JP2001183247A - Pressure detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pressure detector capable of detecting the deterioration of a conductive part or the like. SOLUTION: A conductor 72 is buried in a coating part 30 forming an electrode wire 26, separately from a main conductor 28, and a current value of the electric current flowing to the conductor 72 from the conductor 28 through the coating part 30 is detected. When the coating part 30 is deteriorated and a resistance value is changed, the current value of the electric current flowing from the conductor 28 through the coating part 30 is also changed, whereby whether the resistance value is changed caused by the deterioration of the coating part 30 or not can be determined on the basis of a result of the detection.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure detecting device for detecting whether an external force acts on a predetermined portion.

[0002]

2. Description of the Related Art In a pressure detecting device for detecting whether or not an external force acts on a predetermined portion, a pressure-sensitive sensor is usually arranged at the predetermined portion. Here, FIG. 12 shows an example of a pressure-sensitive sensor in a perspective view. As shown in FIG. 12, the pressure-sensitive sensor 140 has an outer skin 142. The outer skin portion 142 is formed in a long string shape by an elastically deformable member having an insulating property such as rubber, and has a substantially cross-shaped cross-section inside thereof, and the outer skin portion is displaced along the longitudinal direction of the outer skin portion 142. A cross hole 144 that is gradually rotated around the center of the cross section of the portion 142 is formed. Further, the inside of the outer skin portion 142 is provided with book electrode wires 146 and 14.
8, 150, 152 are arranged so as to face each other via a cross hole 144. These electrode wires are helically arranged around the center of the outer cover 142 in accordance with the rotational displacement of the cross hole 144 along the longitudinal direction of the outer cover 142.

Each of the electrode wires 146 to 152 has a conductive wire 154 formed by twisting a thin metal wire such as copper, and a covering portion 156 formed of a flexible conductive synthetic resin material and covering the conductive wire 154. It consists of.

FIG. 11 schematically shows a pressure detecting device 160 to which the above-mentioned pressure-sensitive sensor 140 is applied. As shown in this figure, the electrode wire 146 and the electrode wire 150 are conductive at one end in the longitudinal direction, and the electrode wire 148 and the electrode wire 152 are also conductive at one end in the longitudinal direction. The electrode wire 150 and the electrode wire 148 are electrically connected via the resistor 162 at the other end in the longitudinal direction. Further, the electrode wire 14
The other longitudinal end of each of 6, 152 is connected to a power source via a cord 164. However, only the electrode wire 152 is connected to a power supply via a current detection element 166 that cuts off the circuit when a current of a predetermined value or more flows. That is, the current flowing from the electrode wire 146 to the electrode wire 152 via the electrode wires 150 and 148 normally flows via the resistor 162, but if the outer cover portion 142 is crushed and the electrode wire 1
46 or the electrode wire 150 is the electrode wire 148 or the electrode wire 1
When a short circuit occurs due to conduction with the resistor 52, the current flows without passing through the resistor 162. For example, if a current flows through this circuit at a constant voltage, the current value changes. The current detecting element 166 that has detected the change in the current value outputs a signal to the computer 168.
And the like, it is possible to detect whether or not the outer cover 142 is crushed, that is, whether or not an external force acts on the pressure-sensitive sensor 140.

[0005]

As described above, the conducting wires 154 of the electrode wires 146 to 152 are not covered by the covering portion 1.
Although the coating portion 156 is covered with the synthetic resin material, the coating portion 156 may be deteriorated with time because of the synthetic resin material. Values can change.

For example, if the resistance value of the covering portion 156 increases due to deterioration or the like, the current detecting element 166 is naturally formed when the electrode line 146 or 150 and the electrode line 148 or 152 come into contact and conduct. Detects a smaller current. For this reason, if the intrinsic resistance value of the covering portion 156 increases until the current value becomes lower than the lower limit of the current value that can be detected by the current detection element 166, the electrode wire 146 or the electrode wire 1
Even when the electrode 50 and the electrode wire 148 or the electrode wire 152 come into contact with each other and become conductive, the current value at that time is the current detection element 166
Is below the lower limit of the current value that can be detected, the current detection element 166 does not send a signal to the computer 168 and consequently cannot detect whether an external force acts on the pressure-sensitive sensor 140.

An object of the present invention is to provide a pressure detecting device capable of detecting deterioration of a conductive portion in consideration of the above fact.

[0008]

According to a first aspect of the present invention, there is provided a pressure detecting device, comprising: a plurality of electrodes in which a conductive wire formed by a conductive thin wire is covered with a flexible covering portion provided with a conductive property; A pressure-sensitive sensor connected in series while being spaced apart from each other via a gap inside a hollow outer skin portion that is elastically deformable by receiving an external force, and at least one of the plurality of electrode wires Detecting means for detecting a change in the electric resistance value due to the two contacting each other; and electrically connecting to at least one of the plurality of electrodes to determine whether or not the electric resistance value of the covering portion has changed. And determination means for determining.

In the pressure detecting device having the above structure, when the outer skin of the pressure-sensitive sensor receives an external force, the outer skin is elastically deformed, and at least one of the plurality of electrodes arranged in the outer skin is elastically deformed due to the elastic deformation of the outer skin. It bends and approaches another electrode. Since the plurality of electrodes are connected in series, when this bent electrode comes into contact with another electrode and conducts (short-circuits) with the other electrode, the electric resistance including the plurality of electrodes changes. Then, it is detected that an external force acts on the outer skin portion where the change in the electric resistance value is detected by the detecting means, that is, that a pressure acts on the pressure-sensitive sensor.

On the other hand, at least one of the plurality of electrodes
In the end, a determining means is electrically connected, and the determining means determines whether or not the specific resistance value of the covering portion constituting the electrode has changed. Therefore, for example, when the determination unit determines that the electric resistance value is a unique electric resistance value of the covering portion to the extent that a problem occurs in the detection of the change in the electric resistance value when the plurality of electrodes come into contact with each other by the detection unit. A state in which it is difficult to detect pressure externally by a warning unit that uses sound or light as a warning signal, such as a monitor, a horn, or a warning light, based on the determination result of the determination unit (when the pressure sensor is replaced ).

According to a second aspect of the present invention, there is provided a pressure detecting device.
In the present invention described above, the determination means detects a current that is electrically connected to the covering portion and flows through the covering portion.

In the pressure detecting device having the above-described structure, the judging means is connected to the covering portion of the electrode, and detects the current flowing through the covering portion. The judging means detects the specific resistance of the covering portion from the change in the current value. It is determined whether the value has changed. That is, the present pressure detection device directly detects and determines a change in the unique electric resistance value of the covering portion. Therefore, the reliability of the determination result is high.

According to a third aspect of the present invention, there is provided a pressure detecting device.
In the present invention described above, the determination means is formed of the same material as the covering portion, and is electrically connected to the conductor downstream of any one of the plurality of electrodes along the flow of the current. And detecting a current downstream of the resistor along the flow of the current.

In the pressure detecting device having the above structure, a resistor is electrically connected to any one of the plurality of electrodes. Here, since the resistor is formed of the same material as the covering portion, the temporal change of the intrinsic resistance value of each of the covering portion and the resistor is substantially the same. Therefore, if the resistance value has changed due to the deterioration of the covering portion, the current value of the current flowing through the resistor changes, and the determination means determines whether or not this current value has changed.

As described above, in the present pressure detecting device, the determination means detects and determines indirectly a change in the electric resistance value inherent to the covering portion from a change in the current value flowing through the resistor. For this reason, the pressure-sensitive sensor and the determination unit can be structurally separated.

According to a fourth aspect of the present invention, there is provided a pressure detecting device.
The present invention according to any one of claims 3 to 5, further comprising a warning unit that issues a warning signal when the determination unit determines that the electric resistance value of the covering portion has changed.

In the pressure detecting device having the above structure, when the judging means judges that the specific electric resistance value of the covering portion has changed, based on the judgment result of the judging means, a monitor, a horn or a warning light is used. Warning means emits a warning signal such as sound or light. Thereby, it is possible to notify the outside that the detection of the pressure is difficult (time to replace the pressure-sensitive sensor).

[0018]

FIG. 6 is a sectional view showing the structure of a pressure-sensitive sensor 12 used in a pressure detecting device 10 according to a first embodiment of the present invention. FIG. 1
2 is shown in a partially broken perspective view.

As shown in these figures, the pressure-sensitive sensor 12 is made of an insulating rubber material such as silicone rubber, ethylene propylene rubber, styrene butadiene rubber, chloroprene rubber, or a polyethylene, ethylene-vinyl acetate copolymer. A long outer skin portion 14 made of an insulating elastic material such as ethylene ethyl acrylate copolymer, ethylene methyl methacrylate copolymer, polyvinyl chloride, olefin-based, or styrene-based thermoplastic elastomer. ing. A cross hole 16 having a cross-shaped cross section is formed inside the outer skin portion 14 along the longitudinal direction of the outer skin portion 14. As shown in FIG. 7, the cross hole 16 is gradually displaced around the center of the outer skin portion 14 along the longitudinal direction of the outer skin portion 14.

Further, long cord-shaped electrode wires 20, 22, 24, 26 are provided inside the outer cover portion 14. Each of the electrode wires 20 to 26 is composed of a conductive wire 28 formed in a long string shape having flexibility by bringing together a conductive thin wire such as a copper wire, and a synthetic wire having a conductive property and flexibility. And a cover portion 30 formed of a resin material and covering the conductive wire 28.
6 and are spirally arranged along the cross hole 16 and are integrally fixed to the inner peripheral portion of the cross hole 16. Therefore, the electrode wires 20 to 26 are bent by the elastic deformation of the cross hole 16, and in particular, if the outer skin portion 14 is elastically deformed to the extent that the cross hole 16 is crushed, the electrode wire 20 or the electrode wire 24 and the electrode wire 22 or the electrode wire The line 26 contacts and conducts.
When the cross hole 16 is restored, the electrode wires 20 to 26 are also restored.

On the other hand, as shown in FIGS. 1 and 2, a plate-like support piece 32 made of an insulating synthetic resin or the like is provided at one end in the longitudinal direction of the outer cover portion 14. I have. As shown in FIG. 2, on one side of the support piece 32, a resistor 34 and a connection piece 3 made of metal or the like are provided.
6, 38 are fixed. An end of a lead wire 40 drawn out of the resistor 34 is fixed to one end of the connection piece 36 and is electrically connected to the connection piece 36. A lead wire 42 drawn out of the resistor 34 is connected to one end of the connection piece 38. Are fixed and electrically connected to the connection piece 38. On the other hand, the other end of the connecting piece 36 is fixed to one end of a conducting wire 28 drawn out of the electrode wire 22 and is electrically connected to the connecting piece 36. The other end of the connecting piece 38 is connected to the conducting wire drawn out of the electrode wire 24. One end of the wire 28 is fixed and is electrically connected to the connection piece 38. In this way,
The electrode line 22, the resistor 34, and the electrode line 24 are connected in series.

On the other hand, as shown in FIG. 1, connection pieces 44 and 46 are fixed to the other side of the support piece 32. An end of a conductor 50 drawn from a cord 48 is fixed to the connection piece 44 and is electrically connected to the connection piece 44. An end of a conductor 52 drawn from the cord 48 is fixed to the connection piece 46 and connected. It is electrically connected to the piece 46. On the other hand, a conducting wire 28 drawn out from one end of the electrode wire 20 is fixed to the other end of the connecting piece 44 and is electrically connected to the connecting piece 44. An end of the conducting wire 28 drawn out from the electrode wire 26 is connected to the connecting piece 46. The portion is fixed and electrically connected to the connection piece 46.

As shown in FIGS. 3 and 4, a plate-like support piece 54 made of an insulating synthetic resin or the like is provided at the other end in the longitudinal direction of the outer cover 14. I have. As shown in FIG. 3, a connection piece 56 formed in a substantially U shape by metal or the like is fixed to one side of the support piece 54. The other end of the conducting wire 28 drawn out of the electrode wire 20 is fixed to one end of the connecting piece 56 and is electrically connected to the connecting piece 56. The other end of the connecting piece 56 is connected to the conducting wire 28 drawn out of the electrode wire 24. The other end is fixed and electrically connected to the connection piece 56.

On the other hand, on the other side of the support piece 54, a connection piece 58 formed in a substantially U shape by metal or the like is fixed. The other end of the conducting wire 28 drawn from the electrode wire 22 is fixed to one end of the connecting piece 58 and is electrically connected to the connecting piece 58. The other end of the connecting piece 58 is connected to the conducting wire 28 drawn from the electrode wire 24. The other end is fixed and electrically connected to the connection piece 58.

As described above, the electrode wire 20 and the electrode wire 2
4, the resistor 34, the electrode line 22, and the electrode line 26 are connected in series.

As shown in the circuit diagram of FIG. 5, the conductor 50 of the above-described cord 48 is directly or indirectly connected to a power supply 60, and the conductor 52 is directly or indirectly connected to a current detecting element as a detecting means. 62, and indirectly grounded via the current detecting element 62.

The current detecting element 62 is electrically connected to a computer 64 as a determining means, and further, the computer 64 is electrically connected to a warning device 66 as a warning means such as a horn, a warning light, and a monitor. Have been. The current detection element 62 emits a signal when detecting a current equal to or more than a predetermined value,
When this signal is received by the computer 64, the computer 64 activates the alarm device 66.

Here, as shown in FIGS. 6 and 7,
Inside the covering portion 30 constituting the electrode wire 26, a conducting wire 72 as a determining means is embedded in addition to the conducting wire 28. The conductive wire 72 is basically the same as the conductive wire 28, and is embedded in the covering portion 30 in parallel with the conductive wire 28 constituting the electrode wire 26.

One end of the conducting wire 72 in the longitudinal direction is connected to the conducting wire 28.
At the same time, it is pulled out from the outer skin portion 14 and the covering portion 30 and is electrically connected to a current detecting element 74 as a determination means via a lead wire 80 and then grounded. The current detecting element 74 is electrically connected to the computer 64 similarly to the current detecting element 62, and sends a signal to the computer 64 when the current flowing through the conductor 72 becomes less than a predetermined value.

As described above, since the covering portion 30 is formed of a conductive synthetic resin material,
The conductive wire 28 and the conductive wire 72 constituting the electrode 6 are electrically connected to each other via the coating 30 constituting the electrode wire 26. Since the covering portion 30 naturally has an inherent electric resistance, the covering portion 30 of the electrode wire 26 for electrically connecting the conducting wire 28 and the conducting wire 72 of the electrode wire 20 has the resistance 76 shown in FIG.
Can be considered.

Next, the operation and effect of this embodiment will be described.

In the pressure detecting device 10, usually, a power supply 60
, A DC current flows through the electrode wire 20, the electrode wire 24, the resistor, the electrode wire 22, and the electrode wire 26. Further, the current flowing through the conductive wire 28 of the electrode wire 26 is grounded via the current detecting element 62, and also flows through the conductive wire 72 via the covering portion 30 constituting the electrode wire 26 and is grounded via the current detecting element 74. You.

When a pressing force acts on the outer skin portion 14 from the outside in the radial direction and the outer skin portion 14 is elastically deformed and the electrode wire 20 or the electrode wire 24 comes into contact with the electrode wire 22 or the electrode wire 26, the electric current is reduced. Therefore, the current flowing through the circuit increases. Thus, when a current equal to or more than a predetermined value flows, the current detection element 62 in the circuit sends a signal to the computer 64. Upon receiving this signal, the computer 64 activates the warning device 66 to notify that the outer cover 14 has been elastically deformed, that is, that an external force (pressing force) has acted on the pressure-sensitive sensor 12.

By the way, when the coating portion 30 constituting each of the electrode wires 20 to 26 deteriorates with time and the specific electric resistance value of the coating portion 30 increases, the electrode wire 20 or the electrode wire 24
Although the current flowing when the electrode wire 22 or the electrode wire 26 comes into contact with the conductive wire decreases, the conductive wire electrically connected to the conductive wire 28 forming the electrode wire 26 via the coating portion 30 forming the electrode wire 26 The current flowing to 72 also decreases.

Here, even when the pressing force does not act on the outer sheath portion 14 with respect to the conductive wire 72, the current flows through the covering portion 30 constituting the electrode wire 26. As described above, the electric resistance value of the coating portion 30 increases due to deterioration over time, and when the current flowing through the conductor 72 falls below a predetermined value, a signal is generated from the current detection element 74.
Upon receiving this signal, the computer 64 activates the warning device 66, and if the covering portion 30 is degraded or the like, a pressing force is applied to the outer cover portion 14 and the electrode wire 20 or 24 and the electrode wire 22 are temporarily pressed. Alternatively, it notifies that no current exceeding a predetermined value flows even if the electrode wire 26 comes into contact with the electrode wire 26. As described above, in the present embodiment, a failure can be notified in advance, and thus, in such a case, the pressure can be always reliably detected by replacing the pressure-sensitive sensor 12.

Next, a second embodiment of the present invention will be described. In the description of the present embodiment, parts that are basically the same as those in the first embodiment are given the same reference numerals, and the description thereof will be omitted.

FIG. 10 is a sectional view showing the structure of a pressure-sensitive sensor 92 applied to a pressure detecting device 90 according to a second embodiment of the present invention. As shown in this figure, in the present embodiment, the electrode wire 9 is replaced with the electrode wire 9.
4 are employed. The electrode wire 94 is formed by the covering portion 30 and the conductive wire 2.
8 and does not include the conducting wire 72.
That is, it has the same configuration as the other electrode wires 20 to 24.

As shown in FIG. 8, a support piece 54 is provided on one side of the pressure-sensitive sensor 12 in the longitudinal direction. The structure of the support piece 54 is basically the first
This is the same as the support piece 32 in the embodiment, but a rubber piece 96 as a resistor is arranged on the other side.
The rubber pieces 96 cover the covering portions 30 constituting the respective electrode wires 20 to 26.
It is formed of the same material as the rubber material. Rubber piece 96
One end of each of the lead wires 98 and 100 is fixedly connected to the rubber piece 96. The other end of the lead wire 98 is connected to the conducting wire 106 of the cord 104 to conduct, and is further grounded via the cord 104 and the current detecting element 74 as shown in FIG.

On the other hand, the other end of the lead wire 100 is
And is electrically connected to the conductor 28 of the electrode wire 94 via the connection piece 46.

As described above, the fact that the covering portion 30 itself has an inherent electric resistance means that the rubber piece 96 formed of a conductive synthetic resin material of the same material as the covering portion 30 is covered. There is the same inherent electrical resistance as part 30. Therefore, the rubber piece 96 is connected to the cord 1 as shown in FIG.
It can be regarded as a resistance 108 between the conductor 106 of the wire 04 and the conductor 28 of the electrode wire 94.

In the pressure detecting device 90 having the above-described structure, the electrode wire 20, the electrode wire 24, the resistor 34, the electrode wire 2
2. DC current flows through the electrode wire 94. Further, the electrode wire 9
4 is grounded via the current detecting element 62 and the rubber piece 96 is connected via the lead wire 98.
After flowing through the lead wire 100, it is grounded via the current detecting element 74.

Here, in the present embodiment, each electrode wire 20
When the covering portion 30 forming the components 26 to 26 deteriorates with time, the rubber piece 96 of the same material also deteriorates. When the rubber piece 96 deteriorates and the inherent electric resistance of the rubber piece 96 increases, and the current flowing through the cord 104 falls below a predetermined value, a signal is generated from the current detection element 74 and the signal is received. The computer 64 activates the warning device 66,
Due to a cause such as deterioration of the covering portion 30, if the outer skin portion 1 is temporarily
Even when the pressing force acts on the electrode wire 4 and the electrode wire 20 or the electrode wire 24 comes into contact with the electrode wire 22 or the electrode wire 26, it informs that no current exceeding a predetermined value flows. As described above, according to the present embodiment, a defect can be notified in advance,
In such a case, the pressure can always be reliably detected by exchanging the pressure sensor 92 and the rubber piece 96.

As described above, in this embodiment, basically, the same effects as those of the first embodiment can be obtained. Furthermore, since the pressure sensor 92 used in the present embodiment has basically the same configuration as the conventional pressure sensor 142 described in the related art, the conventional pressure sensor 142 is used as it is. There is an advantage that it can be diverted. On the other hand, in the above-described embodiment, since the rubber piece 96 performs the same function as the covering portion 30 forming the electrode wire 26 in the first embodiment, the pressure-sensitive sensor 92 and the rubber piece 96 are replaced at the time of replacement. It needs to be replaced,
The first embodiment has an advantage that only the pressure sensor 12 needs to be replaced.

[Brief description of the drawings]

FIG. 1 is an enlarged view of one end of a pressure-sensitive sensor used in a pressure detecting device according to a first embodiment of the present invention and one side in a thickness direction of a support piece.

FIG. 2 is an enlarged view of one end of a pressure-sensitive sensor used in the pressure detecting device according to the first embodiment of the present invention and the other side in the thickness direction of the support piece.

FIG. 3 is an enlarged view of the other end of the pressure-sensitive sensor used in the pressure detecting device according to the first embodiment of the present invention and one side in the thickness direction of the support piece.

FIG. 4 is an enlarged view of the other end of the pressure-sensitive sensor used in the pressure detecting device according to the first embodiment of the present invention and the other side in the thickness direction of the support piece.

FIG. 5 is a circuit diagram schematically showing a configuration of a pressure detecting device according to the first embodiment of the present invention.

FIG. 6 is a cross-sectional view of a pressure-sensitive sensor used in the pressure detecting device according to the first embodiment of the present invention.

FIG. 7 is an enlarged perspective view of a pressure-sensitive sensor used in a pressure detecting device according to a second embodiment of the present invention.

FIG. 8 is an enlarged view of one end of a pressure-sensitive sensor used in a pressure detecting device according to a second embodiment of the present invention and one side in a thickness direction of a support piece.

FIG. 9 is a circuit diagram schematically illustrating a configuration of a pressure detection device according to a second embodiment of the present invention.

FIG. 10 is a sectional view of a pressure-sensitive sensor used in a pressure detecting device according to a second embodiment of the present invention.

FIG. 11 is a circuit diagram schematically showing a configuration of a conventional pressure detecting device.

FIG. 12 is a sectional view of a pressure-sensitive sensor used in a conventional pressure detecting device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Pressure detector 12 Pressure sensor 14 Outer skin part 20 Electrode wire (electrode) 22 Electrode wire (electrode) 24 Electrode wire (electrode) 26 Electrode wire (electrode) 62 Current detection element (detection means) 64 Computer (determination means) 72 Conducting wire (determining means) 74 Current detecting element (determining means) 90 Pressure detecting device 92 Pressure-sensitive sensor 94 Electrode wire (electrode) 96 Rubber piece (resistor, determining means)

Claims (4)

[Claims] A plurality of electrodes, each of which is formed by covering a conductive wire formed of a conductive thin wire with a flexible covering portion provided with a conductive property, has a hollow outer skin portion that can be elastically deformed by receiving an external force. A pressure-sensitive sensor connected in series while being spaced apart from each other via a gap on the inside, and detecting a change in electric resistance value due to at least any two of the plurality of electrode wires coming into contact with each other. A pressure detecting device, comprising: detecting means for detecting whether the electric resistance value of the covering portion has been changed by being electrically connected to at least one of the plurality of electrodes. 2. The pressure detecting device according to claim 1, wherein said judging means detects a current which is electrically connected to said coating portion and flows through said coating portion. 3. The determination means is formed of the same material as the covering portion, and electrically connected to the conductor downstream of any one of the plurality of electrodes along the flow of the current. The pressure detection device according to claim 1, further comprising a connected resistor, wherein the current is detected downstream of the resistor along the flow of the current. 4. The apparatus according to claim 1, further comprising a warning unit that issues a warning signal when the determination unit determines that the electric resistance value of the covering unit has changed. Pressure detector.