GB2156906A

GB2156906A - Fluid compressor

Info

Publication number: GB2156906A
Application number: GB08504623A
Authority: GB
Inventors: Minoru Ito
Original assignee: Sanden Corp
Current assignee: Sanden Corp
Priority date: 1984-02-24
Filing date: 1985-02-22
Publication date: 1985-10-16
Also published as: FR2560299A1; IT1183405B; GB2156906B; AU3899885A; IT8519610A0; FR2560299B1; CA1259972A; DE3506063C2; SE8500880D0; DE3506063A1; JPS60178985A; SE459754B; SE8500880L; GB8504623D0

Abstract

A fluid compressor, e.g. of the rotary scroll type or of the swashlate reciprocating-piston type, includes a mechanism for detecting the number of the rotations of the compressor. Magnetic flux, which leaks from an electromagnetic clutch 32 through a main drive shaft 2 to an asymmetric rotating member 26 located within the compressor housing, is sensed by a magnetic pickup 7 which is mounted and supported adjacent the rotation locus of the asymmetric rotating member. The magnetic pulses thereby produced in the pickup are representative of the number of rotations of the compressor. <IMAGE>

Description

SPECIFICATION Fluid Compressor The invention relates to a compressor for an automotive air conditioner including a rotational speed detecting device.

In an automotive air conditioning compressor, when its rotation is stopped by locking, e.g., of the wraps, the connection between a driving source and the compressor should be quickly turned off. If the compressor, an alternator and other equipment are driven together by a V-shaped belt, it is necessary that the movement of the other equipment is not effected when the compressor is stopped. Because of this need, rotational speed detecting devices have been attached to automotive compressors.

It is generally known that there are various types of rotational speed detecting devices for use with compressors; for example mechanical types, generator types, electromagnetic induction types, and so on. These typical rotational speed detecting devices are either placed ahead of the clutch or project behind a compressor, thereby increasing the space required for a compressor. But, since the available space for an automotive air conditioner is limited, it is difficult to attach such a rotational speed detecting device.

Furthermore, a new method for detecting rotation speed is required in compressors of the type, where a main shaft doesn't pass through the rear of the compressor housing. For example, in a scroll type compressor the main shaft does not extend through the rear of the compressor housing so the rotational speed of such a compressor cannot be detected at the rear end of the shaft, which is located inside the housing.

It is the object of the invention to provide a compressor with a rotational speed detecting device which is attached inside the compressor so that the size of the compressor is not increased.

The present invention is directed to a fluid compressor. The compressor includes a housing, a main drive shaft rotatably supported in the housing, and an electromagnetic clutch mounted on the compressor housing for selectively coupling the main drive shaft to an external driving source. A compressing element is drivingly coupled to the main drive shaft, and an asymmetric rotating member is located in the housing and coupled to the main drive shaft for rotary motion and for receiving magnetic flux leading from the electromagnetic clutch through the main drive shaft. A detecting mechanism detects the number of rotations of the compressing element.The detecting mechanism comprises a magnetic pickup connected to the housing and has a portion located adjacent to the rotation locus of the assymetric rotating member to sense the variations of magnetic flux as the asymmetric rotating member rotates past the magnetic pickup.

The invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a sectional view of a scroll type compressor illustrating an embodiment of the invention.

Figure 2 is a sectional view of a magnetic pickup used in an embodiment of the invention.

Figure 3 is a view of an asymmetrical rotor and magnetic pickup, illustrating the electromagnetic induction operation of the invention.

Figure 4 is a view illustrating the voltage change caused by the magnetic pickup in Figure 3.

Figure 5 is a sectional view of a compressor illustrating another embodiment of the invention.

Referring to the attached drawings, in Figure 1, there is shown a scroll type compressor with a housing 1 comprised of a front end plate 11 and a cup shaped portion 12. A hole 111 penetrates front end plate 11 and main drive shaft 2 extends into hole 111, a disk rotor 21 is fixed to the inner end of main drive shaft 2, and is rotatably supported by a bearing 13in hole 111.

Front end plate 11 has a sleeve 14 extending from it which surrounds main drive shaft 2. A bearing 15 is placed in the front end of sleeve 14to rotatably support main drive shaft 2.

A clutch rotor 31 is rotatably supported by a bearing 16, and an electromagnet 32 is fixed on the outer surface of sleeve 14. Armature plate 33 is elastically supported on the end of main drive shaft 2 projecting from sleeve 14. An electromagnetic clutch is thereby comprised of clutch rotor 31, electromagnet 32 and armature plate 33. The rotation from an outer driving source (for example, an automotive engine) is transmitted to main drive shaft 2 through the electromagnetic clutch. More specifically, the rotation from the outer driving driving source is transmitted to clutch rotor 31 through a belt; and thereafter, when armature plate 33 is connected to clutch rotor 31 by turning on electricity to electromagnet 32, the rotation is transmitted from clutch rotor 31 to armature plate 33, and therefrom to main drive shaft 2.

The opening of cup shaped portion 12 is closed by front end plate 11. An orbiting scroll 24 is rotatably supported through a bearing 23 on a driving disk 22 eccentrically connected to the inner end surface of disk rotor 21. A fixed scroll 25 interfits with orbiting scroll 24 and the end plate of fixed scroll 25 is fixed in cup shaped portion 12. A rotation preventing mechanism, which prevents the rotation of orbiting scroll 24, is is comprised of a fixed ring 112, an orbiting ring 113 and balls 114. Fixed ring 112 is fixed to front end plate 11, and orbiting ring 113 is fixed to the end plate of orbiting scroll 24 and faces fixed ring 112. Balls 114 set are placed between both rings and carried within ball receiving holes in each ring.

The fluid which enters at suction port 4 is taken in a closed space which is formed by orbiting scroll 24 and fixed scroll 25, gradually compressed, moved to the center of the both scrolls by the orbital motion of orbiting scroll 24, discharged from output port 51 to discharge chamber 5, and circulated from discharge port 6.

A half disk shaped counterweight 26, which is formed of a magnetic substance, is coupled to the driving mechanism at a location between disk rotor 21 and driving disk 22; more specifically, counterweight 26 is attached to driving disc 22.

Referring to Figure 2, a structure of a magnetic pickup 7 in accordance with the present invention is shown. Magnetic pickup 7 has a coil 73 carried in a core 72. An iron core 71 is inserted through the center of core 72. Coil 73 is attached to core 72, and core 72 is attached to iron core 71 by an epoxy resin 74. Magnetic pickup 7 is inserted into a penetrating hole through front end plate 11 in the direction of an arrow shown in Figure 2. The penetrating hole is pre-formed in front end plate 11. The distal end of iron core 71 is shaped to align substantially flush with the inner surface of front end plate 11 at which it terminates.

Referring to Figure 3, the operation of rotation speed detecting device is explained as follows: Whenever electromagnet 32 is turned on by electricity, main drive shaft 2 is magnetized by the leakage of magnetic flux, and half disk shaped counterweight 26 also is magnetized. Though counterweight 26 moves with the rotation of driving disk 22, the movement of counterweight 26 is the same as rotary motion about the center 28 of main shaft 12, since driving disk 22 is eccentrically coupled to main drive shaft 2 through a drive pin.

Driving pin 22 in turn is coupled to orbiting scroll 24 in such a manner that each rotation of driving disc 22/counterweight 26 results in one orbital revolution of orbiting scroll 24. The distal end of magnetic pick up 7 is located adjacent to and facing the rotation locus of counterweight 26, i.e., adjacent the outermost area through which counterweight 26 rotates.

The magnetic flux () which passes through magnetic pickup 7, since half disk shaped counterweight 26 is magnetized, is at a high level when the A-B-A' portion of half disk shaped counterweight 26 is close to magnetic pickup 7, and is at low level when this portion is not close to magnetic pickup 7. As a result, the magnetic flux which passes through magnetic pickup 7 is changed by the rotation of half disk shaped counterweight 26, and the voltage shown in the following formula (1) is generated in magnetic pickup 7 by electromagnetic induction.

(1) dt When half disk shaped counterweight 26 shown in Figure 3 rotates in the direction of the illustrated arrow, the magnetic flux () which passes through magnetic pickup 7 is reduced as point A' passes pick up 7, and a positive voltage is generated in magnetic pickup 7 according to formula (1). Similarly, a negative voltage is generated at pickup 7 as point A passes it. That is, each time half disk shaped counterweight 26 rotates once, one pulse of positive voltage and one pulse of negative voltage shown in Figure 4 are generated in magnetic pickup 7.

Accordingly, if the number of pulses are measured, the number of compressor rotations can be detected. Because of its half-disc shape, counterweight 26 functions as an asymmetric rotating member to generate the electrical pulses in pickup 7 which are correlated to the rotation1 orbiting of scroll 24, the compressing element.

Figure 5 shows an embodiment of the invention wherein a magnetic pickup 7 is incorporated into a swash plate type compressor. A cam rotor 8, which is inclined on one end surface is rotated by the rotation of main drive shaft 2. A piston 10 reciprocates with the sway of a swash plate 9 which is coupled to the inclined plane of cam rotor 8.

A projection 81 radially projects from the outer circumference of cam rotor 5. Projection 81 extends around a portion of the circumference of cam rotor 8, so that it has end points similar to end points A and A' of counterweight 26. Cam rotor 8 is thus asymmetric and functions as in asymmetric rotating member so that the magnetic flux sensed by pickup 7 varies in the same manner during rotation of cam rotor 8 as during rotation of counterweight 26.

Magnetic flux at cam rotor 8, of course, results from the leakage of magnetic flux when electromagnet 32 is turned on. The rotation of the compressor drive in this embodiment is thus sensed in a manner similar to that of the first embodiment wherein a magnetic pickup to placed adjacent a rotating asymmetric member within the compressor housing.

As mentioned above, the fluid compressor in accordance with the present invention is equipped with an asymmetric rotating member which is substantially magnetized by the electromagnetic clutch, and a magnetic pickup is placed adjacent the rotation locus of the asymmetric rotating member within the compressor housing. The magnetic flux which passes through the magnetic pickup is changed by the substantial variation of distance between portions of the asymmetric member and the magnetic pickup. The rotation of compressor's compressing element thus can be detected by measuring the voltage which is generated in the magnetic pickup. Thus, a large space for a sensor in the compressor is not required and it is easy to mount on an automobile. The number of rotations of the compressor can be very precisely detected since the number of output pulses from the magnetic pickup is generated in accordance with the rotation of main shaft.

This invention has been described in detail in connection with the preferred embodiments, but these are examples only and the invention is not restricted thereto. It will be easily understood, by those skilled in the art that other variations and modifications can be easily made within the scope of this invention.

Claims

1. Afluid compressor comprising a housing, a main drive shaft rotatably supported in the housing, an electromagnetic clutch mounted on said compressor housing for selectively coupling said main drive shaft to an external driving source, a compressing element drivinglycoupled to said main drive shaft an asymmetric rotating member located in said housing and coupled to said main drive shaft for rotary motion and for receiving magnetic flux leaking from said electromagnetic clutch through said main shaft drive, and detecting means for detecting the number of rotations of said compressing element, said detecting means comprising a magnetic pickup connected to said housing and having a portion located adjacent to the rotation locus of said asymmetric rotating member to sense the variations of magnetic flux as said asymmetric rotating member rotates past said magnetic pickup.

2. The fluid compressor of claim 1 wherein said asymmetric rotating member is a counterweight for balancing the centrifugal force of the rotating portions of said compressor.

3. Fluid compressor of claim 2 wherein said compressor is a scroll type compressor.

4. Fluid compressor of claim 1 wherein said asymmetric rotating member is a cam motor.

5. Fluid compressor of claim 4 wherein said compressor is a swash plate type compressor.

6. In a fluid compressor wherein a compressing element carried in a compressor housing is driven by the rotary motion of a main drive shaft which is selectively coupled to an external drive source through an electromagnetic clutch and an asymmetric rotating member is located within the housing, is coupled to the main drive shaft and receives magnetic flux leaking from the electromagnetic clutch through the main drive shaft, the improvement comprising detecting means located at least partially within the compressor housing for detecting the number of rotations of said compressing element, said detecting means comprising a magnetic pickup connected to said housing and having a portion located adjacent to the rotation locus of said asymmetric rotating member to sense the variations of magnetic flux as said asymmetric rotating member rotates past said magnetic pickup.

7. Afluid compressor constructed, arranged and adapted to operate substantially as hereinbefore described with reference to, and as illustrated in, the accompanying drawings.