Wobble plate type refrigerant compressor provided with an internal rotation detector generating a signal having a symmetrical wave form

A variable capacity wobble plate type refrigerant compressor comprising:

• a housing having therein a suction chamber for a refrigerant to be compressed and a discharge chamber for a compressed refrigerant,
• a cylinder block having therein a plurality of cylinder bores in which reciprocatory pistons are disposed to pump in the refrigerant from the suction chamber and then to discharge the refrigerant after compression to the discharge chamber,
• a crankcase connected to the cylinder block and defining a crank chamber therein receiving therein a drive shaft axially extending through an inner end wall of the crankcase;
• a generally circular support element mounted on the axial drive shaft to be rotatable with the drive shaft, and having a base disc portion having a predetermined diameter, a support arm radially projecting from the base disc portion into the crank chamber, and a partial balancing rim portion in the form of a partial circular extension provided for a part of an outer circumference of the base disc portion to have a diameter larger than the predetermined diameter of the base disc portion;
• a first thrust bearing arranged between the inner end wall of the crankcase and the support element for supporting the support element;
• a rotary drive plate pivotally connected to the support arm of the support element to be rotatable with the support arm and capable of changing an inclination thereof with reference to a plane perpendicular to an axis of the axial drive shaft;
• a non-rotatable wobble plate held by the rotatable drive plate via a second thrust bearing so as to change an inclination thereof with the drive plate, the wobble plate being operatively connected to the reciprocatory pistons via piston rods to cause a reciprocatory compressing motion of the pistons;
• a control valve means for regulating a pressure level in the crank chamber with respect to a suction pressure prevailing in the suction chamber of the housing so as to control a pressure differential between the pressure in the crank chamber and the suction pressure to thereby regulate the inclination of the wobble plate;
• and
• a rotation detector for generating an electric signal indicating that internal elements of the compressor including the support element, and the rotatory drive plate are rotated by the drive shaft, the rotation detector comprising:
• a flanged disc-like sensed element arranged between the inner end wall of the crankcase and the support element, the sensed element being provided with a disc portion having a diameter larger than that of the partial balancing rim portion of the support element, and a flange extending axially from an outer periphery of the disc portion to thereby enclose the support element, the flange of the sensed element being formed therein with apertures, each being arranged to be located at a position other than that lying on an outer periphery of the partial balancing rim portion of the support element;
• and
• a sensing element arranged at a fixed position adjacent to the surface of the flanged disc-like sensed element enclosing the support element and cooperating with the sensed element for generating a rotation detecting signal when the apertures of the sensed element passes the sensing element.