the working fluid 7 is accommodated.

At this time, the valve 414 is opened upward for the negative pressure, and the working fluid 7 is accommodated again through the fluid supply hole 413 formed in the load transfer part 41. It flows into space. After a part of the storage fluid 8 flows into the working fluid 7 such that the lower end of the limiting protrusion 411 of the load transfer part 41 of the piston member 4 reaches the upper end of the limiting jaw 21, the further The abnormal storage fluid 8 does not flow into the working fluid 7.

In this way, the load 200 is transmitted from the piston member 4 to the diaphragm 1 through the fluid, so that the load 200 in the large uniaxial direction can be measured even if the pressure sensor 100 is small. can do. For example, the pressure sensor 100 may be integrated in the foot portion of the foot walking robot.

In addition, since the load 200 is not transmitted only through the mechanical structure but is evenly transmitted to the diaphragm 1 through the pressure of the working fluid 7, the unbalanced force and impact can be stably transmitted to measure the pressure. . And since the working fluid 7 is close to incompressibility and the deformation of the diaphragm 1 is very fine, there is almost no play that the piston member 4 is pushed.

In addition, since the strain of the diaphragm 1 is measured, by changing the material and thickness of the diaphragm 1 as long as the pressure sensor 100 itself is not destroyed, very high weight can be measured. In addition, by configuring the strain gauge 11 as a Wheatstone bridge, linearity can be secured and the change in output due to temperature is also significantly reduced.

And a configuration of the storage fluid 8, the elastic membrane 6, the valve 414, and the elastic member 5, which interact with the working fluid 7, resulting in breakage of the portion containing the fluid. Can be prevented from being lost, and there is no need to use other external systems to compensate for fluid loss. That is, the fluid leaking from the working fluid 7 is contained in the space in which the storage fluid 8, which does not apply a large pressure through the elastic membrane 6, which can be fluidly stretched, is contained. There is no risk of breakage) can be maximized the stability of the pressure sensor 100 using the fluid.

While the present invention has been particularly shown and described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, And all changes and modifications to the scope of the invention.

100. Pressure sensor
1. Diaphragm 11. Strain Gauge
2. First cylinder member 21. Limit jaw
3. 2nd cylinder member 31. Extension part
32. Cylinder section 321. Cylinder groove
322. Cylinder projection 4. Piston member
41. Load transfer section 411. Restriction protrusion
4111.Ring Grooves 412.Ring Grooves
413. Fluid supply hole 414. Valve
42. Elastic support 421. Supporting jaw
4211. Supporting jaw groove 43. Load input part
5. Elastic member 6. Elastic membrane
61. Once 62. The other end
7. Working fluid 8. Storage fluid
200. Load

Claims (16)

Diaphragm,
A cylinder member extending downward along a circumference of the diaphragm,
A piston member spaced apart from the diaphragm inside the cylinder member,
A working fluid received between the diaphragm and the piston member,
An elastic member provided between the cylinder member and the piston member,
An elastic membrane for sealing between the cylinder member and the piston member, and
It includes a storage fluid accommodated in the space closed by the elastic membrane,
When a load is applied upwardly to the piston member, the load is transmitted to the diaphragm through the working fluid at a pressure, and the piston member moves upward while a part of the working fluid is moved to the storage fluid by the pressure. And the elastic member is deformed,
When the load applied to the piston member is removed, a portion of the storage fluid is moved to the working fluid and the piston member is moved downward by the pressure generated when the deformed elastic member is recovered. In claim 1,
The cylinder member is
A first cylinder member extending downward along the circumference of the diaphragm and having a limiting jaw formed along the circumference of the lower side of the inner side;
A second cylinder member connected downward with respect to said first cylinder member,
And the working fluid is disposed inside the first cylinder member to be in contact with the bottom surface of the diaphragm. In claim 2,
The piston member is
A load transfer part inserted into the first cylinder member to be in contact with a lower end of the working fluid;
An elastic support part connected to the load transfer part and having a support jaw formed along a lower periphery of the outer surface;
And a load input unit connected to the elastic support and receiving a load through a lower end thereof. 4. The method of claim 3,
The load transfer part
Restriction protrusions provided along the circumference of the upper side of the outer surface and located above the limiting jaw,
A ring provided along a circumference of an outer surface of the restricting protrusion to abut on a circumference of an inner surface of the first cylinder member,
A fluid supply hole penetrating the outer surface and the top, and
The valve opens when the negative pressure acts upward from the fluid supply hole and closes when the positive pressure acts downward toward the fluid supply hole.
Pressure sensor comprising a. 4. The method of claim 3,
The elastic member is a pressure sensor installed between the limiting jaw and the support jaw so that the piston member elastically moves in the vertical direction. 4. The method of claim 3,
The elastic membrane is a pressure sensor for connecting the circumference of the inner surface of the second cylinder member and the circumference of the outer surface of the elastic support in a sealed state. 4. The method of claim 3,
And the storage fluid is disposed in a space surrounded by the load transfer part, the first cylinder member, the second cylinder member, the elastic support part, and the elastic membrane. 4. The method of claim 3,
The second cylinder member is
An extension extending outwardly along a circumference at the bottom of the first cylinder member, and
And a cylinder portion extending downward along a circumference from an end in the outward direction of the expansion portion. 9. The method of claim 8,
The cylinder portion includes a cylinder protrusion which forms a cylinder groove into which one end of the elastic membrane is inserted along the circumference of the inner side,
The support jaw is a pressure sensor comprising a support jaw groove is formed along the periphery on the outer surface so that the other end of the elastic membrane is inserted. 5. The method of claim 4,
The positive pressure is generated when the load is input to the load input unit,
The sound pressure is generated when the elastic restoring force of the elastic member that has been elastically compressed after the input of the load to the load input unit is applied to the piston member. 5. The method of claim 4,
The working fluid is a pressure sensor which is included as part of the storage fluid is moved through a portion between the ring and the circumference of the inner surface of the first cylinder member when the positive pressure is applied. 5. The method of claim 4,
The storage fluid is a pressure sensor that is part of the working fluid is moved through the fluid supply hole when the negative pressure is applied. 5. The method of claim 4,
The limiting projection is a pressure sensor that the lower end is in contact with the upper end of the limiting jaw before the load is input. 4. The method of claim 3,
And the load input portion has a shape in which a circumference of an outer surface is engaged with a circumference of an inner surface of the second cylinder member. In claim 1,
The working fluid and the storage fluid are incompressible pressure sensors. In claim 1,
And a strain gauge attached to the diaphragm.

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