ELECTRONIC SAFETY CONTROL SYSTEM FOR VEHICLE COMPRESSORS

• US 3,686,891 A
• Filed: 09/21/1970
• Issued: 08/29/1972
• Est. Priority Date: 09/21/1970
• Status: Expired due to Term

• Current Assignee: York International Corporation (Johnson Controls International plc)
• Original Assignee: Frank Eugene Wills
• Inventors: Wills, Frank Eugene
• Primary Examiner(s): Perlin, Meyer
• Application Number:
  US05/073,818
• Time in Patent Office: 708 Days
• Field of Search: 62/228,230,244,323,158 123/41.11
• US Class Current: 62/158
• CPC Class Codes: B60H 1/3208 Vehicle drive related control of the compressor drive means, e.g. for fuel saving purposes
• CPC Class Codes: F25D 29/003 for movable devices

Abstract

A control system for decoupling the mechanical drive between a vehicle mounted air conditioning compressor and the vehicle'"'"''"'"'s engine in response to sensed engine speeds beyond a high level.

Claims

1. In a motor vehicle having an engine and an accessory which accessory is selectively drive coupled to the engine and which eNgine develops a pulsating electrical signal proportionate to engine speed the improvement of having an electronic safety control system for governing the engagement of the engine drive to the accessory, comprising:

first means coupled to the engine for developing an electrical signal representative of engine speed including;

a monostable multivibrator coupled for operation to the source of pulsating electrical signals of the engine, and a resistive-capacitive circuit connected to time integrated and average the output of said mono-stable multivibrator; and

second means operatively coupled to said first means for governing the engagement of the engine drive to the accessory in response to the output of said resistive-capacitive circuit when the speed signal reaches a predetermined level.

2. In a motor vehicle having an engine driven refrigeration system, the improvement comprising:

first means for developing electrical signals representative of engine rotational speed;

a source of a reference electrical signals;

a comparator circuit coupled to receive the engine speed signals of said means and the reference signals of said source, to compare said signals and to produce output signals when the engine speed signals reach a predetermined relation with the reference signals said predetermined relationship being representative of a high engine rotational speed;

second means responsive to the output of the comparator circuit to govern the drive of the refrigeration system by the engine, whereby damage or destruction of the refrigeration system from overdriving by the engine is prevented.

3. The improvement as defined in claim 2 for a motor vehicle of the type there set out, wherein:

a source of a second reference electrical signals is provided;

a second comparator circuit operatively coupled to said first means is provided for producing output signals when the speed signal reaches a predetermined low engine speed representative level, which second comparator circuit is also coupled in a logical '"'"''"'"''"'"''"'"'OR'"'"''"'"''"'"''"'"' relationship to said second means to have its output signal to cause said second means to disengage and prevent engagement of the engine and the refrigeration system;

whereby the refrigeration system is not driven when the engine speed is above a first predetermined sensed high speed nor below a selected low speed.

4. An electronic control system for motor vehicles having an engine for driving the vehicle and a refrigeration system also driven from that engine comprising, in combination:

means for producing a voltage signal representative of the speed of the engine;

a monitor coupled to said first means for monitoring the speed signal of said first means and producing an alarm signal when said speed signal reaches a predetermined state, said monitor including means for producing the alarm signal when the speed signal reaches either of two states representing a high engine speed or low engine speed and not for speed signals representing speeds therebetween;

said speed signal producing means including a short on-time monostable multivibrator coupled for triggering by an electrical signal from the engine, and a low pass filter circuit coupled to said multivibrator for integrating and time averaging the output of said multivibrator to produce a d.c. voltage level which level is proportional to engine speed;

a second means coupled to said monitor, for preventing the coupling and for decoupling the refrigeration system from the engine in response to the alarm signal of said monitor;

whereby driving of the refrigeration system by the vehicle engine is prevented at engine speeds wherein such driving would be undesirable.

5. The combination as set out in claim 4 wherein:

said monitor includes a first comparator (31) and a second comparator (32) said first comparator so connected as to produce an output signal whenever the voltage level of said speed signal reaches preselected low level, and said second comparator so connected as to produce an output when the voltage level of said speed signal reaches a preselected high level.

6. The combination as set out in claim 5, wherein:

said output of said first comparator serves to determine the reference voltage input of said second comparator and the output of said second comparator is the alarm signal.

7. The combination as set out in claim 6, wherein:

a time delay circuit (41) for coupling to said second means for delaying the operation of said second means is employed.

8. The combination as set out in claim 6, wherein:

said first and second comparators are matched operational amplifiers with the primary positive input of each of said operational amplifiers connected to receive the speed signal and the primary negative input of said first operational amplifier connected to a predetermined d.c. level voltage and the output of said first operational amplifier connected across a voltage dividing circuit whose output serves as the primary positive input of said second operational amplifier.

9. The combination as set out in claim 4 wherein a tachometer is provided which comprises a voltmeter which is connected to measure the d.c. voltage level speed signal and has its scale graded in engine speed units.