An automotive air conditioning assembly including a scroll compressor and a wrap spring clutch. The wrap spring clutch enables the use of a comparatively smaller pulley (a diameter of at most 85 mm) which comparatively increases the compressor speed and hence cooling capacity at a given engine speed. The clutch requires low power (e.g. less than 5 Watts) for continuous operation.

A variety of brake and/or clutch mechanisms, and improvements thereof, are provided having improved braking power, reduced size and weight, and other benefits. The braking mechanisms include a wrap spring clutch that is operable to mechanically couple a rotating member to a brake rotor that is in consistent contact with a brake pad. Actuation of the wrap spring clutch allows the wrap spring to engage with the rotating member, coupling the rotating member to the brake rotor thus braking the rotating member. The combination of the wrap spring clutch with the brake rotor and pad provides an overall braking mechanism that exhibits the decreased power cost, weight, size, and engagement time of the wrap spring clutch while having a braking power that can be moderated by specifying the area, engagement force, coefficient of friction, or other properties of the brake rotor and pad.

A variety of brake and/or clutch mechanisms, and improvements thereof, are provided having improved braking power, reduced size and weight, and other benefits. The braking mechanisms include a wrap spring clutch that is operable to mechanically couple a rotating member to a brake rotor that is in consistent contact with a brake pad. Actuation of the wrap spring clutch allows the wrap spring to engage with the rotating member, coupling the rotating member to the brake rotor thus braking the rotating member. The combination of the wrap spring clutch with the brake rotor and pad provides an overall braking mechanism that exhibits the decreased power cost, weight, size, and engagement time of the wrap spring clutch while having a braking power that can be moderated by specifying the area, engagement force, coefficient of friction, or other properties of the brake rotor and pad.

In an aspect, an automotive air conditioning assembly comprising a scroll compressor and a wrap spring clutch. The wrap spring clutch enables the use of a comparatively smaller pulley (a diameter of at most 85 mm) which comparatively increases the compressor speed and hence cooling capacity at a given engine speed. The clutch requires low power (e.g. less than 5 Watts) for continuous operation.

In an aspect, a method is provided for controlling a clutch assembly having first and second rotatable clutch members. The method includes providing a wrap spring clutch having first and second ends. The phase angle between the first and second ends determines a diameter of the wrap spring clutch. One of the clutch members is connected with the first end. The method further includes obtaining a target value indicative of a target speed for the second clutch member, and determining through measurement an actual value that is indicative of an actual speed of the second clutch member. The method further includes changing the phase angle between the first and second ends of the wrap spring clutch to generate a selected amount of slip between the wrap spring clutch and the other of the first and second clutch members, based on the target value and the actual value.

In an aspect, an electromechanical apparatus is provided, comprising an electromagnet, a magnetically permeable rotor, a drive, a current source, a current sensor and processing logic. The electromagnet includes a magnetically permeable housing and a wire coil disposed therein. The rotor spins and is disposed in the path of a magnetic circuit generated by the electromagnet. The drive rotates the rotor relative to the electromagnet housing. The rotor and electromagnet housing vary the reluctance therebetween as the rotor rotates. The current source applies a current to the electromagnet coil, wherein, during rotation of the rotor, fluctuations in the current result in the electromagnet coil due to the aforementioned varying reluctance are superimposed on the applied current. The current sensor senses fluctuations in current in the electromagnet coil. The processing logic reads the sensed current and determines the frequency of the fluctuations, which are correlated to rotor speed.

A clutch/brake assembly includes: an input shaft arranged to be rotated, in use, by a motor; an output shaft configured to be rotated by the input shaft when brought into engagement therewith; rotating clutch plate elements configured to transmit torque from the input shaft to the output shaft when engaged; a logarithmic spring mounted around the input shaft; a translating shaft around the spring; an output sleeve between the output shaft and the clutch plate elements; and a solenoid connected to the translating shaft. The solenoid can be in at least two states and either cause movement of the translating shaft to compress the spring in first or second directions control the assembly.

In an aspect, a method is provided for controlling a clutch assembly having first and second rotatable clutch members. The method includes providing a wrap spring clutch having first and second ends. The phase angle between the first and second ends determines a diameter of the wrap spring clutch. One of the clutch members is connected with the first end. The method further includes obtaining a target value indicative of a target speed for the second clutch member, and determining through measurement an actual value that is indicative of an actual speed of the second clutch member. The method further includes changing the phase angle between the first and second ends of the wrap spring clutch to generate a selected amount of slip between the wrap spring clutch and the other of the first and second clutch members, based on the target value and the actual value.

In an aspect, a method is provided for controlling a clutch assembly having first and second rotatable clutch members. The method includes providing a wrap spring clutch having first and second ends. The phase angle between the first and second ends determines a diameter of the wrap spring clutch. One of the clutch members is connected with the first end. The method further includes obtaining a target value indicative of a target speed for the second clutch member, and determining through measurement an actual value that is indicative of an actual speed of the second clutch member. The method further includes changing the phase angle between the first and second ends of the wrap spring clutch to generate a selected amount of slip between the wrap spring clutch and the other of the first and second clutch members, based on the target value and the actual value.