JP2011038469A - Diaphragm pump device of gas detector and portable explosion-proof gas detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a diaphragm pump device of a gas detector and a portable explosion-proof gas detector, capable of providing excellent startability, while saving electric power. <P>SOLUTION: This diaphragm pump device of the gas detector is constituted so that a diaphragm is reciprocated via a driving rod by driving a driving DC motor (hereinafter referred to as "a motor") in the normal rotation direction in an ordinary driving state, and is stopped in a low strain position small in a strain quantity of the diaphragm by stopping of the motor. When starting the motor, a preliminary driving process and an ordinary driving process of driving the motor in the normal rotation direction by normal rotation driving voltage of a predetermined size, are performed, and in the preliminary driving process, the motor is driven in the reverse rotation direction by reverse rotation driving voltage smaller than the normal rotation driving voltage, and the diaphragm is deformed in the inverse direction of the deforming direction of becoming maximum in the strain quantity in the first place in the ordinary driving process. The portable explosion-proof gas detector includes the diaphragm pump device. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a diaphragm pump device for a gas detector and a portable explosion-proof gas detector including the diaphragm pump device.

  In general, for example, in underground construction sites, tunnels, other places where people enter or work areas, the concentration of dangerous gases such as carbon monoxide gas and hydrogen sulfide gas contained in the air in the environment is high. Alternatively, various types of portable gas detectors have been proposed so far in order to monitor the danger to humans due to low oxygen gas concentration. For example, gas detectors have been proposed. The thing of the structure provided with the diaphragm pump apparatus by a motor drive in the main body is known (for example, refer patent document 1).

  In such a motor-driven diaphragm pump device, for example, when the output shaft of the driving motor is rotated, for example, the circular eccentric cam fixed in an eccentric state to the output shaft is rotated, thereby the circular eccentric cam. The drive rod is reciprocated linearly through this, whereby the central portion of the diaphragm is reciprocated, and the pressure in the pump chamber defined by the diaphragm is reduced or increased, for example, supply or discharge of air is performed. It is supposed to be done.

JP 2005-134331 A

  Thus, in a portable gas detector, a primary battery such as a dry battery or a secondary battery (storage battery) is usually used as a driving power source, and a sufficient output can be obtained when starting the driving motor. This may be difficult, and there is a problem that the diaphragm pump device cannot be reliably started. That is, in the diaphragm pump device configured as described above, in order to obtain a stable rotation state of the drive motor, normally, when the drive motor is started, the maximum drag of the diaphragm (the diaphragm is deformed so as to compress the pump chamber). In some cases, it is difficult to ensure a sufficiently large motor drive voltage in a battery-powered portable gas detector where a larger torque than the drag when the amount of diaphragm distortion becomes maximum is required. In this case, the drive rod cannot be moved beyond the maximum strain position where the amount of distortion of the diaphragm is maximum, and the drive motor is stopped.

  Also, when the portable gas detector is used in an environment where there is a risk of ignition, normally, for example, a current such as a resistor or a posistor is provided between the driving power source and the sensor or signal processing circuit. Intrinsically safe explosion-proof measures can be taken, such as inserting a limiting element to supply power in a state where ignition to flammable gas is prevented as much as possible even by a short circuit in a sensor or signal processing circuit. Therefore, there is a problem that it is more difficult to secure a motor driving voltage that can reliably drive the diaphragm pump device.

  The present invention has been made based on the circumstances as described above, and can save power and provide a diaphragm pump device for a gas detector that can obtain excellent startability, and the diaphragm pump device. An object is to provide a portable explosion-proof gas detector.

The diaphragm pump device of the gas detector of the present invention is a diaphragm pump device for supplying a test gas to a gas sensor,
A driving DC motor, an eccentric member fixed in an eccentric state to the output shaft of the driving DC motor, a diaphragm made of an elastic member, a distal end portion connected to the eccentric member, and a base end portion fixed to the diaphragm In the normal driving state, the driving DC motor is driven to rotate in the forward rotation direction so that the diaphragm is reciprocated, and when the driving DC motor is stopped, the amount of distortion of the diaphragm is small. Configured to stop at low distortion positions,
When starting the drive DC motor, a preliminary drive process for driving the drive DC motor in the reverse direction and a DC drive motor stopped by the preliminary drive process at a normal rotation drive voltage with a torque equal to or less than the maximum drag force of the diaphragm. In the preliminary driving process, the driving DC motor is driven with a reverse driving voltage smaller than the normal driving voltage, and the diaphragm is first subjected to the distortion amount of the diaphragm in the normal driving process. It is characterized by being deformed in a direction opposite to the maximum deformation direction.

  In the diaphragm pump device of the gas detector of the present invention, it is preferable that the eccentric member has a balance weight portion.

  Further, in the diaphragm pump device of the gas detector of the present invention, when the normal driving process following the preliminary driving process is not continuously performed and the driving DC motor is not rotated, the preliminary driving process and the subsequent normal driving process are performed again. The driving process can be performed.

The portable explosion-proof gas detector of the present invention comprises the above diaphragm pump device,
A battery is used as the driving power supply, and power from the battery is supplied to the diaphragm pump device via the current limiting means.

  According to the diaphragm pump device of the gas detector of the present invention, when the driving DC motor is started, a preliminary driving process for rotating the driving DC motor in the reverse direction is performed, and the diaphragm is deformed in a predetermined direction. In the normal driving process, since the auxiliary rotational energy that contributes to the rotation in the forward direction due to the elasticity of the diaphragm can be obtained, the forward rotation drive voltage for obtaining the torque required for the drive DC motor itself As a result, it is possible to reduce the power consumption and to save power, and it is possible to reliably obtain a torque exceeding the maximum drag of the diaphragm and to obtain excellent startability.

  Since the eccentric member has the balance weight portion, the startability of the drive DC motor can be further improved by the action of the inertia of the balance weight portion due to the rotation in the forward rotation direction. Stabilization of rotation can be achieved.

  According to the portable explosion-proof gas detector of the present invention comprising the diaphragm pump device described above, it can be configured to satisfy the explosion-proof specification, and the diaphragm pump device can be reliably driven. Gas detection can be performed reliably.

It is a block diagram which shows the outline of a structure in an example of the portable explosion-proof type | mold gas detector provided with the diaphragm pump apparatus of this invention. It is sectional drawing which shows the outline of a structure in an example of the diaphragm pump apparatus of this invention. It is a top view which shows the structure of the head part in the diaphragm pump apparatus shown in FIG. It is a block diagram which shows the outline of a structure of the motor drive control circuit which comprises the power supply circuit in the portable explosion-proof type gas detector shown in FIG. It is a figure which shows the example of control of the motor drive voltage in the motor drive method which concerns on this invention. It is sectional drawing for operation | movement description which expands and shows a part of diaphragm pump apparatus shown in FIG. 2, Comprising: (A) The state in a stop position, (B) The state stopped in the preliminary drive process, (C) Normal drive The state where the drive rod is in the low strain position in the process being performed, (D) the state where the drive rod is in the maximum strain position in the process where the normal drive process is being performed, and (E) the normal drive process is performed. In this process, the drive rod is in the low strain position beyond the maximum strain position. It is an operation | movement flowchart for demonstrating the operation state monitoring operation | movement of the drive DC motor. It is a graph which shows the result of the motor starting property confirmation test in Experimental example 1, Comprising: ((alpha)) shows a current waveform and ((beta)) shows a voltage waveform. It is a graph which shows the result of the motor starting property confirmation test in the comparative experiment example 1, Comprising: ((alpha)) shows a current waveform and ((beta)) shows a voltage waveform.

Hereinafter, embodiments of the present invention will be described in detail.
FIG. 1 is a block diagram showing a schematic configuration of an example of a portable explosion-proof gas detector provided with a diaphragm pump device of the present invention.
This portable explosion-proof gas detector (hereinafter simply referred to as a “gas detector”) includes a driving power source 50 made of a primary battery or a secondary battery (storage battery) such as a dry battery, and a current from the driving power source 50. A power supply circuit 40 that is supplied by being restricted by the restriction element 41, a gas sensor 30 and a gas detection unit 35 comprising a diaphragm pump device 10 for supplying a gas to be detected to the gas sensor 30, and a display for displaying the detected gas concentration A signal processing unit including an operational amplifier 31, for example, which performs appropriate signal processing on the gas detection signal from the gas sensor 30. And a CPU 55 that controls the operation of each component and calculates the gas concentration based on the gas detection signal.
The power supply voltage of the driving power supply 50 is, for example, 3.5V.

  As shown in FIGS. 2 and 3, the diaphragm pump device 10 includes a diaphragm pump 20 and a driving DC motor 11.

  The diaphragm pump 20 includes, for example, a cup-shaped diaphragm 21 that forms a substantially cylindrical or frustoconical internal space, a pump chamber 22 that is provided on the opening side of the diaphragm 21 and defines a pump chamber S, and the diaphragm 21. A rectangular frame-like fixing member 23 that is mounted from the bottom side of the diaphragm and holds and fixes the opening edge of the diaphragm 21, and a gas suction unit that is disposed in contact with the pump chamber 22 via a check valve 26. 27A and a gas discharge part 27B, and a driving rod 15 made of, for example, a resin material having a base end embedded and fixed at the center of the bottom of the diaphragm 21. The fixing member 23, the pump The four corners of the chamber 22 and the head portion 25 are fixed integrally with fixing screws (not shown).

  The diaphragm 21 is made of a rubber material such as ethylene propylene rubber or chloroprene rubber and other elastic bodies, and has a hardness (Shore hardness HS) of, for example, 70 ° (for example, a strain amount when a load of 0.5 N is applied). (The amount of deformation) has a deformability (elasticity) of about 1.7 mm).

  The driving DC motor 11 is screwed in a state where the output shaft 11A protrudes through the plate-like portion 23A in the thickness direction with respect to the plate-like portion 23A formed on the fixing member 23 in the diaphragm pump 20. The eccentric member 13 is fixed to the projecting portion of the output shaft 11 </ b> A in an eccentric state with respect to the output shaft 11 </ b> A of the driving DC motor 11.

The eccentric member 13 is made of, for example, a resin material, and is fitted with a circular eccentric cam portion 13A to be fitted in a state in which a bearing (ball bearing) 12 is interposed in a cylindrical holding portion 15A formed at a tip portion of the drive rod 15. And a balance weight portion 13B formed integrally with the circular eccentric cam portion 13A.
The balance weight portion 13B functions as a “flywheel (flywheel)”, so that the rotational stability of the driving DC motor 11 can be obtained, and the pump startability improvement effect can be obtained.

  The power supply circuit 40 includes a gas detector main body drive circuit 42 that outputs an operation command signal to the display unit 56, the alarm unit 57, and the like, and a motor drive control circuit 45 that outputs an operation command signal to the driving DC motor 11. It has.

  As shown in FIG. 4, the motor drive control circuit 45 supplies, to the drive DC motor 11, a drive voltage controlled to a predetermined magnitude according to, for example, environmental conditions based on an operation command signal from the CPU 55. The drive voltage variable circuit 46 and a bridge circuit composed of four switch elements SW1, SW2, SW3, SW4 each composed of, for example, an FET are provided.

In the motor drive control circuit 45, for example, the first switch element SW1 and the fourth switch element SW4 are both turned on, and the second switch element SW2 and the third switch element SW3 are both turned off. Thus, electric power is supplied (indicated by a one-dot chain line in FIG. 4) so that the driving DC motor 11 is driven in the forward rotation direction.
On the other hand, the first switch element SW1 and the fourth switch element SW4 are both turned off and the second switch element SW2 and the third switch element SW3 are both turned on, so that the drive DC motor is driven. Power supply (indicated by a two-dot chain line in FIG. 4) is performed so that 11 is driven in the reverse direction.

Further, the gas detector includes an operation state monitoring mechanism 38 that detects whether or not the driving DC motor 11 has started normally.
Operating condition monitoring mechanism 38 is configured to detect a change in current flowing through the resistor R _SNS connected to the bridge circuit by four switching elements SW1~SW4 constituting the motor drive control circuit 45 is amplified by an amplifier 39 .

Hereinafter, the operation of the gas detector will be described.
When the power of the gas detector is turned on, the power from the driving power source 50 is supplied through the current limiting element 41, and the constituent members such as the display unit 56 are operated by the gas detector main body drive control circuit 42. At the same time, the diaphragm pump device 10 is started by the motor drive control circuit 45.

  The driving method of the diaphragm pump device 10 will be described in detail. As shown in FIG. 5, after starting the driving DC motor 11, after the preliminary driving process of rotating the driving DC motor 11 in the reverse direction is performed. Then, a normal driving process is performed in which the driving DC motor 11 stopped in the preliminary driving process is rotationally driven in the forward rotation direction.

That is, as shown in FIG. 6 (A), the diaphragm pump device 10 has a low distortion position where the amount of distortion of the diaphragm 21 is 0 or small when the driving DC motor 11 is stopped. The position 15 is stopped at a low strain position downstream in the forward rotation direction from the maximum strain position where the resistance of the diaphragm 21 in the compression deformation process of the diaphragm 21 is maximized. In the process, when the drive DC motor 11 is rotationally driven in the reverse direction, the drive rod 15 moves so that the diaphragm 21 is deformed in the direction in which the pump chamber S is expanded by the cam action of the circular eccentric cam portion 13A of the eccentric member 13. 6B, the resistance of the diaphragm 21 during the expansion and deformation process of the diaphragm 21 It is stopped at a position before reaching the maximum a position. In this state, a reaction force (indicated by a white arrow) in the direction of compressing the pump chamber S is generated due to the elasticity (shape retention) of the diaphragm 21, and the reaction force of the diaphragm 21 is a direct current for driving. In other words, auxiliary rotational energy Td that contributes to rotation when the motor 11 is rotationally driven in the forward rotation direction is provided.
Next, when the driving DC motor 11 is rotationally driven in the normal rotation direction in the normal driving process, the diaphragm accumulated in the preliminary driving process is accumulated in the rotational energy (torque) Tm by the normal driving voltage of the driving DC motor 11 itself. In the state where the auxiliary rotational energy Td due to the elasticity of 21 is added, the drive rod 15 is moved so as to deform the diaphragm 21 in the direction of compressing the pump chamber S by the cam action of the circular eccentric cam portion 13A. The maximum strain position where the drag of the diaphragm 21 is maximized in the compression deformation process of the diaphragm 21 (FIG. 6D) through the low strain position where the strain amount is 0 or small (FIG. 6C) with sufficient momentum. The drive rod so as to deform the diaphragm 21 in the direction of expanding the pump chamber S again. 5 is moved, and the reciprocating motion of the diaphragm 21 reaches the position where the resistance of the diaphragm 21 is maximized in the expansion and deformation process of the diaphragm 21 through the low distortion position (FIG. 6E) where the amount of distortion of the diaphragm 21 is 0 or small. Is continuously performed, and the diaphragm pump device 10 is stably driven.

In the above-described driving method of the diaphragm pump device 10, the normal rotation driving voltage V <b> 2 applied to the driving DC motor 11 in the normal driving process is such that the torque becomes a torque equal to or less than the maximum drag of the diaphragm 21, that is, the maximum of the diaphragm 21. It is set to be smaller than the drive voltage V3 at which a torque equivalent to the drag is obtained.
Specifically, for example, from the viewpoint of power saving and improvement in startability, the normal rotation drive voltage V2 is set to a magnitude that can obtain a torque of 80 to 95% of the maximum drag of the diaphragm 21. The reason why the value is set in such a numerical range is that a driving voltage having a magnitude capable of obtaining a torque exceeding 95% of the maximum resistance of the diaphragm 21 is supplied for the reason of the configuration of the portable explosion-proof gas detector. On the other hand, the driving DC motor 11 cannot be reliably started with a driving voltage having such a magnitude that only a torque smaller than 80% can be obtained.

  Further, the reverse drive voltage V1 applied to the drive DC motor 11 in the preliminary drive step is set to be smaller than the normal drive voltage V2, and is, for example, 65 to 90% of the normal drive voltage V2. By being in such a range, a sufficient amount of auxiliary rotational energy Td can be obtained in the preliminary driving step, and excellent startability can be reliably obtained.

  In the diaphragm pump device 10, whether or not the diaphragm pump device 10 is normally started is monitored by the operation state monitoring mechanism 38, and the normal driving process following the preliminary driving process is not continuously performed. When the driving DC motor 11 is not rotated, the preliminary driving process and the normal driving process are performed again.

  The operation for monitoring the operation state of the drive DC motor 11 will be described in detail. As shown in FIG. 7, when the drive DC motor 11 is started (S1), the preliminary drive step (S2) and the normal operation are continuously performed. A drive process (S3) is performed, and in the normal drive process, a determination process (S4) as to whether or not the drive DC motor 11 has started normally is performed based on the current value detected by the operation state monitoring mechanism 38. .

In this determination process (S4), for example, with reference to FIG. 8, it is detected that the current fluctuation width (the peak value of the current waveform (α)) ΔI is greater than or equal to a certain magnitude, thereby driving. It is determined that the DC motor 11 is normally started, in other words, the drive rod 15 continues to rotate beyond the maximum strain position (D) where the drag of the diaphragm 21 is maximized in the compression deformation process. The test gas is sucked and supplied to the gas sensor 30 (S5).
Here, the magnitude of the current fluctuation width ΔI that serves as a determination criterion varies depending on the magnitude of the normal rotation drive voltage applied to the driving DC motor 11, but for example, when the normal rotation drive voltage is 1.185 V. Can be set to 20 mA.
On the other hand, when the current fluctuation width (the peak value of the current waveform (α)) ΔI is smaller than a certain magnitude, the drive DC motor 11 could not be started, in other words, the drive rod 15 was compressed and deformed. In the process, it is judged that the diaphragm 21 is in the locked state without exceeding the maximum strain position (D) where the drag of the diaphragm 21 becomes the maximum, and then whether the drive DC motor 11 fails due to pump abnormality The determination process (S6) of whether or not is performed based on the number of start failures of the drive DC motor 11.

  In this determination process (S6), when the number of start failures of the drive DC motor 11 is equal to or less than the predetermined number, the preliminary drive step (S2) and the normal drive step (S3) are performed again. . On the other hand, if the number of start failures of the drive DC motor 11 exceeds the predetermined number, it is determined that the diaphragm pump device 10 itself is abnormal (S7), and attention such as inspection is urged. Here, the number of activation failures n as a determination criterion can be set to 10 times, for example.

  As described above, the drive rod 15 is driven from a state where the drive rod 15 is stopped at the low distortion position (E) on the downstream side in the forward rotation direction from the position where the resistance of the diaphragm 21 is maximized in the expansion deformation process of the diaphragm 21 in the forward rotation direction. Even when the DC motor 11 is started, the same motor drive control as described above is performed.

  When the diaphragm pump device 10 is driven by the above driving method and the gas to be detected is supplied to the gas sensor 30, the gas sensor 30 detects the concentration of the detection target gas, and the detection result is displayed on the display unit 56. In addition, when it is detected that the gas concentration exceeds a predetermined value, an alarm operation by the alarm unit 57 is performed.

  Thus, according to the diaphragm pump device 10 configured as described above, the drive rod 15 stops at a low strain position downstream of the maximum rotational position in the forward rotation direction from the maximum strain position where the resistance of the diaphragm 21 in the compression deformation process of the diaphragm 21 is maximum. In this state, when the driving DC motor 11 is started, a preliminary driving process for rotating the driving DC motor 11 in the reverse direction is performed, and the diaphragm 21 is deformed in a direction in which the pump chamber S is expanded. Since the auxiliary rotational energy that contributes to the rotation in the forward rotation direction due to the elasticity of the diaphragm 21 during the normal driving process is obtained, so-called auxiliary rotational energy can be obtained. The forward rotation drive voltage for obtaining the torque required for itself can be reduced to save power. With wear, it is possible to obtain excellent startability to be able to reliably obtain the maximum drag torque above the diaphragm 21.

  Since the eccentric member 13 has the balance weight portion 13B, the startability of the drive DC motor 11 can be further improved by the action of inertia of the balance weight portion 13B due to rotation in the forward rotation direction, and the drive DC motor. 11 can be stabilized.

  According to the portable explosion-proof gas detector provided with the diaphragm pump device 10, it can be configured to satisfy the explosion-proof specification, and the diaphragm pump device 10 can be reliably driven to be expected. Gas detection can be performed reliably.

Hereinafter, experimental examples performed for confirming the effects of the present invention will be described.
A diaphragm pump device was manufactured according to the configuration shown in FIGS. The specification of this diaphragm pump device is as follows.

[DC motor for driving (11)]
Rated voltage: 3VDC
Rated load: 0.196 mN · m,
Rated speed: 3000rpm ± 12%,
Rated current: 65 mA or less,
Maximum drag: 0.175 mN · m
[Diaphragm pump (20)]
Diaphragm (21); Material: EPDM (ethylene propylene rubber), hardness (Shore hardness HS) is 70 °,
Eccentric member (13); Eccentric amount d (stroke amount of drive rod) of circular eccentric cam portion (13A) with respect to output shaft of driving DC motor: 0.65 mm, weight of balance weight portion (13B): 0.3342 g,
Maximum discharge flow rate: 0.6L / min

<Experimental example 1>
The motor drive control circuit shown in FIG. 4 is brought into a state where the drive rod in the diaphragm pump device is stopped at a low strain position downstream of the maximum strain position where the drag force of the diaphragm in the compressive deformation process of the diaphragm becomes the maximum in the forward rotation direction. Thus, the startability confirmation test of the drive DC motor was performed by performing motor drive control in which the preliminary drive process and the normal drive process were continuously performed under the following conditions. The results are shown in FIG. The startability confirmation test was conducted in an environment at 25 ° C.
The reverse drive voltage (V1) in the preliminary drive process is 1.05 V (88.6% of the normal drive voltage (V2)), the reverse drive time is 20 msec, and the normal drive voltage ( V2) is 1.185 V (a magnitude capable of obtaining a torque of about 82.3% of the maximum resistance of the diaphragm).

  As shown in FIG. 8, the fluctuation range ΔI of the current value detected by the operating state monitoring mechanism is about 20 mA (waveform (α)), and the diaphragm pump device is stabilized as shown by the waveform (β). It was confirmed that it can be driven.

<Comparative Experimental Example 1>
In the experimental example 1, the startability of the driving DC motor is the same as that of the experimental example 1 except that the driving DC motor is started by the motor driving control in which only the normal driving process is performed without performing the preliminary driving process. A confirmation test was conducted. The results are shown in FIG.

  As shown in FIG. 9, the fluctuation range of the current value detected by the operation state monitoring circuit is substantially 0 mA (waveform (α)), and the diaphragm pump device is driven as shown by the waveform (β). It was confirmed that the drive motor had stopped.

As described above, according to the motor drive control of Experimental Example 1 according to the present invention, the drive DC motor is started even with a forward rotation drive voltage of 1.184 V, which is a torque less than the maximum drag force of the diaphragm. It was confirmed that power saving can be achieved. The reason for this is that by the rotational drive in the reverse rotation direction in the preliminary drive process, the rotation start position in the forward rotation direction is from the low strain position (stop position) to the maximum strain position where the diaphragm drag is maximized in the diaphragm compression deformation process. Therefore, when rotating in the forward rotation direction, the torque generated by the forward drive voltage of the drive DC motor itself exceeds the shortage of the torque corresponding to the maximum drag of the diaphragm. This is probably because the rotational energy that contributes to the rotation in the forward rotation direction due to the elasticity of the diaphragm corresponding to the torque could be obtained.
On the other hand, in the motor drive control based only on the normal drive process of rotating in the normal rotation direction in Comparative Experimental Example 1, the driving DC motor cannot be started with the normal rotation drive voltage of 1.184V. It was confirmed that the drive voltage required for starting the drive DC motor by the control was 1.440V.

As mentioned above, although embodiment of this invention was described, this invention is not limited to said embodiment, A various change can be added.
For example, the reverse drive voltage, the reverse drive time, the forward drive voltage, and other conditions can be set as appropriate according to the purpose.

DESCRIPTION OF SYMBOLS 10 Diaphragm pump apparatus 11 DC motor for drive 11A Output shaft 12 Bearing (ball bearing)
DESCRIPTION OF SYMBOLS 13 Eccentric member 13A Circular eccentric cam part 13B Balance weight part 15 Drive rod 15A Cylindrical holding part 20 Diaphragm pump 21 Diaphragm 22 Pump chamber 23 Fixing member 23A Plate-like part 25 Head part 26 Check valve 27A Gas suction part 27B Gas discharge Unit 30 gas sensor 31 operational amplifier 35 gas detection unit 38 operation state monitoring mechanism 39 amplifier 40 power supply circuit 41 current limiting element 42 gas detector main body drive circuit 45 motor drive control circuit 46 drive voltage variable circuit 50 drive power supply 55 CPU
56 Display section 57 Alarm section 58 Operation section S Pump chamber SW1, SW2, SW3, SW4 Switch element R _SNS resistance Ra Rotation center

Claims (4)

A diaphragm pump device for supplying a test gas to a gas sensor,
A driving DC motor, an eccentric member fixed in an eccentric state to the output shaft of the driving DC motor, a diaphragm made of an elastic member, a distal end portion connected to the eccentric member, and a base end portion fixed to the diaphragm In the normal driving state, the driving DC motor is driven to rotate in the forward rotation direction so that the diaphragm is reciprocated, and the driving DC motor is stopped so that the amount of distortion of the diaphragm is small. Configured to stop at low distortion positions,
When starting the drive DC motor, a preliminary drive process for driving the drive DC motor in the reverse direction and a DC drive motor stopped by the preliminary drive process at a normal rotation drive voltage with a torque equal to or less than the maximum drag force of the diaphragm. In the preliminary driving process, the driving DC motor is driven with a reverse driving voltage smaller than the normal driving voltage, and the diaphragm is first subjected to the distortion amount of the diaphragm in the normal driving process. A diaphragm pump device for a gas detector, wherein the diaphragm pump device is deformed in a direction opposite to a maximum deformation direction.   The diaphragm pump device for a gas detector according to claim 1, wherein the eccentric member has a balance weight portion.   The normal driving process following the preliminary driving process is not continuously performed, and when the driving DC motor is not rotated, the preliminary driving process and the normal driving process are subsequently performed again. Item 3. A diaphragm pump device for a gas detector according to Item 2. A diaphragm pump device for a gas detector according to any one of claims 1 to 3, comprising:
A portable explosion-proof gas detector, wherein a battery is used as a driving power source, and electric power from the battery is supplied to a diaphragm pump device via a current limiting means.

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