JPH0246794B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a swash plate compressor, and particularly to a rotational speed detection device thereof.

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 were sometimes damaged. In particular, in the case of a compressor for vehicle air conditioning, it has recently been designed to drive all of the water pump, alternator, compressor, etc. of the vehicle drive engine with a single belt. When the belt breaks due to the inability to rotate, the engine overheats, which has the inherent defect of causing a serious vehicle accident.

In view of the above-mentioned deficiencies, the present invention provides a relatively highly sensitive rotational speed detection device for monitoring the operating state of a compressor, particularly a swash plate compressor, thereby more reliably protecting the power source and related equipment. It was done for that purpose. The present invention will be explained in detail below based on the illustrated embodiments.

In FIG. 1 showing the overall configuration of a swash plate compressor, a pair of cylinder blocks 1 and 2 facing each other have an appropriate number of cylinder bores 4 parallel to a drive shaft 3 extending through the center thereof. It is perforated. A ball 6 is mounted on the swash plate 5 which is fixed to the drive shaft 3 at an angle.
A piston 8 is moored via a bearing device consisting of a shoe 7 and a shoe 7, and the piston 8 can reciprocate within the cylinder bores 4, 4 by the rotational force of the swash plate 5. 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 housings 11,1
A suction chamber 13 and a discharge chamber 14 are formed in each of the valve plates 9 and 10, and these suction chambers 13 and discharge chambers 14 communicate with an external refrigeration circuit, respectively. 1
It communicates with the cylinder bores 4, 4 via 6. Although not shown, reed valves are provided at each of the suction port 15 and the discharge port 16. Next, the rotational speed detecting device of the present invention will be described in detail with reference to FIG. 2, which is a cross-sectional view of a main part showing a cross section in a part different from the cross section in FIG.
A swash plate 5 that swings within the swash plate 3 is made of a magnetic material (for example, a ferrous metal material), and the circumferential portion of the swash plate 5 itself constitutes a detected portion. An electromagnetic sensor 18 is disposed on the outer shell of the cylinder block 1 at the maximum tilt position of the swash plate. The electromagnetic sensor 18
is composed of a main body 19, a magnet 20 held by the main body 19, and a coil 21 surrounding the magnet 20. Note that the magnet 20 is disposed such that its tip end face directly faces the maximum inclination position of the swash plate. The coil 21 is connected by a lead wire 22 to an external control device such as an amplifier or a pulse presence/absence detector.

When the drive shaft 3 connected to a power source by an electromagnetic clutch (not shown) rotates, the swash plate 5 fixed thereto rotates, causing the piston 8 to reciprocate within the cylinder bores 4, and A compression action of the compressed fluid is performed. Due to the rotation of the drive shaft 3, the detected part consisting of the circumferential part of the swash plate 5 moves on a periodic motion locus, and the magnetic flux formed between the magnet 20 and the detected part made of a magnetic material. The density changes when the detected part faces the magnet 20, so a current is generated in the coil 21 surrounding the magnet 20 at that time. After amplifying the voltage of the current with an amplifier and observing it with an oscillograph, the 8th
As shown in the figure, voltage pulses (one positive and one negative for each rotation of the drive shaft 3) are generated at a period corresponding to the rotational speed of the drive shaft 3. 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, since the moving distance of the detected part is relatively large and the periodic movement speed thereof is also relatively large, the change in the magnetic flux density becomes clearer and larger, and therefore the generated pulse signal also The above control can be performed relatively accurately since it is less susceptible to the influence of noise. 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.

In the above-described embodiment, the electromagnetic sensor 18 was disposed at a position facing the detected portion at the position where the swash plate 5 was tilted to the maximum toward the cylinder block 1, but the present invention is limited to this embodiment. Instead, it is also possible to arrange them at similar positions on the cylinder block 2 side.

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 the pulse presence/absence detector detects when the pulse signal becomes null, thereby causing compression. Since it is possible to detect an abnormal stop of the machine and immediately disconnect from the drive system, it is possible to protect the drive system and related equipment.As a result, when applied to vehicle air conditioning, it is possible to It has the remarkable effect of being able to prevent serious vehicle accidents and damage, and also because the swash plate as the detected part makes a relatively large movement and the electromagnetic sensor is placed at the maximum tilt position of the swash plate. Because they are placed facing each other, the change in magnetic flux density becomes clearer and larger, and the generated pulse signal is less susceptible to noise and is easier to detect. Since the electromagnetic sensor can be installed using the appropriate space, it can be carried out without any expansion of the compressor, and there is no need for any processing to form the detected part, and the swash plate itself can be used as is. It also has the effect of being able to.

[Brief explanation of the drawing]

The figures show an embodiment of the present invention, in which Fig. 1 is a sectional front view showing the entire swash plate compressor, Fig. 2 is a sectional view showing main parts in a cross section different from Fig. 1,
FIG. 3 is a graph showing pulses, and FIG. 4 is an explanatory diagram showing the operating mode of the control device. 1, 2...Cylinder block, 3...Drive shaft,
4... Cylinder bore, 5... Swash plate, 8... Piston, 13... Suction chamber, 18... Electromagnetic sensor, 20
...Magnet, 21...Coil.

Claims (1)

[Claims] 1. In a swash plate type compressor in which a piston moored to a swash plate fixed to a drive shaft at an angle is reciprocated within a cylinder bore by the rotational force of the swash plate, the circumference of the swash plate is covered. An electromagnetic sensor serving as a detection unit and disposed facing the maximum tilt position of the swash plate, and a pulse signal emitted by the electromagnetic sensor in response to a change in magnetic flux density caused by the movement of the swash plate. 1. A rotational speed detection device for a swash plate compressor, comprising a pulse presence/absence detector for detecting the presence or absence of a pulse, and detects the rotational state of the compressor.