US3135908A - Control device - Google Patents

Description

J. L. HARRIS CONTROL DEVICE June 2, 1964 Filed March 28, 1962 JMvwk/orl fa 4 A FINAL RESE T United States Patent 3,135,908 CONTROL DEVICE John L. Harris, 4753 N. Newhall St., Milwaukee, Wis. Filed Mar. 28, 1962, Ser. No. 183,194 7 Claims. (Cl. 318-476) This invention relates in general to automatic controls and more particularly to timing controls for use with air conditioners and other types of refrigeration systems.

In compression type refrigeration systems a substantial pressure differential is developed by the compressor when it runs. 'When the compressor is stopped, this pressure differential equalizes in a short period of time so that it is relatively easy to start the compressor for the next cycle. However, if the compressor is started before this equalization takes place an excessive starting torque is required.

One object of the invention is to provide a unitary control device which can be interposed between the compressor and its automatic control such as a thermostat and which insures that the compressor cannot be started until the predetermined time has elapsed after stopping the compressor.

A further object of the invention is to provide a unitary control device which delays the starting of a compressor for a short time after the thermostat or other condition responsive device calls for cooling.

Another object of the invention is to provide a combination timer and electric magnetic control in which power from the timer motor is used for equalizing the pull-in and drop-out characteristics of the electromagnet.

Other objects will appear from the following description and appended claims.

For a full disclosure of the invention reference is made to the following detailed description and to the accompanying drawings in which:

FIG. 1 is a front elevation of the new control device with a portion of the case removed to shown the working mechanism.

FIG. 2 is a side view of FIG. 1.

FIG. 3 is an enlarged view of the cam shaft assembly.

FIGS. 4, 5 and 6 show the switch and cam follower locations assumed during different portions of the operating cycle. 1

FIG. 7 is a schematic Wiring diagram of a typical installation.

Referring to FIGS. 1 and 2, the mechanism is mounted in a housing including a back plate 1 and a front plate 2 which supports a switch panel 3. This switch panel supports a switching mechanism consisting of flexible switch blades 4, 5 and 6 carryingcontacts 7, 8 and 9 respectively. The switch also includes astationary contact bracket 10 carrying a contact 11. The switch blades 4, 5 and 6 are of unequal lengths. Thus, blade 5 is slightly longer than blade 4, and blade 6 in turn is slightly longer than blade 5. All of the switch blades are biased downwardly as seen in FIG. 1.

The switch blades 4, 5 and 6 are operated by means of a pair ofcam followers 12 and 13 which are supported side by side on ashaft 14 which extends between the back and front plates 1 and 2. Thecam follower 12 is made of insulation material and is staked to a cam follower bearing 15 which is loosely carried onshaft 14. The cam follower 13 is also made of insulation material and is attached to abearing 16 also carried onshaft 14.

Bothcam followers 12 and 13 ride upon acam 18 which is carried on acam shaft 19 also extending between plates 1 and 2. Thiscam shaft 19 carries agear 20 which is driven by atimer motor 21 through suitable intermediate gearing. As shown in FIG. 3, thegear 20 is carried on ahub 22 which is pressed on shaft 3,135,908 Patented June 2, 1964 19. Also atension washer 23 is interposed between the gear and shaft so as to provide a friction clutch betweengear 20 andshaft 19. This permits theshaft 19 to be manually turned by a screw driver for testing out the system.

Also mounted on the plate 1 is asolenoid 25 of usual construction having a coil and aplunger 26. This solenoid plunger is pivotally attached to abell crank lever 27 carried by ashaft 28 which extends between plates 1 and 2. Atorsion spring 30 is carried by theshaft 28. One leg of this spring bears against the side of the case and the other leg of the spring bears on the pin 31 which attaches thebell crank 27 to the solenoid plunger. Thespring 30 thus serves to bias the solenoid plunger 26 downwardly, and to bias lever 27 in a counterclockwise direction.

Thecam follower 12 in addition to being controlled by thecam 18 is also actuated by thebell crank lever 27. This actuation is performed by apin 32 which is carried by thebell crank 27 and which extends into ahole 33 in thecam follower 12. Thebell crank 27 in addition to being actuated by thesolenoid plunger 26 is also actuated by acam 35 which is carried 'by thecam shaft 19. Thiscam 35 is loosely carried on theshaft 19 and is driven by apin 36 which is carried by thecam 18 which in turn is pressed over knurls onshaft 19. Atorsion spring 37 is carried by theshaft 19 and located betweencams 18 and 35. One end of this spring bears against thepin 36 and the other end is formed to fit behind thecam 35. This spring biases thecam 35 in a counter-clockwise direction relative to earn 18 as seen in FIG. 1.

Referring to FIG. 7, thecompressor 40 is controlled by a contactor or motor starter having acoil 41 and switches 42 and 43. This motor starter is controlled by athermostat 44 through contacts 7 and 11 of the switching mechanism.

Operation The parts in FIGS. 1 and 7 are shown in the standby. positions where the control unit is awaiting a call from cooling from the thermostat to start the compressor. At this time contacts 7 and 8 are engaged so that thethermostat 44 is in circuit with thetimer motor 21. C011- tacts 7 and 11 are open which prevents the thermostat from energizing thecontactor coil 41 or thetimer solenoid 25.

Referring in particular to FIG. 1, thecam follower 12 has dropped off thecam 18. However, cam follower 13 is slightly longer than thecam follower 12 and this cam follower 13 is still riding the top of thecam 18.

In this standby position, thecam 35 has been driven by thepin 36 and has lifted the horizontal portion of thebell crank 27 to a point where thesolenoid plunger 26 is almost at the upper limit of its range of movement. At this time thespring 37 has been compressed as its torque is insufficient to drive thecam 35 against the load imposed by the cam follower portion of thebell crank 27.

It will be noted thatcam follower 12 at this time is not engaged with any of the switch blades. However, the rear cam follower 13 which is still riding thecam 18 has portions which engage the switch blades 4 and 6. This has lifted the blade 4 to the point at which the contacts 7 and 8 are engaged. This follower 13 has also lifted the switch blade 6 so thatcontacts 8 and 9 are separated.

When the thermostat calls for cooling it energizes thetimer motor 21. This timer motor starts running and rotates thecam shaft 19 in a counter-clockwise direction as seen in FIG. 1. In approximately fifteen seconds the cam follower 13 drops off thecam 18 and the switch blades now energized position.

assume the positions shown in FIG. 4. The cam follower 13) in dropping offcam 18 rotated in a counter-clockwise direction. This released blade 4 thus allowing contacts 7 and 11 to close. During this dropping off movement of cam follower 1.3, the switch blade 5 followed switch blade 4 downwardly until it engaged thecam follower 12 which now holds blade 5 in an intermediate position in which the contacts 7 and 8 are separated. The switch blade 6 also moved downwardly with this counter-clockwise rotation of the cam follower 13. However, this motion was not suflicient to entirely close the gap betweencontacts 8 and 9 so that these contacts are still separated.

The parts are now in the run position. Opening of contacts '7 and 8 stopped the timer motor. Closing of contacts '7 and 11 energized thecontactor coil 41, thus starting the compressor 49. This also simultaneously energized thesolenoid 25 in the timer. This caused upward movement of thesolenoid plunger 26 to the upper limit of its stroke and thus caused the bell cranklever 27 to disengage thecam 35. This removed the holding force which prevented thespring 37 from rotating thecam 35. As a result thespring 36 now causes rotation of thecam 35 in a counter-clockwise direction, so that it clears the cam follower section of thebell crank 27.

The parts now remain in this position and the compressor operates until the thermostat becomes satisfied. When this happens, the thermostat opens its circuit and thus de-energizes both the timer solenoid and thecontactor coil 41. The compressor thus stops. Inasmuch as thecam 35 is no longer under the bell crank 27, de-energization of the solenoid coil permits the biasingspring 30 to rotate the bell crank 27 in a counter-clockwise direction as seen in FIG. 1. Thepin 32 in the bell crank now engages the right side of thehole 33 incam follower 12 and rotates thecam follower 12 in a clockwise direction as seen in FIG. 1. The parts now assume the positions shown in FIG. 5. It will be noted that thecam follower 12 has lifted the blade 4 so as to break contacts '7 and 11. It has also lifted the blade 5 to cause engageintent ofcontacts 8 and 9. Due to contacts 7 and 11 now being opened, the thermostat is disconnected from thecontactor coil 41. Thus thecoil 41 would remain de-energized even if the thermostat should immediately call for cooling. Inasmuch as thetimer solenoid 25 is also connected through timer contacts 7 and 11, the opening of these contacts prevents the thermostat from energizing the timer solenoid at this time.

The timer motor now runs, rotating the cam shaft in the counter-clockwise direction as seen in FIG. 1. During this motion thecam 35 remains stationary until after the lost motion between it and thepin 36 is taken up. During this movement thespring 37 is rewound for the next cycle. As the cams rotate, the bell crank 27 remains stationary until after thecam 18 has come under thecam follower 12. After this has taken place, the bell crank 27 is cammed in a clockwise direction and thus thepin 32 is shifted to the left so as to free the cam followerlZ for dropping off" itscam 18. During this same movement thecam 18 comes under the cam follower 13 and thus the parts have assumed the positions shown in FIG. 6.

After a suitable delay such as five minutes, thecam follower 12 drops olf thecam 18 and the parts reassume the standby position shown in FIG. 1.

From the foregoing description it will be noted that the load switch 711 can be closed only by the timer. This switch is opened instantly by thesolenoid 25 dropping out :in response to the thermostat becoming satisfied. Once the switch is opened in this manner the solenoid is rendered incapable of reclosing the switch and it can close again only after the timer has run through its delay cycle.

It will be noted that the earn 35 utilizes power from the timer motor to move the solenoid almost back to its t this time the cam and bell crank 27 act as a holding means for maintaining the solenoid plunger in this almost energized position. When the solenoid is energized thecam 35 moves out from underlever 27 due to the action ofspring 37. This, in effect, releases the holding means so that the solenoid is free to drop out when it is de-energized.

This arrangement, in which the solenoid is moved almost to its energized position by the timer motor decreases the amount of work which the solenoid must do. Thus a comparatively small solenoid can be used. Also, this arrangement brings the pull-in and drop-out voltages of the solenoid close together and permits the solenoid to also serve as a low voltageprotector.

From the foregoing it will be apparent that the invention interposes a positive delay between the time the compressor stops and the time that it can be restarted. It will also be seen that the invention interposes a delay between the time the thermostat calls for cooling and the time the compressor is started. This feature prevents false starts of the compressor due to vibration, etc., of the thermostat.

While the invention has been shown and described in connection with an air conditioning or refrigeration control system, it will be obvious that certain features of the invention are of broader scope and can be used in other applications.

While a preferred form of the invention has been shown and described it will be apparent that many changes can be made without departing from the spirit and scope of the invention. It is therefore desired to be limited only by the scope of the appended claims.

I claim:

1. In a control system for a condition changing system including a compressor, a condition responsive means for controlling said compressor, a switch interposed between said condition responsive means and said compressor, means including a timer motor and a solenoid mechanically and conjointly operating said switch, said solenoid being controlled by said condition responsive means and being arranged to open said switch when the condition responsive means stops the compressor, means actuated by said solenoid when opening said switch for starting said timer motor, and means actuated by said timer motor for reclosing said switch after said timer motor has run for a predetermined time.

2. In a control system for a condition changing system including a compressor, a condition responsive means for controlling said compressor, a switch interposed between said condition responsive means and said compressor, means including a timer motor and a solenoid for mechanically and conjointly operating said switch, said solenoid being controlled by said condition responsive means and being arranged to open said switch when the condition responsive means stops the compressor, means actuated by said solenoid when opening said switch for starting said timer motor independently of said condition responsive means, means for placing said timer motor under the control of the condition responsive means after a predetermined time, and means actuated by the timer motor after it has run for a predetermined time under the control of said condition responsive means for reclosing said switch.

3. In a control system for a condition changing system including a condition changer and a condition responsive device for controlling said condition changer, a control device interposed between said condition responsive device and condition changer, said control device including a solenoid, a time motor, and a switch mechanism having two outer contacts and two movable inner contacts, one outer contact being connected to the condition changer and the adjacent inner contact connected to the condition responsive device, the other inner contact being connected to the timer motor and the other outer contact being connected to a power service, and means operated conjointly by the timer motor and solenoid for actuating said two movable inner contacts.

4. In a control system for a condition changing system including a condition changer and a condition responsive device for controlling said condition changer, a control device having a switch interposed between said condition responsive device and said condition changer, said control device including an electro-magnet having a coil,

and a movable member arranged to move in a first direction When the coil is energized, said coil being controlled by the condition responsive device and said movable member being arranged to open said switch upon deenergization of said coil, a timer arranged to reclose said switch, means actuated by said movable member for starting said timer, means actuated by said timer for moving said movable member in said first direction, means for holding said movable member in a predetermined position, and means actuated by further movement of the movable member by energization of said coil for releasing said, holding means.

5. In an automatic control, a switch, a timer arranged to operate said switch in one direction, an electro-magnet having a coil and a movable member arranged to move in a first direction when the coil is energized, said movable member being arranged to operate said switch in the opposite direction when said movable member moves in a direction opposite to said first direction, said timer being arranged to move said movable member in said first direction independently ofsaid coil to a predetermined position, means for holding said movable memher in said predetermined position, and means actuated by further movement of said movable member by said coil for releasing said holding means.

6. In a timing control, an electric timer motor, a control deviceactuated by said timer motor, an electromagnet having a coil and a movable member arranged to move in a first direction when the coil is energized, means operated by the timer motor for moving said mov able member in said first direction, holding means for holding said movable member in a predetermined position, and means actuated upon further movement of said movable memberby energization of said coil for releasing said holding means.

7. In an automatic control, an electro-magnet having a coil and a movable member arranged to move in a first direction when said coil is energized, biasing means for biasing said movable member in the opposite direction, a control device actuated by said movable member, means independent of said coil for moving said movable'mernher in said first direction and for holding said movable member in a predetermined position, and means actuated upon further movement of said movable member by energization of said coil for releasing said holding means.

References Cited inthe file of this patent UNITED STATES PATENTS

Claims (1)

1. IN A CONTROL SYSTEM FOR A CONDITION CHANGING SYSTEM INCLUDING A COMPRESSOR, A CONDITION RESPONSIVE MEANS FOR CONTROLLING SAID COMPRESSOR, A SWITCH INTERPOSED BEBETWEEN SAID CONDITION RESPONSIVE MEANS AND SAID COMPRESSOR, MEANS INCLUDING A TIMER MOTOR AND A SOLENOID MECHANICALLY AND CONJOINTLY OPERATING SAID SWITCH, SAID SOLENOID BEING CONTROLLED BY SAID CONDITION RESPONSIVE MEANS AND BEING ARRANGED TO OPEN SAID SWITCH WHEN THE CONDITION RESPONSIVE MEANS STOPS THE COMPRESSOR, MEANS ACTUATED BY SAID SOLENOID WHEN OPENING SAID SWITCH FOR STARTING SAID TIMER MOTOR, AND MEANS ACTUATED BY SAID

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