JP3263608B2 - Underwater force sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single-axis or multi-axis system for measuring the force and moment applied to a robot or the like underwater, which is used, for example, by attaching it to an underwater operation robot for constructing or inspecting underwater structures. Related to underwater force sensors.

[0002]

2. Description of the Related Art In order to form a force sensor for use in water by using a sensing electric unit of a commonly used air force sensor, it is necessary to prevent water from entering the sensing electric unit. It is necessary to adopt a seal structure. However, accurate detection cannot be performed even if the seal is simply performed with an O-ring.

[0003] That is, in a configuration in which the seal is merely sealed, air remains in the force sensor, and as the pressure outside the force sensor changes due to a change in water depth or the like,
Due to the pressure difference between the inside and outside of the force sensor, the force obtained by multiplying this differential pressure by the area of the load portion receiving the water pressure of the sensing electrical unit is detected as the force acting in the axial direction of the force sensor,
An accurate measurement cannot be made.

[0004] The inventor of the present invention has conducted intensive studies, and as a result, FIG.
We have recently developed a submersible force sensor with the structure shown in the principle diagram. The underwater force sensor according to this prior art accommodates a sensing electrical unit 2 in a waterproof casing 1 in a state where a load unit 2a of the electrical unit 2 is exposed on an outer surface of the casing 1, and includes the load unit 2a The casing 1 is sealed with a sliding seal 3 such as an O-ring, and a part of the casing 1 is provided with an internal / external pressure adjusting mechanism using a flat elastic film 4. The liquid 5 having no property is filled.

In the use of the underwater force sensor having this configuration,
When the external pressure (water pressure) changes, the above-mentioned change in pressure acts on the elastic film 4, which is the softest part of the underwater force sensor, and serves as an internal / external pressure adjusting mechanism, whereby the film 4 is elastically deformed. Thereby, for example, when the external water pressure increases, the elastic film 4 is deformed so as to protrude inside the casing 1 as shown in FIG. Reduce the pressure difference between the outside and the inside to zero. With such pressure compensation, since the external pressure can be accurately received by the load unit 2a of the sensing electric unit 2, it is possible to prevent the external pressure change from affecting the output of the underwater force sensor.

[0006]

By the way, the force and moment applied from the outside to the underwater force sensor according to the prior art underwater not only through the sensing electrical unit 2 in the casing 1 but also through the sliding seal 3. It is also transmitted to the casing 1. However, the underwater force sensor according to the prior art includes a casing 1 and a load unit 2 of a sensing electrical unit 2 exposed on an outer surface thereof.
Since the sliding seal 3 using an O-ring seals the gap between the sliding seal 3 and the a, the resistance of the sliding seal 3 is large. Therefore, a part of the force or moment applied from the outside becomes a loss based on the resistance in the sliding seal 3, and not all of the force or moment is transmitted to the sensing electrical unit 2 in the casing 1. There is a problem that the moment cannot be measured accurately.

The underwater force sensor according to the prior art is provided with a sliding seal 3 for waterproofing to protect the sensing electrical unit 2 from water. Since the configuration is such that the elastic film 4 constituting the pressure adjusting mechanism is attached to the casing 1, there are also problems that the number of parts is large and the structure is complicated. Therefore, an object of the present invention is to provide an underwater force sensor having a simple structure and capable of performing accurate measurement.

[0008]

In order to achieve the above-mentioned object, the invention of claim 1 has a casing 11 and a load portion 12a exposed outside the casing 11, as shown in the principle diagram of FIG. And the sensing electrical unit 12 housed in the casing 11, the load unit 12a and the casing 11
A pressure adjusting film 13 made of an elastic body having a ring-shaped concave deforming portion 13a forming a boundary between the inside and the outside of the casing 11 and projecting toward the inside of the casing 11; And a non-conductive liquid 14 filled therein.

According to the first aspect of the present invention, the casing 11 and the load portion 12a of the sensing electrical unit 12 accommodated therein.
The pressure regulating film 13 provided over the casing seals the casing 11 and protects the electric components inside the underwater force sensor of the present invention from water. Further, the pressure adjusting film 13 compresses or expands the non-conductive liquid 14 which is flexibly deformed according to the pressure outside the hydrodynamic sensor and fills the inside of the casing 11 without sliding the load portion 12a in the axial direction. Thus, the pressure difference between the inside and outside of the casing 11 is reduced to zero. Therefore, the pressure adjusting film 13 also serves as a seal for the casing 11 and an internal / external pressure adjusting mechanism for eliminating a pressure difference between the inside and the outside of the casing 11.

[0010] Then, a pressure adjusting film 1 corresponding to an external pressure.
The flexible deformation of No. 3 is mainly performed at the annular concave deformed portion 13a, but since this deformed portion 13a protrudes into the casing 11, the flexible deformation does not deform in the axial direction of the underwater force sensor. The sensor does not deform in the circumferential direction and does not generate extra force or moment such as pulling the sensing electrical unit 12 due to the deformation. Therefore, the external force or moment applied to the load portion 12a can be accurately transmitted to the sensing electric device 12 without loss.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. FIG. 2 is a side view showing the configuration of the underwater force sensor according to the first embodiment, and FIG.
2 is a partially cutaway view of the configuration of the underwater force sensor according to the first embodiment when viewed from the direction of arrow Z in FIG. 2, and 21 in these figures denotes a waterproof casing. is there.

The casing 21 has a casing main part 21a having a ring shape, and a casing projecting part 21b projecting from a peripheral surface of the main part 21a. An inward flange 22 protruding inward from one end opening edge of the casing main portion 21a is provided, and a film mounting groove 22a is formed in the flange 22. The groove 22a has an annular shape along the circumferential direction of the casing main part 21a.

Inside the casing main portion 21a of the casing 21, a sensing electrical unit 23 for sensing a force (water pressure) or a moment acting in water is accommodated. Electrical part 2
Reference numeral 3 denotes a disk-shaped fixing portion 24, a load portion 25 having a smaller diameter than this, a sensing portion 26 in which these two portions 24, 25 are integrally connected at a central portion, and a surrounding portion surrounding the sensing portion 26. And a side wall portion 27 connecting both portions 24 and 25 integrally. The load section 25 has a step 25a on its periphery. A strain gauge (not shown) is attached to the inner peripheral surface of the sensing unit 26. This gauge detects the distortion of the sensing unit 26 according to the underwater force or moment received by the load unit 25, converts the distortion into an electric quantity (voltage) according to the amount of the distortion, and outputs it. The side wall portion 27 has a through hole 27a communicating the inside and outside thereof.

The sensing electrical unit 23 is accommodated in the casing 21 such that the outer peripheral surface of the fixing unit 24 is in contact with the inner peripheral surface of the casing main part 21a, and is fixed to the casing main part 21a by a plurality of bolts 28. I have. Sealing means 29 such as an O-ring is provided between the casing main portion 21a and the fixing portion 24 to seal between them. As shown in FIG. 3, the fixing portion 24 is disposed so as to be exposed outside the casing 21 by closing the rear opening of the casing main portion 21 a in a liquid-tight manner, and the load portion 25 It is provided at an interval inside the inward flange 22 and is arranged so that its front surface is exposed outside the casing 21.

The inward flange 22 and the step 25a are at the same height. A ring-shaped casing lid 30 that covers the inward flange 22 from the front side of the casing 21 is fixed by a plurality of bolts 31. Similarly, the step portion 25a is also provided with the casing 21.
A ring-shaped sensing portion cover 32 that covers from the front side of is fixed by a plurality of bolts 33. The two lids 30, 32
A ring-shaped gap G is formed between them.

A pressure adjusting film 34 for sealing between the casing 21 and the load 25 is attached across the casing 21 and the load 25. Specifically, the pressure adjusting film 34
Has a thick base end 3 at one end.
The portion other than the portion 4a is thin and elastically deformable, and has an annular concave deformed portion 34b bent at an intermediate portion. The pressure adjusting film 34 is made of rubber or an elastic material similar thereto, and has a base end 34.
a into the membrane mounting groove 22a so that the inward flange 2
2 and the casing lid 30, and the other thin end is sandwiched and attached between the step 25 a and the sensing part lid 32. The bolt 33 is screwed into the step 25a through the other thin end. With this attachment, the pressure adjusting film 34 is provided as a boundary between the inside and the outside of the casing 21.

The concave deforming portion 34b protrudes in the axial direction toward the inside of the casing 21, in other words, the fixing portion 2b.
4 protruding. The deformed portion 34b has a substantially U-shaped or substantially V-shaped cross section, and has a substantially step-shaped bent over the entirety thereof so that flexible deformation can be more easily performed.

A connector 35 for supplying electric power to the sensing unit 26 and guiding an electric signal obtained by the sensing unit 26 to the outside is attached to the casing protrusion 21b. The connector 35 is of a type that is sealed independently, so that the sealing performance of the casing 21 is not impaired.

Further, a passage 36 is formed in the casing projecting portion 21b so as to communicate between the inside and the outside of the casing main portion 21a and to pass wires and the like.
The end of the casing 6 on the side of the casing projecting portion 21b is normally closed by a plug 37 in a watertight manner. The casing 21 is filled with a liquid 38 having a specific gravity higher than that of water such as silicon oil and having no conductivity.

The passage 36 is used for filling a liquid 38. The filling of the liquid 38 and the wiring operation of the plug 37 to the passage 36 after the filling are performed in the liquid 38, whereby the casing 21
The liquid 38 is filled in the casing 21 so as to prevent air from remaining inside.

In the force sensor having the above-described structure, the casing 21 and the fixing portion 2 of the sensing electric unit 23 accommodated therein are provided.
4 is sealed by a sealing means 29 such as an O-ring sandwiched between the casing 4 and water. The thick end (base end 34a) of the pressure adjusting film 34, which is itself made of an elastic body and is a sealing material, is sandwiched and fixed between the inward flange 22 of the casing 21 and the casing lid 30. Water does not enter the casing 21 from this portion, and the other thin end of the pressure adjusting film 34 is sandwiched and fixed between the step portion 25a of the load portion 25 and the sensing portion lid 32. Water does not enter the casing 21 from the inside.

Therefore, the sensing electrical unit 2 of this force sensor
The sensor 26 in FIG. 3 is sealed by being surrounded by the casing 21, the sealing means 29, and the pressure adjusting film 34 to prevent water from entering the sensor 26, so that the force sensor can be used underwater. For example, it is used by being attached to an underwater work robot or the like that performs construction or inspection of an underwater structure, and measures a force or moment applied to the robot or the like underwater.

When the underwater force sensor is used underwater, the fixing portion 24 and the load portion 25 of the sensing electrical unit 23 are exposed to the outside of the casing 21, respectively. Is directly transmitted to the sensing unit 26 of the sensing electrical unit 23 without passing through an extra member such as a seal. Accordingly, as the sensing unit 26 is distorted, the amount of distortion is detected by a strain gauge attached to the inner surface of the sensing unit 26, and the force or moment is measured as an electric amount corresponding to the amount of distortion. .

In such a measurement, since the casing 21 is filled with the non-conductive liquid 38, even if the pressure outside the underwater force sensor changes due to a change in water depth or the like, it does not affect the sensor output. I will not give.

That is, when the pressure (water pressure) outside the sensor changes, the change in the pressure acts on the pressure adjusting film 34 made of an elastic body, which is the softest part of the underwater force sensor, and serves as an internal and external pressure adjusting mechanism. The concave deformed portion 34b of the pressure adjusting film 34 is mainly deformed flexibly. Thereby, for example, when the water pressure outside the sensor increases, the concave deformed portion 34b of the pressure adjusting film 34 is deformed so as to expand according to the increase in the pressure, and compresses the liquid 38 in the casing 21. The pressure difference between the outside and the inside of the casing 21 can be made zero. Conversely, when the pressure outside the sensor decreases, the concave deformed portion 34b of the pressure adjusting film 34 is flexibly deformed so as to wither in accordance with the pressure decrease, and the liquid 38 in the casing 21 expands. Therefore, the pressure difference between the outside and the inside of the casing 21 can be reduced to zero.

Since the pressure inside the casing 21 is compensated for the pressure change outside the sensor, only the external pressure can be accurately received by the load unit 25 of the sensing electrical unit 23 and the like. It does not affect the output of the sensor.

Moreover, the concave deforming portion 3 for compensating the pressure is provided.
4b, an extra force or moment is applied to the load portion 25.
Can be prevented. That is, as described above, the flexible deformation of the pressure adjusting film 34 according to the external pressure change is
Although mainly performed in the annular concave deformed portion 34b,
Since the deformed portion 34b protrudes in the axial direction into the casing 21, it does not deform in the axial direction of the underwater force sensor but deforms in the circumferential direction of the underwater force sensor in its flexible deformation.

Therefore, no extra force or moment such as pulling the load portion 25 of the sensing electric device 23 is generated due to the deformation of the concave deforming portion 34b, and the deformation of the sensing electric device 23 according to the external force is prevented. There is no.

As described above, in addition to the fact that the pressure difference between the inside and the outside of the casing 21 can be maintained at zero, the flexible deformation of the pressure adjusting film 34 at the concave deformed portion 34b causes an extra force or Applying a moment can be prevented. Therefore, in the water, the load 2
5 is transmitted to the casing 21 via the pressure adjusting film 34 and is not lost, so that the force applied from the outside of the sensor regardless of the pressure change outside the sensor. And the moment can be accurately measured in the sensing electrical unit 23.

Further, in this underwater force sensor, as described above, the pressure adjusting film 34 provided between the casing 21 and the load 25 of the sensing electrical unit 23 is
In addition to sealing between the casing 21 and the load portion 25, the casing 21 also serves as an internal / external pressure adjusting mechanism for eliminating a pressure difference between the inside and the outside of the casing 21. Therefore, the number of components is reduced and the structure can be simplified as compared with the conventional configuration in which the seal and the internal / external pressure adjusting mechanism are separately provided.

[0031]

The present invention is embodied in the form described above and has the following effects. According to the first aspect of the present invention, an internal / external pressure adjusting mechanism for eliminating a pressure difference between the casing and the casing and a casing by a pressure regulating film for sealing between the casing and the load portion of the sensing electrical unit exposed outside the casing. , The number of parts is reduced, and the structure can be simplified. In addition, since the external force or moment applied to the load unit is transmitted to the sensing electrical unit without loss, accurate measurement can be performed.

[Brief description of the drawings]

FIG. 1 is a principle diagram showing a configuration of a submersible force sensor according to a first embodiment of the present invention.

FIG. 2 is a side view showing the configuration of the underwater force sensor according to the first embodiment.

FIG. 3 is a partially cutaway view of the configuration of the underwater force sensor according to the first embodiment when viewed from the direction of arrow Z in FIG. 2;

FIG. 4 is a principle view showing a configuration of a underwater force sensor according to the prior art of the present invention.

[Explanation of symbols]

 11, 21 ... casing, 12, 23 ... sensing electric part, 12a, 25 ... load part, 13, 34 ... pressure adjusting film, 13a, 34b ... concave deformed part, 14, 38 ... liquid.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References Japanese Utility Model Sho 59-187734 (JP, U) Japanese Utility Model Sho 56-79810 (JP, U) Japanese Utility Model Sho 62-62941 (JP, U) Japanese Utility Model Sho 50- 15505 (JP, Y1) Jikken 39-36730 (JP, Y1) (58) Field surveyed (Int. Cl. ⁷ , DB name) G01L 1/26 G01L 1/22

Claims (1)

(57) [Claims] 1. A casing, a sensing electrical unit having a load portion exposed outside the casing and housed in the casing, and a casing provided between the load portion and the casing so as to be sealed. A pressure regulating film made of an elastic body having an annular concave deforming portion forming an inner / outer boundary and protruding toward the inside of the casing; and a non-conductive liquid filled in the casing. Sensor.