JPS6123511B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a swash plate compressor, and more particularly to a device for detecting the rotational speed of a compressor.

When the compressor is connected to a power source and becomes unable to rotate due to an accident such as seizure of sliding parts, this creates resistance and places a load on the drive system.
As a result, the power source and related equipment may be damaged. In particular, in the case of a compressor for vehicle air conditioning, in recent years it has been designed to drive all of the water pump, oil generator, compressor, etc. of the vehicle drive engine with a single belt. When the belt is cut due to the inability to rotate, the engine overheats, resulting in a serious vehicle accident.

Therefore, in order to eliminate the above-mentioned defects, a convex part is formed at the rear end of the drive shaft as a detected part, and an electromagnetic sensor is installed opposite to this convex part, or the outer periphery of the swash plate is used as a detected part. An electromagnetic sensor is installed opposite a part of the periodic motion locus of the detected part, and the electromagnetic sensor generates compression by a pulse signal generated in response to a change in magnetic flux density caused by the movement of the detected part. A device that detects the rotational speed of the machine has been proposed. However, in the former case, there is a problem in that the drive shaft diameter is small, that is, the movement distance of the convex part is small, so the change in magnetic flux density is not very large, and the generated pulse signal is therefore small. The compressor is superior in that the movement distance of the outer circumference, which is the detected part, is relatively large, so the pulse signal is less susceptible to noise and more accurate.However, in recent compressors, the swash plate is made of aluminum to reduce weight They tend to be manufactured from alloys, so the latter type of swash plate has the drawback that it cannot be used with a non-magnetic aluminum swash plate.

The present invention has been made in view of the above-mentioned problems, and can be applied to a compressor equipped with an aluminum alloy swash plate by forming a ring-shaped magnetic material around the outer periphery of the swash plate. The objective is to provide a rotational speed detection device with relatively high sensitivity, thereby reliably protecting the power source and related equipment.

Embodiments of the present invention will be specifically described below based on the drawings. First, the embodiment shown in FIGS. 1 and 2 will be described. As shown in the figure, a pair of cylinder blocks 1 and 2 of a centrally divided type facing each other are shown.
A suitable number of cylinder bores 4, 4 are bored through the center of the cylinder parallel to the drive shaft 3. A piston 8 is held on the swash plate 5 which is tilted and fixed to the drive shaft 3 via a bearing device consisting of a pawl 6 and a shoe 7.
It is possible to reciprocate and slide within the cylinder bores 4, 4 by the rotational force of. The end faces of the cylinder blocks 1, 2 are hermetically sealed by front and rear housings 11, 12 disposed with valve plates 9, 10 interposed therebetween. The front and rear housing 1
1 and 12 have a suction chamber 13 and a discharge chamber 1, respectively.
4 are formed, and these suction chamber 13 and discharge chamber 1
4 are in communication with an external refrigeration circuit, respectively, and with cylinder bores 4, 4 via inlets 15 and discharge ports 16 formed in valve plates 9, 10. Although not shown, reed valves are provided at each of the suction port 15 and the discharge port 16.

Next, to explain in detail the rotational speed detection device which is the main part of the present invention, the swash plate 5 that swings in the swash plate chamber 24 is made of a non-magnetic material such as an aluminum alloy, and the swash plate 5 is made of a non-magnetic material such as an aluminum alloy. The iron-based metal ring 1 is used as the magnetic material constituting the detected part.
7 is fitted. On the other hand, an electromagnetic sensor 18 is disposed on the cylinder blocks 1 and 2 at a position periodically facing a part of the ferrous metal ring 17. In this embodiment, the electromagnetic sensor 18 is assembled to the mating surfaces of both cylinder blocks 1 and 2, and is opposed to the axial center of the rotation locus of the ferrous metal ring 17. 17
The swash plate 5 faces each other twice in one rotation. The electromagnetic sensor 18 includes a case 19, a magnet 20 held by the case 19, and a coil 21 surrounding the magnet 20.
and an elastic cylinder 22 made of rubber or the like fitted to the outer periphery of the case 19, and is fitted and held in a circular hole 23 formed in the mating surfaces when the cylinder blocks 1 and 2 are butted together. . Note that the coil 21 is connected to an external control device by a lead wire.

This embodiment is configured as described above,
Therefore, when the drive shaft 3 connected to a power source by an electromagnetic clutch (not shown) rotates, the swash plate 5 fixed thereto rotates, thereby causing the piston 8 to reciprocate within the cylinder bores 4. , the compressing action of the fluid to be compressed is performed. Due to the rotation of the drive shaft 3, the ferrous metal ring 17, which is a detected part, moves along a periodic motion locus together with the swash plate 5. The magnetic flux density is such that the axial center portion of the iron-based metal ring 17 faces the magnet 20 (2 times per rotation of the swash plate 5).
When the magnet 20 is rotated, a current is generated in the coil 21 surrounding the magnet 20.
After amplifying the voltage of the current with an amplifier and observing it with an oscillograph, as shown in Fig. 3, voltage pulses (positive and negative pulses per rotation of the drive shaft 3) are generated at a period corresponding to the rotation speed of the drive shaft 3. 2 of each) are generated. Therefore, when the compressor is operating normally, the pulses are generated periodically, but if the compressor stops abnormally due to seizure of sliding parts or damage to parts, the pulses are generated periodically. When the pulse presence/absence detector (see Figure 4) detects that the pulse is no longer present for a set period of time, the detector outputs a signal to cut off the drive input, and the electromagnetic clutch connecting the power source and the drive shaft is activated. By setting the compressor to a released state, the drive input to the compressor can be cut off to protect the drive system and related equipment. At this time, the movement distance of the detected part is relatively large, and
One rotation of the swash plate 5 changes the magnetic flux density of the electromagnetic sensor 17 twice, and when the speed component in the axial direction is at its maximum, it passes in front of the electromagnetic sensor 18, so that the range of change in the magnetic flux density becomes clearer. Therefore, the generated pulse signal is also large and is not easily affected by noise, and since two pulses can be obtained in one rotation, the above control can be performed accurately and with high sensitivity. In addition, although it was explained above that the above-mentioned protective action starts after the compressor has completely stopped, if the rotational speed of the compressor drops abnormally, the above-mentioned pulse signal will not be generated in a clear form. Due to this, the above-mentioned protective action actually starts immediately before the compressor comes to a complete stop.

Additionally, since an iron-based metal ring is provided around the outer periphery of the swash plate, the sliding characteristics with the piston connection part (the concave notch in the center of the piston) made of aluminum alloy are improved, and seizure is prevented. That is, in the case of a swash plate compressor, the piston 8, which is linked to the swash plate 5 through the ball 6 and shoe 7, rotates within the cylinder bore 4 as the swash plate 5 rotates, so the piston is always The end face of the trailing side of the central concave notch may come into sliding contact with the outer periphery of the swash plate. Therefore, if the aluminum swash plate 5 and the aluminum piston 8 come into direct sliding contact, they may weld and seize. However, this problem can be solved by providing a different magnetic material around the outer periphery of the swash plate 5.

Next, another embodiment of the present invention will be described based on FIG. 5. In this embodiment, as shown, Al.
The embodiment shown in the figure is one in which an iron-based sprayed coating 25 is formed as a magnetic material constituting the detected part over the entire circumference of the swash plate 5 made of aluminum alloy.
The same effects as in the case of the iron-based metal ring 17 described above can be obtained.

In the above embodiment, the electromagnetic sensor 18 is disposed at a position facing the axial center of the swash plate 5, but the present invention is not limited to this. It is also possible to arrange the electromagnetic sensor 18 so as to face the maximum inclined position on the front cylinder block 1 side or the rear cylinder block 2 side. In addition, as a magnetic material,
It is not limited to the iron-based metal ring 17 or the iron-based sprayed coating 25, and temperature-sensitive ferrite, magnets, or the like may be used.

As described above, according to the present invention, the electromagnetic sensor generates a periodic pulse signal in relation to the movement of the swash plate, and when the pulse signal becomes null, an abnormal stop of the compressor is detected, Since the connection with the drive system can be immediately released, the drive system and related equipment can be protected, and as a result, when used for vehicle air conditioning, serious vehicle accidents and damage can be avoided. In addition, since the swash plate as the detected part performs a relatively large movement, the protection function can be performed more accurately, and furthermore, the compressor can be spaced appropriately. Since the electromagnetic sensor can be installed using the swash plate, it has the effect of being able to be installed without any expansion of the compressor. By configuring this, it can be applied even when the swash plate is made of a non-magnetic material made of aluminum alloy.

In particular, in the present invention, a magnetic body is formed in a ring shape on the outer periphery of the swash plate to constitute a detected part, and the rotational speed is detected by periodically facing a part of the detected part with an electromagnetic sensor. Therefore, it is no longer necessary to install magnetic materials scattered around the outer circumference of a rotating body whose outer circumferential end rotates along the same circumferential surface as in the past, and its production is greatly simplified. Furthermore, when the electromagnetic sensor is installed facing the detected part, detection is possible as long as it is within the width of the swash plate in the direction of the rotational axis, so there are no restrictions on the installation position of the electromagnetic sensor. Furthermore, by providing a magnetic material all around the outer periphery of the swash plate, it is effective in preventing seizure caused by direct sliding between the piston and the outer periphery of the swash plate that occurs during operation.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a front sectional view showing a swash plate compressor equipped with a rotational speed detection device, FIG. 2 is a side sectional view, and FIG. 3 is a graph showing pulses. FIG. 4 is an explanatory diagram showing the operating mode of the control device, and FIG. 5 is a sectional view of a swash plate showing another embodiment. 1, 2...Cylinder block, 3...Drive shaft,
4... Cylinder bore, 5... Swash plate, 8... Piston, 13... Suction chamber, 17... Iron-based metal ring,
18... Electromagnetic sensor, 25... Iron-based thermal spray coating.

Claims (1)

[Claims] 1. In a swash plate compressor in which a piston hooked to the swash plate reciprocates within a cylinder bore by rotation of a swash plate fixed to the drive shaft at an angle, the compressor is made of non-magnetic material. A magnetic material constituting the detected part is formed in a ring shape on the outer periphery of the swash plate, and a pulse signal is generated by changes in magnetic flux density at a position periodically facing a part of the detected part. A rotation speed detection device for a swash plate compressor equipped with an electromagnetic sensor. 2. The rotation speed detection device for a swash plate compressor according to claim 1, wherein the magnetic body is an iron-based metal ring fitted around the outer periphery of the swash plate. 3. The rotational speed detection device for a swash plate compressor according to claim 1, wherein the magnetic material is an iron-based sprayed coating applied to the outer peripheral surface of the swash plate.