Drive apparatus for auxiliary equipment responsive to a charging generator speed representing signal

#This invention relates to a drive apparatus for the auxiliary equipment of a motor, and more particularly but not exclusively to the case in which the motor is the engine of an automobile.

#In an automobile, engine auxiliary equipment such as charging generators, water pumps, air conditioning compressors, and oil pumps for hydraulic servo steering is belt-driven by a drive pulley mounted on the end of the crankshaft of the engine. This auxiliary equipment is generally designed to be operated at low speeds, and if driven at the same speed as the engine when the engine is running at high speeds, the operation of the equipment would produce considerable power losses. Therefore, means are generally provided for adjusting the rotational speed of the drive pulley for the auxiliary equipment with respect to the rotational speed of the engine so that the auxiliary equipment can be operated at suitable speeds.

#FIG. 1 shows one type of auxiliary equipment drive apparatus which has been proposed in the past. In this apparatus, a rotating input member in the form of a hollow input shaft 1 is directly connected to the crankshaft of an unillustrated engine. A rotating output member in the form of a pulley 2 is rotatably supported on the input shaft 1 and on a stationary plate 3. The pulley 2 comprises a peripheral casing 2a and an end plate 2b which is secured to the casing 2a by screws 2c. The pulley 2 drives a number of pieces of unillustrated auxiliary equipment by belts which are wound around the pulley casing 2a. The end plate 2b is rotatably supported by the input shaft 1 through a ball bearing 4, while the peripheral casing 2a is rotatably supported by the stationary plate 3 through another ball bearing 5. The stationary plate 3 is secured to a stationary portion of the engine by unillustrated bolts which pass through bolt holes 3a formed in the stationary plate 3. A roller bearing 6 is provided between the input shaft 1 and a flange portion of the stationary plate 3 which surrounds the input shaft 1.

#FIG. 1 is a partially cross-sectional side view of a conventional auxiliary equipment drive apparatus.

#FIG. 2 is a block diagram of a control circuit for the conventional apparatus of FIG. 1.

#FIG. 3 is a partially cross-sectional side view of an embodiment of an auxiliary equipment drive apparatus according to the present invention.

#Hereinbelow, one embodiment of an auxiliary equipment drive apparatus according to the present invention will be described will referring to FIGS. 3 through 5 of the accompanying drawings. FIG. 3 shows the mechanical portions of this embodiment. Except for the absence of a pulse pickup 20 and slits 2e in a pulley casing 2a, the mechanical portions of this embodiment are identical to the mechanical portions of the conventional apparatus illustrated in FIG. 1, and accordingly their explanation will be omitted.

#FIG. 4 illustrates a control circuit for controlling the mechanism for adjusting the reduction ratio of the reduction gear 7 shown in FIG. 3. This control circuit comprises elements 21 through 26, and except for the absence of a pulse pickup 20, this control circuit is identical to the conventional one illustrated in FIG. 2. In this embodiment, instead of being connected to a pulse pickup 20, a waveform shaping circuit 21 is electrically connected to an output terminal 35 for one phase of a 3-phase charging generator 30 which is belt-driven by the pulley 2 of the drive apparatus. The charging generator 30 has stator windings 31 wound in three phases, field coils 32, a 3-phase full-wave rectifier 33 which converts the output of the stator windings 31 into direct current, and a constant voltage regulator 34 which maintains the output voltage of the charging generator 30 constant. Output terminal 35 is electrically connected to the stator winding 31 for one phase of the charging generator 30. This output terminal 35 is electrically connected to the waveform shaping circuit 21, and the voltage induced at the output terminal 35 during operation of the charging generator 30 serves as an electrical output signal indicating the rotational speed of the pulley 2.

#When the input shaft 1 is rotated by the unillustrated engine, rotation is transmitted to the pulley casing 2a in the same manner as in the conventional apparatus, and the charging generator 30 and other auxiliary equipment are belt-driven by the pulley 2. The charging generator 30 generates electricity, and a voltage having the waveform illustrated in FIG. 5 is induced at the output terminal 35. This voltage is applied to the waveform shaping circuit 21 as an electrical input signal. If the rotational speed of the charging generator is N rpm, and the number of poles of the charging generator 30 is P, then the frequency f of this output signal in hertz is NP/120. Because the number of poles P is constant, the frequency f of the output signal from the output terminal 35 is directly proportional to the rotational speed N of the charging generator 30, and since the pulley ratio between the pulley 2 and the charging generator 30 is constant, the frequency f is directly proportional to the rotational speed of the pulley 2. This output signal can therefore be used instead of an output signal from a pulse detector 20 to indicate the rotational speed of the pulley 2, and the exciting current of the electromagnetic coil 15a is controlled by the control circuit based on the frequency of the output signal from the output terminal 35 in the same manner as in the conventional control circuit shown in FIG. 2.