JPH08327651A - Flow sensor - Google Patents

Abstract

PURPOSE: To eliminate malfunction of a flow sensor due to attraction and accumulation of magnetic powder to a part between a refrigerant piping and a piston. CONSTITUTION: A piston 4 is provided to be displaced between an initial position and a displacement position in a refrigerant path comprising refrigerant pipings 2, 3, 6 and a magnetic body 7 is provided integrally with the piston 4. A permanent magnet 10 is secured to the outer part of refrigerant pipings 2, 3, 6 at a position corresponding to the displacement position so that magnetic powder is attracted to the magnetic body 7 when the piston 4 is located at the displacement position but not attracted thereto when the piston 4 is located at the initial position. Since the magnetic powder is not attracted constantly to the part between the refrigerant piping and the piston and accumulated thereon, flow condition of refrigerant can be detected accurately for a long term by means of a flow sensor 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow sensor, which is effective when used for detecting lock of a refrigerant pressure compressor of a vehicle air conditioner, for example.

[0002]

2. Description of the Related Art Generally, a refrigerant compressor of an air conditioner for a vehicle is driven by a vehicle engine through a plurality of auxiliary machines (battery charging generators, etc.) and one belt. If it becomes locked for some reason, it will prevent the rotation of other accessories. In addition, the belt rotates while slipping on the pulley of the refrigerant compressor, resulting in burnout cutting.
This may cause a serious failure in which the drive of all other accessories is stopped.

In order to solve such a problem, a flow sensor as shown in FIG. 7 is disclosed in Japanese Utility Model Laid-Open No. 58-141860. The flow state of the refrigerant is detected using this flow sensor, and it is further determined whether the refrigerant compressor is in the locked state or not based on the output state of the electromagnetic clutch. When the refrigerant compressor is in the locked state, the power supply to the electromagnetic clutch of the refrigerant compressor is cut off, and the transmission of power to the refrigerant compressor is stopped.

The structure and operation of this flow sensor will be described below. A piston 4 integrally provided with a permanent magnet 10 is provided in the refrigerant pipe. Spring 8 on piston 4
Is attached to urge the piston 4 against the flow of the refrigerant. When there is no refrigerant flow, the piston 4 is urged by the spring 8 and is stationary, and this is the initial position. When there is a flow of the refrigerant, the piston 4 receives the flow and contracts the spring 8 to move to the displacement position. The reed switch 9 is provided outside the refrigerant pipe corresponding to the initial position. The bypass passage 17 is provided in parallel with the refrigerant pipe so that it is closed when the piston 4 is in the initial position and opened when the piston 4 is in the displaced position.

When there is a flow of refrigerant in the refrigerant pipe, the piston 4 receives the flow and the spring 8 contracts and displaces to the displacement position, so that the reed switch 9 comes into contact with the contact and opens. When there is no flow of the refrigerant in the refrigerant pipe, the piston 4 is biased to the initial position by the spring 8, so that the reed switch 9 comes into contact with the contacts to close the circuit and detects that there is no refrigerant flow.

Then, even though the electromagnetic clutch is in the ON state (the rotational output of the engine is being transmitted to the refrigerant compressor via the electromagnetic clutch), the refrigerant compressor control device keeps the reed switch 9 in the ON state. When reading (no refrigerant flow), the refrigerant compressor control device can determine that the refrigerant compressor is in the locked state, interrupt the power supply to the electromagnetic clutch, and turn off the electromagnetic clutch. .

[0007]

By the way, in the refrigerant pipe, there is magnetic powder (iron powder) generated by sliding abrasion of the compressor shaft and the like. In the above publication,
Since the refrigerant pipe has a permanent magnet, the permanent magnet always has magnetism in the refrigerant pipe, and the magnetic powder is always adsorbed and accumulated around the permanent magnet and the piston having the permanent magnet. Then, due to the magnetic powder present between the piston and the inner wall of the refrigerant pipe, the piston does not work smoothly in the refrigerant pipe, the piston cannot be immediately displaced to the displacement position even if the refrigerant flows, Further, even if the flow of the refrigerant stops, the piston cannot be immediately returned to the initial position, so that the detection of the refrigerant flow state by the flow sensor is delayed.

Further, when the amount of adsorption and accumulation of magnetic powder increases, the magnetic powder becomes clogged between the permanent magnet and the inner wall of the refrigerant pipe, the piston does not move at all, and the flow sensor becomes inoperable. Then, if the piston does not move at all with the bypass passage closed, the refrigerant passage may be completely closed. The present invention has been made in view of the above points, the magnetic powder is adsorbed between the displacement member and the inner wall of the pipe, the displacement member is smoothly operated in the pipe without accumulating, and the refrigerant of the flow sensor The purpose is to accurately detect the flow state over a long period of time.

[0009]

In order to achieve the above object, the present invention employs the following technical means. In the invention according to claim 1, the pipes (2,
3, 6), a displacement member (4) which is displaceable between an initial position and a displacement position inside the pipes (2, 3, 6), and provided integrally with the displacement member (4). A magnetic body (7) provided therein and the pipes (2, 3, 6). When the fluid flows in the pipes (2, 3, 6), the fluid receives the force and the displacement member (4). ) Together with the urging means (8) that contracts to the displacement position and urges the displacement member (4) to the initial position when the fluid does not flow, and outside the pipes (2, 3, 6), and When the magnetic generation means (10) fixed to a position corresponding to the displacement position and the magnetic body (7) are in the initial position together with the displacement member (4), the magnetic body (7) is displaced by the displacement. Magnetic detection means (9) whose output state changes with the member (4) in the displacement position , And wherein the flow sensor comprises a.

According to the second aspect of the invention, the pipes (2, 3, ...) Corresponding to the fixed position of the magnetic field generating means (10).
6) A flow sensor according to claim 2, characterized in that the inner wall is provided with a groove (13). In the invention according to claim 3, the movable detection target member (4) is provided so as to be integrally displaced with the detection target member (4) along with the displacement of the detection target member (4). The magnetic substance (1) which is fixed to a predetermined position in the vicinity of the moving path of the magnetic substance (7) and the detection target member (4) and generates magnetism (1
0) and magnetic detection means (9) whose output state changes due to a change in the amount of magnetism from the magnetic generation means (10) due to the displacement of the magnetic body (7). And

The reference numerals in parentheses of the above-mentioned means indicate the correspondence with the concrete means described in the embodiments described later.

[0012]

According to the first and second aspects of the present invention, most of the magnetism generated by the magnetism generating means is generated when the magnetism generating means is fixed outside the pipe and the magnetic body is in the displaced position. , The magnetic powder is adsorbed to the magnetic material because it is closer to the magnetic material with higher magnetic permeability, but when the magnetic material moves away from the displacement position, the magnetism generated by the magnetic generation means is closer to the magnetic detection. Since it flows to the means and stops flowing to the magnetic body, the adsorbed magnetic powder separates from the magnetic body.

Therefore, since the magnetic powder is not always adsorbed around the displacement member, the magnetic powder does not accumulate between the displacement member and the inner wall of the pipe, the displacement member always operates smoothly, and the fluid is The displacement member is displaced to the displacement position as soon as it flows, and the displacement member immediately returns to the initial position as soon as the fluid flow stops.Therefore, the flow sensor should accurately detect the fluid flow state for a long period of time. You can That is, the delay in the detection of the fluid flow state by the flow sensor,
The risk of inoperability of the flow sensor and complete closure of the piping is eliminated.

According to the second aspect of the present invention, since the groove is provided in the inner wall of the pipe corresponding to the position where the magnetic field generating means is fixed, the magnetism generated by the magnetic field generating means extends to the fluid passage to some extent. Therefore, the magnetic powder may be adsorbed on the inner wall of the pipe, but the magnetic powder can be adsorbed and accumulated in the groove and does not hinder the displacement path of the displacement member. Therefore, the displacement member always operates smoothly.

According to the third aspect of the invention, since the magnetism generating means is fixed at a predetermined position in the vicinity of the movement path of the detection target member, the magnetic body that is displaced integrally with the detection target member is the magnetic generation means. When the magnetic substance approaches the magnetic substance, the magnetic substance flows to the magnetic substance so that the magnetic substance is attracted to the magnetic substance. However, when the magnetic substance moves away from the magnetism generating means, the magnetism flows to the magnetic detecting means and stops flowing to the magnetic substance. The magnetic powder separates from the magnetic substance. Therefore, since the magnetic powder is not always adsorbed around the detection target member, the displacement of the detection target member is not hindered and always operates smoothly, and the position sensor can accurately detect the position for a long period of time. .

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. The flow sensor 1 of the first embodiment is applied to a vehicle air conditioner and detects the flow state of the refrigerant in the vehicle air conditioner. As shown in FIG. 5, the flow sensor 1 is installed between a high-pressure hose 15 which is a passage for a refrigerant discharged from the refrigerant compressor 14 and a refrigerant inlet of a refrigerant condenser 16 in a vehicle air conditioner. Also serves as a joint between the high pressure hose 15 and the refrigerant condenser 16. Therefore, it can be easily provided in the refrigerant passage without using a special connecting means. Here, when the electromagnetic clutch 14a is connected, the refrigerant compressor 14 is adapted to rotate by receiving power from the engine.

The flow sensor 1 will be described in detail below. The housing 2 is made of a non-magnetic metal material such as aluminum and has a first cylinder 2a, a second cylinder 2b having an inner diameter larger than that of the first cylinder 2a, and one end of the second cylinder 2b. It is integrally formed with the extending flange portion 2c. The housing 3 is formed by integrally molding a cylinder 3a and a flange portion 3b located at one end of the cylinder 3a and extending in the radial direction with a nonmagnetic metal material such as aluminum.
The cylinder 3a has the same radius as the first cylinder 2a, and the flange portion 2c has a ring-shaped groove 2d formed on the circumference of the second cylinder 2b and having a radius larger than that of the second cylinder 2b. Is provided.

After the O-ring 6 is housed in the groove 2d, the flange portion 3b and the flange portion 2c are joined by a joining means such as a bolt (not shown). And housing 2
Further, the housing 3 constitutes a refrigerant pipe serving as a refrigerant passage, and the refrigerant pipe is configured such that the center of the cross section of the second cylinder 2b and the center of the cross section of the cylinder 3a coincide with each other. At the other end of the cylinder 3a, a screw 3c is provided,
A screw 2e is provided at one end of a, and the other end of the cylinder 3a is connected to the refrigerant outlet of the high-pressure hose 15 and the one end of the first cylinder 2a is connected to the refrigerant inlet of the refrigerant condenser 16 by a screw. . Accordingly, the flow sensor 1 also serves as a joint that is a pipe that connects the high pressure hose 15 and the refrigerant condenser 16.

The piston 4 is made of a non-magnetic material such as synthetic resin, is a cylindrical member having a bottom plate 4a, and is slidably formed on the inner peripheral surface of the second cylinder 2b. Bottom plate 4a
Is arranged on the downstream side of the flow of the refrigerant, and one circular hole 4b is provided in the central portion of the bottom plate 4a. The magnetic body 7 is an annular member made of a magnetic material, the inner diameter of which is larger than the inner diameter of the piston 4 and the outer diameter of which is the same as the outer diameter of the piston 4, and is formed integrally with the resin piston 4. .

The coiled spring 8 has a housing 2 at one end.
It is locked to the step portion 2f at the central portion, and the other end is locked to the magnetic body 7 formed integrally with the piston 4. This spring 8
Is the piston 4 when there is no refrigerant flow in the refrigerant pipe.
Is brought into contact with the flange portion 3b. Further, even if the amount of the refrigerant flowing through the refrigerant pipe decreases to some extent (about 10 to 20%) from the regular amount, the refrigerant is subjected to the force of the flow to completely shrink. This refrigerant amount is set as a set amount. here,
The position of the piston 4 in the state where the piston 4 is in contact with the flange portion 3b is taken as the initial position and is shown in FIG. Further, the position of the piston 4 in a state where the spring 8 is completely contracted is taken as a displacement position and is shown in FIG.

The guide 5 is made of a non-magnetic material such as a synthetic resin and integrally formed with a cylinder 5a, a bottom plate 5b, and a support rod 5c located on the opposite side of the center of the bottom plate 5b from the cylinder 5a. . The cylinder 5a has an outer diameter such that it can be fitted into the cylinder 3a, the bottom plate 5b is arranged in the cylinder 3a on the downstream side of the flow of the refrigerant, and the bottom plate 5b and the flange portion 3b are positioned on a straight line. Is fitted to.

When the piston 4 is in the initial position, the tip of the support rod 5c reaches the hole 4b, so that the piston 4
Is displaced from the initial position, the tip of the support rod 5c is moved to the hole 4b.
Is formed so as not to reach. Also, the support rod 5c
Is formed to have a thickness that does not completely close the hole 4b as the refrigerant passage when the piston 4 is at the initial position. Further, the bottom plate 5b of the guide 5 is provided with a hole 5d for inflowing the refrigerant in a portion other than the portion where the support rod 5c is fixed. The holes 5d are provided in a large number so that the refrigerant receives the flow resistance as little as possible.

Since the inner diameter of the piston 4 is the same as the inner diameter of the cylinder 3a and many holes 5d are provided, when the refrigerant flows into the piston 4 through the hole 5d, the piston 4 does not receive much flow resistance. Can flow into the interior.
The connector 11 includes a reed switch 9, terminals 9a and 9b of the reed switch 9 made of a conductive metal, terminals 12a and 12b made of a conductive metal, and a permanent magnet 10 made of a non-magnetic material such as synthetic resin.
It is integrally molded by resin molding with 1a and is provided on the outer peripheral portion of the second cylinder 2b corresponding to the displacement position.

The structure and molding method of the connector 11 will be described below. When magnetism flows, the reed switch 9 comes into contact with its contacts as shown in FIG.
When the magnetic field does not flow, the contacts are separated from each other as shown in FIG. 4 to be in the open state, that is, the OFF state. The terminals 9a and 9b of the reed switch 9 are the terminals 12a and 12b.
From the refrigerant compressor controller 18.

The permanent magnet 10 is formed in a rectangular parallelepiped that is thinner than the wall thickness (about 3 to 5 mm) of the second cylinder 2b. The permanent magnet 1 provided on the outer peripheral portion of the second cylinder 2b corresponding to the position of the magnetic body 7 when the piston 4 is in the displaced position.
It is stored in a groove 2g for storing 0. A predetermined mold is arranged on the outer peripheral portion of the second cylinder 2b so as to cover the groove 2g accommodating the permanent magnet 10. The mold has a bottom, and the bottom surface is formed so as to be closely arranged along the outer peripheral surface of the second cylinder 2b.

Then, the reed switch 9 is provided inside the mold.
And both terminals 9a and 9b of the reed switch 9 and the terminals 12a and 12b are kept connected as shown in FIG. , 9b in the mold. In this state, the resin is injected and hardened, and then the mold is taken out to mold the connector 11.

Here, the reed switch 9 is the permanent magnet 1
Although it is arranged in the vicinity of 0, it is arranged so that the distance between the permanent magnet 10 and the reed switch 9 is sufficiently longer than the distance between the magnetic body 7 and the permanent magnet 10. Next, the operation of the first embodiment having the above structure will be described. First, when the driver turns on the air conditioner (not shown),
The electromagnetic clutch 14a is turned on by the refrigerant compressor control device 18 that controls the energization of the electromagnetic clutch 14a (the electromagnetic clutch 14a is connected to the refrigerant compressor 14 and the rotational output of the engine is transmitted to the refrigerant compressor 14). ), The refrigerant is discharged from the refrigerant compressor 14, and the high pressure hose 1
Refrigerant flows into the flow sensor 1 through 5.

If the refrigerant compressor 14 is not locked,
In the flow sensor 1, the guide 5 is filled with a predetermined amount of refrigerant or more.
It flows in from the hole 5d, but until just before the refrigerant flows in,
Since the support rod 5c reaches the hole 4b of the piston 4, the refrigerant passage in the hole 4b is narrowed, and when the refrigerant flows into the hole, flow resistance occurs when the refrigerant passes through the hole 4b of the piston 4, Since the refrigerant applies pressure to the piston 4 by the resistance force, the piston 4 is quickly displaced to the displacement position.

Then, the magnetic body 7 provided integrally with the piston 4 has also moved to the displacement position, and most of the magnetism generated by the permanent magnet 10 is closer to the magnetic body 7 and has a higher magnetic permeability. 7, the magnetism flowing through the reed switch 9 is drastically reduced, and the reed switch 9 is separated from its contact point and opened. That is, it is in the OFF state. When the reed switch 9 is in the OFF state, the refrigerant compressor control device 18 is turned off.
It is output as an FF signal. At this time, the refrigerant compressor control device 18 determines that the refrigerant compressor 14 operates normally and the refrigerant flow is equal to or more than the set amount based on the information that the electromagnetic clutch 14a is ON and the reed switch 9 is OFF. to decide.

Here, when the refrigerant compressor 14 is in the locked state, the refrigerant compressor 14 does not discharge the refrigerant of the set amount or more, and the refrigerant of the set amount or more does not flow into the flow sensor 1. 4 is in contact with the initial position shown in FIG. Then, since the magnetic body 7 provided integrally with the piston 4 is also located at the initial position, the permanent magnet 10
Of the generated magnetic field flows to the reed switch 9 located closer to the reed switch 9, and the contact of the reed switch 9 is closed to close the reed switch 9.
That is, it is in the ON state.

The ON state of the reed switch 9 is output to the refrigerant compressor controller 18 as an ON signal. At this time, in the refrigerant compressor control device 18, the electromagnetic clutch 14a is turned off.
Due to the information that the reed switch 9 is in the ON state in the N state, the refrigerant flow is equal to or less than the set amount even though the rotational output of the engine is transmitted to the refrigerant compressor 14, that is, the refrigerant compressor 14 is Judged to be in the locked state. Then, an OFF signal is output to the electromagnetic clutch 14 a, the electromagnetic clutch 14 a is turned off, the electromagnetic clutch 14 a is separated from the refrigerant compressor 14, and the rotational output of the engine can be prevented from being transmitted to the refrigerant compressor 14.

Therefore, it is possible to prevent the possibility that the rotation of other auxiliary machines may be hindered, the belt may rotate while slipping on the pulley of the refrigerant compressor, and the burnout of the belt may be cut off, or the driving of other auxiliary machines may be stopped. To be done. Further, since the set amount is made smaller than the regular amount to some extent (about 10 to 20%), the refrigerant may leak to some extent as the usage period of the air conditioner becomes longer. There is no risk of making an erroneous decision that the compressor 14 is locked.

Since the permanent magnet 10 is fixed to the outside of the refrigerant pipe, the permanent magnet 10 is generated when there is a preset amount of refrigerant flow, that is, when the magnetic body 7 is in the displaced position. Since most of the magnetism flows to the magnetic body 7 which is near and has a higher magnetic permeability, the magnetic body 7 adsorbs the magnetic powder, but when there is no refrigerant flow, the magnetic body 7 moves away from the displacement position. Since it is displaced to the initial position, the permanent magnet 10
The generated magnetism flows to the reed switch 9 located closer to it, and stops flowing to the magnetic body 7, so that the adsorbed magnetic powder separates from the magnetic body 7.

That is, since the magnetic powder is not always adsorbed around the piston 4, the piston 4 does not accumulate between the piston 4 and the inner wall of the refrigerant pipe, the piston 4 always operates smoothly, and the refrigerant has a predetermined amount or more. As soon as it flows, piston 4
Is displaced to the displacement position, and the piston 4 is returned to the initial position immediately after the flow of the refrigerant is stopped, and the flow state of the refrigerant can be accurately detected by the flow sensor 1 for a long period of time. Therefore, the delay in the detection of the flow state of the refrigerant by the flow sensor 1, the inoperability of the flow sensor 1, and the risk of the refrigerant pipe being completely closed are eliminated.

As a second embodiment, as shown in FIG.
A rectangular groove 13 having a larger area than the bottom surface of the permanent magnet 10 is provided at a position corresponding to the permanent magnet 10 on the inner wall of the cylinder 2b. By the way, in the first embodiment, the magnetism generated by the permanent magnet 10 flows to some extent in the refrigerant passage, and there is a possibility that magnetic powder may be adsorbed to the inner wall of the housing 2 to some extent. However, in the second embodiment, since the magnetic powder can be adsorbed and accumulated in the groove 13, the passage through which the piston 4 is displaced is not obstructed. Therefore, the piston 4 always operates smoothly.

Although the permanent magnet 10 is used as the magnetism generating means in the above embodiments, an electromagnetic coil or the like may be used instead. Although the reed switch 9 is used as the magnetic detection means, a hall element or the like may be used instead. In the above embodiments, the flow sensor that detects the flow state of the fluid has been described, but the present invention can be widely used in general position sensors that detect the position of a member that moves by mechanical force.

[Brief description of drawings]

FIG. 1 shows a first embodiment of the present invention and is a cross-sectional view of a flow sensor when a piston is in a displacement position.

FIG. 2 is a sectional view of the flow sensor when the piston is in the initial position according to the first embodiment of the present invention.

FIG. 3 shows the first embodiment of the present invention and is a diagram showing an operating state of the reed switch when the piston is at the initial position.

FIG. 4 shows the first embodiment of the present invention and is a diagram showing an operating state of the reed switch when the piston is at the displacement position.

FIG. 5 shows a first embodiment of the present invention, and is a layout diagram in which a flow sensor is applied to a refrigeration cycle of an air conditioner.

FIG. 6 is a sectional view showing a second embodiment of the present invention.

FIG. 7 is a sectional view of a conventional flow sensor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Flow sensor, 2 ... Housing, 2a ... 1st cylinder, 2b ... 2nd cylinder, 3 ... Housing, 4 ... Piston, 5 ... Guide, 7 ... Magnetic material, 8 ... Spring, 9 ... Reed switch, 10 …permanent magnet.

Claims (3)

[Claims] 1. A pipe forming a passage through which a fluid flows, a displacement member provided inside the pipe so as to be displaceable between an initial position and a displacement position, and a magnetic member provided integrally with the displacement member. A body, which is provided inside the pipe, receives the force when the fluid flows in the pipe, contracts with the displacement member to the displacement position, and biases the displacement member to the initial position when the fluid does not flow. Urging means, magnetic generation means fixed outside the pipe and at a position corresponding to the displacement position, when the magnetic body is in the initial position together with the displacement member, and the magnetic body is the A flow sensor comprising: a magnetic detection unit that changes its output state when the displacement member and the displacement member are in the displacement position. 2. The flow sensor according to claim 2, wherein a groove is provided in the inner wall of the pipe corresponding to the fixed position of the magnetic field generating means. 3. A displaceable detection target member, a magnetic body provided so as to be integrally displaced with the detection target member along with the displacement of the detection target member, and a movement of the detection target member. A magnetism generating means fixed to a predetermined position near the path for generating magnetism; and a magnetism detecting means having an output state changed by a change in the amount of magnetism from the magnetism generating means due to the displacement of the magnetic body. Position sensor characterized in that