JPH1183566A - Flowmeter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a flowmeter by which a warning signal can be issued quickly by a method wherein a flow-rate detection part is provided, a pressure detection part is provided and the generation of an abnormality in a fluid is detected quickly. SOLUTION: A signal which corresponds to a preset reference flow-rate value Qref and a corrected actual flow-rate detection signal from an F/V converter 32 are input to a comparator 40, both are compared regarding their magnitude, and a first judgment signal is output. In addition, a pressure switch 35 compares an actual pressure vlue P obtained by detecting the pressure of cooling water with a preset reference pressure value Pref regarding their magnitude. When P<Pref a second judgment signal is output to the side of a circuit board. An OR circuit 41 as a warning-signal output part is provided on the circuit board. The first judgment signal is input to the terminal on one side of the OR circuit 41, and the second judgment signal is input to the terminal on the other side. Then, when either the first judgment signal or the second judgment signal is input, the OR circuit 41 immediately outputs a warning signal to a control means 59 which is installed at the outside.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow meter.

[0002]

2. Description of the Related Art Conventionally, there has been known a welding machine for automatically performing resistance welding on a plurality of locations by driving a welding gun three-dimensionally according to a program. In this type of automatic resistance welding machine, the temperature of the welding gun (particularly, the tip portion) is increased by energization. Therefore, it is necessary to cool the welding gun by some cooling system. FIG.
An example is shown below.

[0003] The cooling system 100 comprises a primary pipe 1
01, a secondary side pipe 102, a flow path 103 connecting them, and the like. A welding gun 104, which is a device requiring cooling, is provided in the middle of the flow path 103. The welding gun 104 is provided with a pair of tips 105 that are current-carrying parts. One tip 105 is attached to the fixed side of the gun body 107 by a shank 106.
The other tip 105 is attached to the movable side of the gun arm 108 by the shank 106. The two chips 105 are in a positional relationship facing each other.
A flow path (not shown) for flowing cooling water is formed in the gun body 107. The channel is a shank 10
6, the cooling water is in direct contact with the bottom surface of the chip 105 attached thereto.

Control means 109 constituting an automatic resistance welding machine
The opening / closing control of the gun arm 108 is performed via the gun arm opening / closing drive unit 110. The control means 109 drives the entire welding gun 104 three-dimensionally by the welding gun driving means 111.

A flow meter 121 as shown in FIG. 11 is provided downstream of the welding gun 104 in the flow path 103. This flow meter 121 is a so-called turbine type. The turbine type flow meter 121 is provided with a flow detecting means 12.
2 and an electric circuit unit 123. Flow rate detecting means 122
Has a fixed blade 124, a rotary blade 125, and a stopper 126. The rotary wing 125 located downstream of the fixed wing 124 has a divided flow path 127 of the fixed wing 124.
, It is rotated by the action of the cooling water given a rotational motion. A magnet having substantially the same shape is attached to the rotary wing 125 so as to be integrally rotatable. MR sensor 129
Detects the number of rotations of the rotary wing 125 based on the number of magnetic force changes per unit time, and outputs the detected number to the electric circuit unit 123 as a pulse signal. The electric circuit unit 123 includes an F / V converter 131 for F / V converting the pulse signal.
It has. Then, the electric circuit unit 123 uses the signal obtained by the F / V conversion as a detection signal as a detection signal.
9 is output. The control unit 109 constantly monitors such a detection signal to detect an abnormality (for example, a shortage of the flow rate) of the cooling water flowing in the flow path 103.
In addition, the shortage of the flow rate of the cooling water can be caused by 1) when the flow path 103 is clogged, or
It is known that it occurs when the cooling water leaks from the engine.

Here, in the electric circuit section 123, F / V
In general, an integrator 132 is often provided after the converter 131. Such an integrator 132 integrates the voltage signal from the F / V converter 131 and shapes the waveform so as to be smooth. As a result, the influence of noise and the like is reduced, and the output signal is stabilized.

[0007]

In recent years, this type of automatic resistance welding machine has been required to move the welding gun 104 from a welding point to a welding point as quickly as possible. That is, shortening the tact time when welding one point leads to improvement in productivity.

However, the speeding up of the resistance welding machine causes the following problems. The graph in FIG. 12 shows a temporal change in the actual flow rate of the cooling water and a temporal change in the detection signal output from the flow meter 121 to the outside. According to this, it can be seen that both of them start to decrease at a certain time point t1. However, the manner in which the flow rate of the cooling water actually decreases is considerably sharper than the manner in which the detection signal decreases. Such a difference occurs because the detection signal is integrated. Therefore, a predetermined set value (here, a lower limit value) Q
There is a natural difference between the two before and after the ref. That is, the actual flow rate of the cooling water is equal to the set value Qref.
, The detection signal falls below the set value Qref at a time about 2-3 seconds later than that time.
As described above, the conventional apparatus cannot quickly respond to the occurrence of the abnormality, and cannot immediately take measures such as stopping the apparatus before the welding gun 104 moves to the next welding point.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a flow meter capable of promptly responding to the occurrence of a fluid abnormality and promptly outputting a warning signal to the outside. Is to do.

[0010]

In order to solve the above-mentioned problems, according to the first aspect of the present invention, a flow connecting a primary pipe to which a fluid is supplied and a secondary pipe to which the fluid is discharged is provided. On a road, in a flow meter provided together with equipment that requires cooling, a flow detection unit that detects a flow rate of the fluid, a pressure detection unit that detects a pressure of the fluid, and at least one of a flow value and a pressure value And a warning signal output unit that outputs a warning signal to the outside when the values deviate from the respective set value ranges.

[0011] In the second aspect of the present invention, in the first aspect, the flow rate detection unit includes a fixed blade having a plurality of divided flow paths, and a rotary blade disposed downstream of the fixed blade. ,
Assuming that the turbine is a turbine type flow detecting unit configured to rotate the fixed blade by the action of the fluid given a rotational motion by passing through the divided flow path and detect the flow rate of the fluid based on the number of rotations. I have.

According to a third aspect of the present invention, in the first aspect, the flow rate detector includes a vortex generator for generating a Karman vortex, and a vortex for detecting the Karman vortex downstream of the vortex generator. A Karman vortex-type flow rate detector that has a detector and detects the flow rate of the fluid based on the state of occurrence of the Karman vortex.

According to a fourth aspect of the present invention, in any one of the first to third aspects, a backflow prevention mechanism for preventing a backflow of the fluid is incorporated. According to a fifth aspect of the present invention, in the fourth aspect, the backflow prevention mechanism is a check valve that can be opened and closed only by the inertia of the fluid.

According to a sixth aspect of the present invention, in any one of the first to fifth aspects, a magnet for removing foreign matter is incorporated in the primary port into which the fluid flows. Hereinafter, the “action” of the present invention will be described.

According to the first aspect of the present invention, since both the flow rate detecting section and the pressure detecting section are provided, even when a sudden change occurs in the fluid, the flow rate value can be rapidly reduced. A sharp decrease in the pressure value is detected ahead of time. For this reason, as compared with the conventional apparatus having only the function of detecting the flow rate, it is possible to promptly respond to the occurrence of the abnormality in the fluid and to quickly output the warning signal to the outside.

According to the second aspect of the present invention, since the flow rate detecting section has a rotating portion, it is characterized by being relatively resistant to vibration. Therefore, it becomes suitable for use in an environment with vibration. Another characteristic is that the pressure drop is small and the measurable area is wide.

According to the third aspect of the present invention, since the flow rate detecting portion has no rotating portion, it has a feature that it is resistant to foreign matter such as iron rust. Therefore, it is suitable for use in an environment where foreign matter is likely to be mixed into the fluid.

According to the fourth aspect of the present invention, the backflow prevention mechanism operates to prevent the backflow of the fluid even when the back pressure acts from the secondary side piping. Therefore, leakage of the fluid can be immediately stopped even when the chip comes off.

According to the fifth aspect of the invention, if the check valve can be opened and closed only by the action of the inertia of the fluid,
It can be configured without using a biasing means such as a spring. Therefore, a failure is less likely to occur than in the case where the backflow prevention mechanism is configured using the urging means, and the reliability is excellent. Further, the pressure loss is smaller than that using a biasing means such as a spring. That is, if the urging means such as a spring is used, even when the fluid is flowing normally, the pressing force of the spring always acts in the opposite direction to the flow of the fluid, which causes an increase in pressure loss. is there.

According to the sixth aspect of the present invention, when the fluid passes through the primary port, iron rust contained as foreign matter therein is adsorbed and removed by the magnet. Therefore, it is possible to prevent the iron rust from being clogged in the flow detection unit, and the reliability of the apparatus is improved.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION

[First Embodiment] A flow meter 1 according to a first embodiment of the present invention and a cooling system 50 for a resistance welding machine using the same will be described below in detail with reference to FIGS.

FIG. 1 shows a turbine type flow meter 1 according to this embodiment. The turbine unit housing constituting the turbine type flowmeter 1 is constituted by four blocks of a first block 2, a second block 3, a third block 4, and a fourth block 5. The second block 3 is a cylindrical member having flange portions at both ends.
The first block 2 is fitted to the left end of the second block 3 via an annular packing 6. A third block 4 is fitted to the right end of the second block 3 via an annular packing 6. A fourth block 5 is fitted to the right end of the third block 4 via an annular packing 6. The first block 2 has a primary port 7 for connecting a pipe (not shown). In the fourth block 5, a secondary port 8 for connecting a pipe (not shown) is formed. Cooling water as a fluid flows in from the primary port 7 and flows out from the secondary port 8. When the blocks 2, 3, 4, 5 are connected to each other, the ports 7, 8 communicate with the internal spaces 9 of the second and third blocks 3, 4 to form one flow path. The turbine unit 11 is immovably accommodated in the internal space 9 on the second block 3 side.

On the upper surface side of the second block 3, a cover 12 for accommodating an electric circuit portion is mounted. An MR sensor mounting portion 13 protrudes from an upper surface and substantially in the center of the second block 3. The MR sensor mounting part 13
Is provided with an MR sensor 15 as magnetic sensing means via an annular packing 14. The MR sensor 15 is electrically connected to a circuit board 17 via a lead 16. Various electronic components (light emitting diode 18, trimmer 19, etc.) are mounted on the circuit board 17 by soldering or the like.

Next, the configuration of the flow rate detector will be described. As shown in FIG. 2, the turbine unit 11 is cylindrical, and includes a fixed blade 20, a rotating blade 21, and a stopper 2.
2 and so on. The fixed blade 20 is formed in a part (that is, the bottom) of a cylindrical casing 23 having a bottom, and is located on the most upstream side (inflow side) of the turbine unit 11.
The stopper 22 has a six-blade structure, and is attached to an opening of the casing 23. The rotary wing 21 is accommodated in a space defined by the stopper 22 and the casing 23. The rotor 21 of the present embodiment is a resin member provided with four blade pieces 24. A magnet having substantially the same shape as that of the rotor 21 is attached to the rotor 21 so as to be integrally rotatable. The tip of the rotating shaft 25 at the center of the rotating blade 21 is
0 is supported by a bearing 26 provided at the center of the inner end side. The base end of the rotating shaft 25 is supported by a bearing 27 provided at the center of the inner end side of the stopper 22 via a hard ball 28. Therefore, the rotating shaft 21 downstream of the fixed wing 20
Can rotate around its own rotation axis 25.

As shown in FIG. 2, the fixed wing 20 has a plurality of divided flow paths R. Each of the divided flow paths R is partitioned by curved blade pieces 29. These wings 29
Changes the direction of the cooling water passing through the divided flow path R, thereby giving a rotational motion to the cooling water. The cooling water given a rotational motion by the blade pieces 29
Bring rotation.

The MR sensor 15 constituting the turbine type flow rate detector detects the number of rotations of the rotor blades 21 based on the number of magnetic force changes per unit time, and uses this as a pulse signal (actual pressure signal) to generate a signal F. / V converter 32. The pulse signal from the MR sensor 15 is converted by the F / V converter 32 into a corrected actual flow rate detection signal. Further, the waveform of the signal is shaped by the integration process in the integrator 31. Integrator 31 and F /
The V converter 32 is provided on the circuit board 17 and constitutes a flow rate detection unit together with the turbine unit 11 and the MR sensor 15.

A comparator 40 is provided on the circuit board 17 as first comparing means. Comparator 4
From one input terminal of 0, a signal corresponding to a preset reference flow rate value (lower limit value of the setting range) Qref is input. From the other input terminal of the comparator 40, a corrected actual flow rate detection signal from the F / V converter 32 is input. The comparator 40 compares the magnitudes of the actual flow rate value Q and the reference flow rate value Qref based on these signals.
Is output. That is, when the actual flow rate value Q is equal to or larger than the reference flow rate value Qref (that is, within the set range and does not fall below the lower limit value), the comparator 40 outputs a low level signal. On the other hand, when the actual flow rate value Q is less than the reference flow rate value Qref (ie, deviates from the set range and falls below the lower limit value), the comparator 40 outputs a Hi-level signal.

Next, the pressure detector will be described. FIG.
As shown in FIG. 2, a pressure guiding hole 33 communicating with the inside and outside of the third block 4 is formed on the upper surface of the third block 4. The outside opening of the pressure guiding hole 33 is the pressure switch mounting part 3
4, a pressure switch 35 as a pressure sensing means is attached thereto. That is, in the present embodiment, the pressure detection unit is configured by the pressure guiding hole 33 and the pressure switch 35. The pressure switch 35 is electrically connected to the circuit board 17 via the lead wire 36. The pressure switch 35 detects an actual pressure value P and a preset reference pressure value (lower limit value of the setting range) Pref based on an actual pressure detection signal obtained by detecting the pressure of the cooling water.
Compare large and small. The actual pressure value P is equal to the reference pressure value P.
When it becomes smaller than ref (that is, it falls outside the set range and falls below the lower limit), the pressure switch 35 outputs a second determination signal to the circuit board 17 side. In addition, both pressure values P and Pre
The comparison of f is made by a comparator (not shown) inside the pressure switch 35.

However, the pressure switch 35 is not limited to the electrical type described above, but may be a mechanical type such as a contact type. That is, when the actual pressure value P becomes smaller than the reference pressure value Pref, a simple contact signal may be output to the circuit board 17 as the second determination signal.

The turbine type flowmeter 1 has an OR circuit 41 as a warning signal output unit on the circuit board 17. A first determination signal is input to one input terminal of the OR circuit 41, and a second determination signal is input to the other input terminal. When at least one of these determination signals is input, the OR circuit 41 outputs a warning signal to the control means 59 provided outside.

Next, the overall configuration of the resistance welding machine cooling system 50 using such a flow meter 1 will be described. The cooling system 50 includes a primary pipe 51, a secondary pipe 52, a flow path 53 connecting them, and the like. A welding gun 54 of an automatic resistance welding machine, which is a device requiring cooling, is provided on the way of the flow path 53, and the turbine type flowmeter 1 is provided downstream thereof. Welding gun 5
Reference numeral 4 includes a pair of chips 55 which are current-carrying portions. One tip 55 is attached to the gun body 57 side, which is a fixed side, by a shank 56. The other chip 5
5 is attached to the movable side of the gun arm 58 by the shank 56. The two chips 55 are in a positional relationship facing each other. A flow path (not shown) for flowing cooling water is formed in the gun body 57. Since the flow path bypasses the shank 56, the cooling water comes into direct contact with the bottom surface of the chip 55 attached thereto. Also, the welding gun 54
And a primary side stop valve 62 between the
Is provided, and a secondary stop valve 63 is provided between the welding gun 54 and the secondary pipe 52. A flow path 53 is provided between the primary stop valve 62 and the welding gun 54.
A two-way valve 64 is provided as an electromagnetic valve for switching the state between the open state and the open state.

This automatic resistance welding machine comprises a control means 59, a gun arm opening / closing drive means 60 and a welding gun drive means 61. The control means 59 such as a computer controls opening and closing of the gun arm 58 via the gun arm opening and closing driving means 60. More specifically, the gun arm opening / closing drive unit 60 controls the supply and exhaust of air to and from an air cylinder (not shown) in the welding gun 54. Further, the control means 59 drives the entire welding gun 54 three-dimensionally by the welding gun driving means 61. As a result, the welding gun 54 moves at a high speed from the welding point to the welding point. Further, the control means 59 controls the two-way valve 6
4 is controlled to open and close. Specifically, a solenoid (not shown) in the two-way valve 64 is demagnetized by a control signal from the control means 59.

The OR circuit 4 of the turbine type flow meter 1
When a warning signal is input from No. 1, the control means 59 executes an emergency stop. That is, the control means 59 controls the two-way valve 64
The solenoid is demagnetized by outputting an emergency stop signal. As a result, the flow path 53 is immediately shut off, and the loss of cooling water due to leakage is minimized. Control means 59
Outputs an emergency stop signal to the gun arm opening / closing drive means 60 and the welding gun drive means 61 at the same time.
As a result, the gun arm 58 and the welding gun 54 are immediately stopped.

Next, the operation of the cooling system 50 will be described. When clogging or the like occurs in the flow path 53, usually,
The flow rate of the cooling water gradually decreases. FIG. 4A shows how the actual flow rate Q of the cooling water (after the F / V conversion and the integration processing) at that time changes with time. In this case, the actual flow value Q takes a relatively long time to reach the reference flow value Qre.
reaches f. Then, the actual flow value Q is equal to the reference flow value Qref.
, The OR circuit 41 outputs a warning signal to the control means 59. As a result, the control means 59 immediately executes an emergency stop.

On the other hand, when a chip is missing, the flow rate of the cooling water decreases more rapidly than when the clogging occurs.
FIG. 4B shows the actual flow rate value Q (F / F /
(After V-conversion and integration) is shown over time. In this case, the actual flow value Q reaches the reference flow value Qref within a short time. The graph of FIG. 3C also shows how the pressure of the cooling water changes over time when a chip is missing or the like. In this case, within a shorter time than the flow value Q reaches the reference flow value Qref,
The pressure value P reaches the reference pressure value Pref. In other words, the response of the pressure to the rapid change of the cooling water is better than that of the flow rate. That is, in this case, a sharp decrease in the pressure value P is grasped prior to a sharp decrease in the flow value Q. As a result of the pressure value P reaching the reference pressure value Pref as described above, the OR circuit 41 outputs a warning signal to the control means 59, and the control means 59 immediately executes an emergency stop.

Now, the characteristic effects of this embodiment will be listed below. (A) The turbine type flow meter 1 according to the present embodiment includes not only the turbine type flow detection unit but also a pressure detection unit. Also,
The turbine type flow meter 1 is configured to output a warning signal to the outside when at least one of the flow value Q and the pressure value P falls below each of the reference values Qref and Pref. Therefore, as compared with the conventional device having only the function of detecting the flow rate, it is possible to quickly respond to the occurrence of the abnormality of the cooling water (particularly, the chip missing). Therefore, a warning signal can be output to the outside promptly, and the emergency stop of the welding gun 54 and the like can be executed quickly. therefore,
The apparatus can be stopped before the welding gun 54 moves to the next welding point.

(B) Since the flow meter 1 of the present embodiment is a turbine type flow meter 1 having a flow detecting portion of a type having a rotating portion, it is of a type which detects a flow rate using a vortex of a fluid. It has a feature that it is more resistant to vibration than. Therefore, even when used in an environment with vibration, for example, in a state of being attached to the welding gun 54 driven at a high speed, there is no possibility that the detection accuracy will be deteriorated. Therefore, it is very suitable for use under such conditions. In addition, since this turbine type flow meter 1 is a so-called straight turbine type, it has an advantage that pressure loss is extremely small and also has an advantage that a measurable area is wide. Second Embodiment Next, a flow meter 71 of a second embodiment and a resistance welding machine cooling system 70 using the same will be described in detail with reference to FIGS. The same components as those of the first embodiment are denoted by the same reference numerals instead of omitting the detailed description.

FIG. 5 shows a turbine type flow meter 71 of this embodiment. This turbine type flow meter 71 is different from the turbine type flow meter 1 of the first embodiment in that a check valve 72 as a backflow prevention mechanism is incorporated.

As shown in FIG. 6, this check valve 7
Reference numeral 2 includes a flow path plate 73, a rubber sheet 74, a backflow prevention plate 75, and a retaining ring 77. A plurality of communication holes 73a are formed in a disc-shaped base 73c that forms the flow path plate 73. These communication holes 73a communicate with both side surfaces of the base 73c. A tubular portion 73b is provided at the center of one side surface of the base 73c. A columnar shaft portion 75b is vertically provided at the center of one side surface of the disk-shaped base portion 75a constituting the backflow prevention plate 75. The shaft portion 75b is a cylindrical portion 7
It is formed somewhat longer than 3b. Rubber sheet 7
Reference numeral 4 denotes a donut-shaped member having a through hole in the center, which is adhered to the side surface of the base 75a protruding from the shaft. The shaft portion 75b is slidably inserted into the insertion hole of the cylindrical portion 73b. Shaft portion 75b protruding from cylindrical portion 73b
An E-shaped retaining ring 77 is mounted at the end of the head with a margin of a certain length. The presence of the retaining ring 77 prevents the shaft portion 75b from coming out of the tubular portion 73b when the backflow prevention plate 75 slides.

As shown in FIG. 5, the third block 4
The check valve 72 is provided at the joint of the fourth block 5 and the fourth block 5.
The valve installation part 76 for installing this is provided. In the valve installation portion 76 having a large diameter, the backflow prevention plate 75 is located on the secondary port 8 side, and the flow path plate 73 is connected to the primary port 7.
The check valve 72 is arranged so as to be located on the side. In addition, the base 73c of the flow path plate 73 is
5 is fixed to the valve installation portion 76 in such a manner as to be sandwiched between the valve installation portions 76.

When the pressure of the cooling water at the primary port 7 is relatively higher than the pressure of the cooling water at the secondary port 8, the cooling water tends to flow from the primary port 7 to the secondary port 8. I do. At this time, the backflow prevention plate 75 is moved in the direction of the secondary port (to the right in FIG. 5) by the inertia of the cooling water, so that the rubber sheet 74 is
Separate from c. Therefore, at this time, the check valve 72 is opened, and the cooling water can flow through each communication hole 73a.

Conversely, when the pressure of the cooling water at the primary port 7 is relatively lower than the pressure of the cooling water at the secondary port 8, the cooling water flows from the primary port 8 to the secondary port 7. Try to flow. At this time, as a result of the inertia of the cooling water, the backflow prevention plate 75 moves in the direction of the primary port (the leftward direction in FIG. 5), so that the rubber sheet 74 is pressed against the base 73c and closes each communication hole 73a. .
Accordingly, at this time, the check valve 72 is closed, and the cooling water cannot flow through the respective communication holes 73a. That is,
The backflow prevention mechanism operates to prevent backflow of the cooling water.

Now, the characteristic effects of the present embodiment will be enumerated below. (A) The present embodiment does not differ from the first embodiment in the basic configuration, and it is needless to say that the functions and effects a and b enumerated in the first embodiment are achieved.

(B) Check valve 72 as backflow prevention mechanism
In the turbine type flow meter 71 of the present embodiment, the check valve 72 operates to prevent the backflow of the cooling water even when the back pressure acts from the secondary pipe 52. Therefore, even when chips are missing, leakage of the cooling water can be immediately stopped.

(C) Since the check valve 72 of this embodiment can be opened and closed only by the inertia of the cooling water, it can be constructed without using a biasing means such as a spring. Therefore, a failure is less likely to occur than in the case where the backflow prevention mechanism is configured using the urging means, and the reliability is excellent. If the spring is included as a component, the spring may be displaced due to, for example, vibration of the device, which may cause a failure. In view of such a point, the turbine type flow meter 71 of the present embodiment is provided with a welding gun 54 driven at high speed.
It is extremely suitable for use in a state in which it is attached to. Further, if the configuration is such that the urging means such as a spring is not used as in this embodiment, the pressure loss can be reduced. [Third Embodiment] Next, a flow meter 81 of a third embodiment and a resistance welding machine cooling system 80 using the same will be described in detail with reference to FIG. The components common to the first embodiment and the like are denoted by the same reference numerals instead of omitting the detailed description.

The features of this turbine type flow meter 81 are that the same check valve 72 as that of the second embodiment is provided, and that the configuration of a pressure switch 83 as a pressure detector is slightly different. The pressure switch 83 used here detects the pressure of the cooling water and outputs the actual pressure detection signal to the comparator 8.
Output to 2.

Comparator 82 as second comparing means
Is provided on the circuit board 17. Comparator 8
From one of the two input terminals, a signal corresponding to a preset reference pressure value (lower limit value of the setting range) Pref is input. An actual pressure detection signal is input from the other input terminal of the comparator 82. Comparator 82
Compares the magnitudes of the actual pressure value P and the reference pressure value Pref based on these signals, and outputs a second determination signal. That is, when the actual flow value P is equal to or larger than the reference flow value Pref (that is, within the set range and does not fall below the lower limit), the comparator 82 outputs a low-level signal to the OR circuit 41. On the other hand, when the actual flow value P is less than the reference flow value Pref (that is, the actual flow value P falls outside the set range and falls below the lower limit value), the comparator 82 outputs a Hi-level signal to the OR circuit 41.

When at least one of these judgment signals is input, the OR circuit 41 outputs a warning signal to the control means 59 provided outside, and the control circuit 5
9 executes an emergency stop.

The operation and effects characteristic of the present embodiment will be listed below. (A) This embodiment also has the same basic effects as those of the first embodiment. Similarly, the present embodiment including the check valve 72 also has the operation and effect b and c listed in the second embodiment. Fourth Embodiment Next, a flow meter 86 of a fourth embodiment and a resistance welding machine cooling system using the same will be described in detail with reference to FIG. The components common to the first embodiment and the like are denoted by the same reference numerals instead of omitting the detailed description.

The features of this turbine type flow meter 86 are that it has the same check valve 72 as in the second embodiment, and that it incorporates a magnet 88 for removing foreign matter. The magnet 88 is an annular permanent magnet, and is fixed to an annular mounting groove 87 on the inner wall surface of the primary port 7. Therefore, the cooling water flowing from the primary side port 7
8 and then flow into the turbine unit 11.

The operation and effects characteristic of the present embodiment will be listed below. (A) This embodiment also has the same basic effects as those of the first embodiment. Similarly, the present embodiment including the check valve 72 also has the operation and effect b and c listed in the second embodiment.

(B) Further, according to the present embodiment in which the magnet 88 for removing foreign matter is built in, when the cooling water passes through the primary port 7, iron rust contained as foreign matter therein is removed by the magnet 88.
Is adsorbed and removed. For this reason, iron rust may be clogged in the turbine unit 11,
It is also possible to prevent the rotation of the motor from becoming impossible due to the bitten iron rust. Therefore, a failure is less likely to occur, and the reliability of the device is surely improved. [Fifth Embodiment] Next, a flow meter 91 of a fifth embodiment and a resistance welding machine cooling system using the same will be described in detail with reference to FIG. The components common to the first embodiment and the like are denoted by the same reference numerals instead of omitting the detailed description.

The features of the flow meter 91 are that it has the same check valve 72 as that of the second embodiment, and that the flow rate detector is not a turbine type but a Karman vortex type. The detection unit 99 constituting the Karman vortex flow rate detection unit has a cylindrical overall shape. The detection unit 99 includes a vortex generator 97 and a vortex detector 98. The vortex generator 97 is a rod having a substantially trapezoidal cross section, and is provided substantially at the center of the flow path in the detection unit 99. The vortex generator 97 plays a role of generating Karman vortices. A vortex detector mounting portion 96 is formed downstream of the vortex generator 97, and a part of the vortex detector 98 is mounted so as to protrude therefrom. As the vortex detector 98, for example, a piezoelectric element or the like is used. In this case, the magnitude and period of the pressure fluctuation caused by the Karman vortex generated by the vortex generator 97 are converted into an electric signal by the piezoelectric element.

The vortex detector 98 is electrically connected to the circuit board 17 through the lead wire 16 and outputs a pulse signal (actual pressure signal) to the F / V converter 32. The pulse signal is processed by the F / V converter 32,
It is converted into a corrected actual flow rate detection signal. Further, the signal is subjected to integration processing in the integrator 31 to be shaped. The integrator 31 and the F / V converter 32 together with the detection unit 99 constitute a Karman vortex flow rate detection unit. That is, in the Kalman flow meter 91 of the present embodiment, the flow rate of the cooling water is detected based on the occurrence state of the Karman vortex. Other points are the same as in the first embodiment.

The characteristic effects of the present embodiment will be listed below. (A) The Karman vortex flow meter 91 includes not only the Karman flow rate detection unit but also a pressure detection unit. The flow meter 91 is configured to output a warning signal to the outside when at least one of the flow value Q and the pressure value P falls below each of the reference values Qref and Pref. Therefore, as compared with the conventional device having only the function of detecting the flow rate, it is possible to quickly respond to the occurrence of the abnormality of the cooling water (particularly, the chip missing). Therefore, a warning signal can be output to the outside promptly, and the emergency stop of the welding gun 54 and the like can be executed quickly. Therefore, it is possible to stop the apparatus before the welding gun 54 moves to the next welding point.

(B) The present embodiment provided with the check valve 72 also provides the operation effects b and c listed in the second embodiment. (C) Since the flow meter 91 of the present embodiment is provided with the Karman vortex type flow rate detecting unit having no rotating part, it has a feature that it is originally resistant to foreign matter such as iron rust. Therefore, it is suitable for use in an environment in which foreign matter is likely to be mixed in the cooling water, for example, in a state where an iron-based pipe is connected. Further, since the flow meter 91 has a built-in magnet 88 for removing foreign substances, iron rust contained in the cooling water is adsorbed and removed. Therefore, the detection unit 99 can be prevented from being clogged with iron rust, thereby improving the reliability of the apparatus.

It should be noted that the present invention is not limited to the above-described embodiment, but can be changed to another form as follows, for example. In the first embodiment without the check valve 72, a two-way valve 64 is also provided between the turbine type flow meter 1 and the secondary stop valve 63, and the control means 59 controls the two-way valve 64 when the chip comes off. May be closed. With such a configuration, even when a back pressure is applied, the loss of cooling water due to leakage can be minimized.

A type different from the check valve 72 exemplified in the third embodiment, for example, the backflow prevention plate 7
Instead of 5, a type using a check ball may be adopted as the backflow prevention mechanism. Further, a check valve that can be opened and closed by the action of a spring force or the like instead of the action of the inertia of the cooling water can be employed as the backflow prevention mechanism.

In the first embodiment, the check valve 72
It is also permissible to provide such a backflow prevention mechanism separately from the turbine type flow meter 1 and to attach it externally to the flow meter 1. ◎ The magnetic sensing means that constitutes the turbine type flow detector
The present invention is not limited to only the MR sensor 15 exemplified in the first to fourth embodiments, but may be another type. Further, a sensing means for detecting the number of rotations by a method not relying on a magnetic force change may be used.

The installation location of the check valve 72 is not limited to the vicinity of the secondary port 8. Therefore, it may be installed upstream of the turbine unit 11 and the detection unit 99. However, even in this case, the check valve 72 needs to be disposed downstream of the pressure detection unit such as the pressure switch 35. When a back pressure is applied to the secondary pipe 52, even if the primary side of the pressure switch 35 is opened, the pressure of the switch portion may not completely decrease due to the back pressure, and it may not be possible to reliably detect chip detachment or the like. It is.

◎ Pressure switch 35 as pressure sensing means
Other than these may be used. The warning signal output unit outputs a warning signal to the outside when at least one of the actual flow rate value Q and the actual pressure value P falls below the lower limit values Qref and Pref as in the first to fifth embodiments. It is not limited to. For example, a warning signal may be output to the outside when at least one of the flow rate value Q and the pressure value P exceeds each upper limit value. Alternatively, a warning signal may be output to the outside when the value deviates from the range of the set value including the lower limit and the upper limit.

The flow path in the welding gun 54 is
In the case where each flow path is individually provided, two flow meters 1, 71, 81, 86, and 91 as in the first to fifth embodiments may be used, and these may be connected to each flow path in a separate system.

The present invention may be embodied not only in a resistance welding machine cooling system but also in a cooling system for other equipment requiring cooling (such as a vacuum dry pump).

Here, in addition to the technical ideas described in the claims, the technical ideas grasped by the above-described embodiments are listed below together with their effects. (1) The actual flow rate detection signal obtained by detecting the fluid flow rate is expressed as F
A flow detection unit that outputs a corrected actual flow detection signal after the / V conversion and integration processing, a pressure detection unit that detects the pressure of the fluid and outputs an actual pressure detection signal, and First comparing means for comparing the actual flow value with a preset reference flow value, and outputting a first determination signal when the actual flow value is lower than the reference flow value; Second comparing means for comparing the magnitude of the actual pressure value and a preset reference pressure value based on the second comparison signal, and outputting a second determination signal when the actual pressure value is lower than the reference pressure value; and And a warning signal output unit that outputs a warning signal to the outside when at least one of the first determination signal and the second determination signal is input. With this configuration, it is possible to promptly respond to the occurrence of an abnormality in the fluid and quickly output a warning signal to the outside.

(2) F / V conversion and integration processing of the actual flow detection signal obtained by detecting the flow rate of the fluid, and a flow detecting section for outputting a corrected actual flow detection signal, and detecting the pressure of the fluid. The actual pressure value is compared with a preset reference pressure value based on the actual pressure detection signal obtained in step 2, and a second determination signal is output when the actual pressure value is lower than the reference pressure value. A pressure detector, compares the magnitude of the actual flow value and a preset reference flow value based on the corrected actual flow detection signal, and generates a first determination signal when the actual flow value falls below the reference flow value. A first comparing unit that outputs a warning signal; and a warning signal output unit that outputs a warning signal to the outside when at least one of the first determination signal and the second determination signal is input. And flow meter. With this configuration, it is possible to promptly respond to the occurrence of an abnormality in the fluid and quickly output a warning signal to the outside.

(3) The flowmeter according to claims 4 or 5, wherein the pressure detector is located downstream of the flow detector, and the backflow prevention mechanism is located downstream of the pressure detector. With this configuration, the detection can be reliably performed even when the back pressure is applied. (4) The check valve according to claim 5, wherein the check valve is provided on the flow path plate in which the communication hole is formed, and the shaft portion is inserted into a cylindrical portion of the flow path plate. A backflow prevention plate that is relatively movable; a rubber sheet attached to the backflow prevention plate and capable of closing the communication hole; and a backflow from the flow passage plate, which is attached to a tip of a shaft portion of the flow passage plate. A flow meter comprising a retaining ring for preventing the prevention plate from coming off. With this configuration, the backflow prevention plate moves in a predetermined direction by the action of the inertia of the fluid, so that the rubber sheet separates from and comes into contact with the flow path plate, so that the check valve can be reliably opened and closed.

(5) A device that requires cooling is provided on a flow path connecting a primary pipe to which a cooling fluid is supplied and a secondary pipe from which the cooling fluid is discharged, and a downstream side of the device is provided. The flowmeter according to any one of claims 1 to 6 is arranged, an electromagnetic valve is provided between the primary pipe and the device, and the electromagnetic valve is set based on a warning signal from the flowmeter. A cooling system comprising a closing control means. With this configuration, the flow path is immediately shut off by closing the solenoid valve, so that the loss of the cooling fluid due to leakage can be minimized.

(6) In the technical idea 5, the equipment requiring cooling is an automatic resistance welding machine having a welding gun, and the control means is an emergency stop for the gun arm opening / closing driving means and the welding gun driving means. A resistance welding machine cooling system configured to output a signal. With this configuration, the gun arm and the welding gun can be immediately stopped when a chip comes off or the like.

The technical terms used in this specification are defined as follows. "Fluid: refers to liquids such as water and oil used for cooling, etc., and also includes gases such as nitrogen, oxygen and carbon dioxide."

[0070]

As described above in detail, according to the first to sixth aspects of the present invention, the flow rate which can promptly respond to the occurrence of an abnormality in the fluid and promptly output a warning signal to the outside. Meter can be provided.

According to the second aspect of the present invention, it is possible to provide a flow meter which is suitable for use in an environment having vibration, has a low pressure loss, and has a wide measurable area. According to the third aspect of the present invention, it is possible to provide a flow meter suitable for use in an environment in which foreign matter is likely to be mixed into a fluid.

According to the fourth aspect of the present invention, even when a chip comes off, the leakage of the fluid can be immediately stopped, and the loss of the fluid can be minimized. According to the fifth and sixth aspects of the present invention, it is possible to improve reliability and reduce pressure loss.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a flow meter according to a first embodiment of the invention.

FIG. 2 is a partially broken perspective view showing a turbine unit of the flow meter of FIG.

FIG. 3 is a block diagram showing a resistance welding machine cooling system using the flow meter of FIG. 1;

FIG. 4 (a) shows a temporal change in the actual flow rate of the cooling water when clogging or the like occurs, and FIG. 4 (b) shows a temporal change in the actual flow rate of the cooling water when a chip comes off or the like;
(C) is a graph showing how the actual pressure value of the cooling water changes with time when a chip is missing or the like.

FIG. 5 is a sectional view showing a flow meter according to a second embodiment.

6 is an exploded perspective view of a check valve in the flow meter of FIG.

FIG. 7 is a block diagram illustrating a resistance welding machine cooling system using the flow meter of FIG. 5;

FIG. 8 is a block diagram showing a resistance welding machine cooling system using the flow meter according to the third embodiment.

FIG. 9 is a cross-sectional view illustrating a flow meter according to a fourth embodiment.

FIG. 10 is a sectional view showing a flow meter according to a fifth embodiment.

FIG. 11 is a sectional view showing a conventional flow meter.

FIG. 12 is a graph for explaining the relationship between the temporal change of the actual flow rate of the cooling water and the temporal change of the detection signal output from the flow meter to the outside.

FIG. 13 is a block diagram showing a conventional resistance welding machine cooling system using a flow meter.

[Explanation of symbols]

1, 71, 81, 86: Turbine flow meter, 7: Primary port, 11: Turbine unit which is a part of turbine type flow detector, 15: MR sensor which is a part of turbine type flow detector, 20 ... fixed wing, 21 ... rotating wing, 31 ... integrator which is a part of the flow detecting unit, 32 ... F / V converter which is a part of the flow detecting unit, 33 ... pressure guiding hole which constitutes a pressure detecting unit, 35, 83 ... pressure switches constituting a pressure detection unit,
41: OR circuit as a warning signal output unit, 50, 70,
80 (resistance welding machine) cooling system, 51 ... primary side piping, 52 ... secondary side piping, 53 ... flow path, 54 ... welding gun of resistance welding machine as equipment requiring cooling, 59 ... control means, 72 ... check valve as backflow prevention mechanism, 88 ...
Magnet, 91: Karman vortex flow meter, 97: vortex generator, 9
Reference numeral 8 denotes a vortex detector, 99 denotes a detection unit which is a part of the Karman vortex flow rate detection unit, and R denotes a divided flow path.

Continued on the front page (72) Inventor Masatsugu Sato 3005 Hayasaki, Kokugaiyama, Komaki City, Aichi Prefecture Inside CK Corporation

Claims (6)

[Claims] 1. A flowmeter provided with a device requiring cooling on a flow path connecting a primary pipe to which a fluid is supplied and a secondary pipe from which the fluid is discharged, wherein a flow rate of the fluid is detected. A flow detection unit, a pressure detection unit that detects the pressure of the fluid, and a warning signal that outputs a warning signal to the outside when at least one of the flow rate value and the pressure value deviates from the range of each set value. A flow meter comprising an output unit. 2. The apparatus according to claim 1, wherein the flow rate detection unit includes a fixed blade having a plurality of divided flow paths and a rotating blade disposed downstream of the fixed blade. 2. The flow rate according to claim 1, wherein the flow rate of the fluid is a turbine type flow rate detection unit configured to rotate the fixed wing by the action of the fluid given the flow rate and detect the flow rate of the fluid based on the rotation speed. Total. 3. The flow rate detecting section includes a vortex generator for generating a Karman vortex, and a vortex detector for detecting the Karman vortex downstream of the vortex generator, wherein the Karman vortex is generated. The flow meter according to claim 1, wherein the flow meter is a Karman vortex flow rate detection unit configured to detect a flow rate of the fluid based on a situation. 4. The flowmeter according to claim 1, further comprising a backflow prevention mechanism for preventing a backflow of the fluid. 5. The flowmeter according to claim 4, wherein the backflow prevention mechanism is a check valve that can be opened and closed only by the inertia of the fluid. 6. The apparatus according to claim 1, wherein a magnet for removing foreign matter is built in the primary port into which the fluid flows.
The flow meter according to any one of claims 1 to 4.