DE1172759B - Pressure-dependent switching mechanism for electrical systems - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Boarding school Class: H 02 c

German class: 21 c - 40/04

Number: 1 172 759

File number: R 20795 VIII d / 21 c

Filing date; March 16, 1957

Opening day: June 25, 1964

The invention relates to a switching mechanism for electrical systems with an between two control positions working switch and one responsive to an operating state of the system pressure-sensitive organ, which when responding to changes in the operating state in a Direction over a given range is movable to the switch from its one control position in the other to fold, and which controls a blocking device that when the Pressure in the system is moved beyond a predetermined limit in one direction, to flip the switch in its other control position, and which also acts to the effect when Responsive to changes below the predetermined limit the movement of the pressure sensitive Prevent organ in the opposite direction within the given range of motion, wherein the blocking device has a pivotably mounted part which, when responding of the pressure-sensitive organ to an increase in pressure from the organ against the force a spring operatively connected to the pivotable member is movable in one direction.

Switching mechanisms of this type are z. B. known several times in refrigeration or freezing technology, however, in these the pressure-sensitive organ and the parts operated by it all follow changes in pressure evoked movements. These movements increase the wear and tear and have frequent a change in the setting resulting in inaccurate operation or failure of the switching mechanism can lead.

In contrast, the purpose of the invention is to provide a switching mechanism of the aforementioned Art to create in which the pressure-sensitive organ and the parts operated by it the movements caused by pressure changes in the system to be controlled only in one direction follow and only if the previous maximum value of the pressure is exceeded.

According to the invention, this purpose is achieved in that the pivotable part is wedge-shaped Carries cam which is held during the movement of the part in engagement with a follower part, so that between them a wedge effect is created, which after a movement of the pivotable part in which prevents one direction from moving in the opposite direction.

In one embodiment of the invention, the cam follower part is in engagement with the cam surface and is guided in such a way that when the pressure-dependent switching mechanism moves
electrical systems

Applicant:

Ranco Incorporated, Columbus, Ohio (V. St. A.)

Representative:

Dr. E. Wiegand, Munich 15, and

Dipl.-Ing. W. Niemann,

Hamburg 1, Ballindamm 26, patent attorneys

Named as inventor:
Frederick Arthur Greenawalt,
Columbus, Ohio (V. St. A.)

Claimed priority:

V. St. v. America March 21, 1956 (572 935)

pivotable part can move in one direction transverse to the direction of movement of the cam, to follow the cam surface and create a stop that prevents the movement of the part in the opposite direction blocked, and that means are provided during the movement of the pivotable part in one direction hold the trailing part in engagement with the cam surface.

The invention can e.g. B. advantageous in a control device for one of an electric motor Powered freezer can be used to open the motor circuit, if the system is on excessively high pressure is built up.

In the drawing, an embodiment of the invention is shown, for example.

Fig. 1 shows a switching mechanism in section, which in a schematically shown freezer is switched and serves to shut down the system in the event of an excessively high pressure of the coolant;

F i g. 2 and 3 are sectional views of the switching mechanism showing certain parts in different Positions are shown;

F i g. 4 is a fragmentary view showing certain parts of the switching mechanism on a larger scale reproduces.

In the preferred embodiment of the invention is a usually closed electrical one Switch 5 is provided, which by a bellows 6, which the pressure of the coolant in the high-

409 627/342

pressure side of the freezer to be controlled is subject, can be opened when the pressure reached a predetermined maximum. The movement of the bellows is controlled by a lever 7 on the switch transmitted, and an adjustable spring 8 counteracts the expansion of the bellows to apply the pressure regulate at which the switch is opened; this design is generally known.

The lever can move freely according to the expansion of the bellows, but its movement is at a pressure reduction in the bellows due to the cooperation between a cam 9 on the Lever 7 and a stop screw 10 blocked, carried by a sliding rod 11 pushed upwards which is prevented from upward movement by the screw resting against the cam surface is being held. When the lever 7 moves towards the switch open position (counterclockwise when looking at the drawing), the slide rod 11 moves accordingly the required way up to get the screw in contact with the cam hold so that the screw blocks any clockwise movement of the lever. One more ins a detailed explanation of the embodiment of the invention follows.

The switching mechanism comprises a suitable housing 12 in which the switch 5 is included. The switch 5 is a conventional snap-action switch and is made from a base 13 borne dielectric material, which is inserted into an opening in a wall of the housing is. In the illustrated embodiment, the switch has a contact leaf spring 14 which is attached to a End is connected to a connector 15, and its opposite end, which a contact 16 carries, moves between an electrically isolated stop 17 and a contact 18, which is attached to a second connection piece 19 which is embedded in the base 13.

The free part of the contact spring 14 is moved from one position to the other by a snap action moved by a tilting member 20, one end of which is pivotably mounted on the spring and the opposite end End is movable between limit positions by spaced apart Tongues are set which move between a fixed attachment as shown. That Tilting member 20 is pressed in the longitudinal direction against its pivot point by a tension spring 21, one end of which is pivotably connected to the tilting member and the other end to a drive lever 22 is attached, which is designed so that it pivots the spring and its force center line moved from one side to the other side of their dead center position relative to the tilting member, so that the lever can snap the tilting member between its limits and a snap movement of the contact spring 14 causes. The melting point for the drive lever 22 is relative to the stress line the spring 21 is arranged so that, when viewing the drawings, it is about its pivot point in a clockwise direction is therefore usually pressed into a position in which the contact 16 is on contact 18 closes.

The drive lever 22 is counterclockwise to open the switch by the Moved lever 7, which has the form of an angle lever, which consists of a metal stamping and is pivotable on a pin 26 which is mounted in the housing walls. The angle lever 7 is on one side with an electrical insulator 27 (Fig. 3), which electrically isolates the stamped piece from the switch drive lever 22. The lever 7 has opposing, spaced apart lugs 28 with continuous openings through which a pin 29 protrudes,

ίο which is screwed into the lower opening, like this can be seen from the drawing. The upper end of the pin is provided with a groove into which one end of the spring 8 engages and the opposite end of the spring is connected to a plate 31, which is screwed onto a screw 32 which is rotatably mounted in an opening in the housing 12 is. The tension of the spring 8 pulls the lever 7 clockwise, and by turning the Screw 32 for moving the plate 31 along the screw can determine the length and, consequently, the tension the spring can be adjusted to load the bellows 6 and cause the switch at a predetermined pressure is opened, as will be explained in detail below.

The lever 7 is moved counterclockwise by the bellows 6, which is a conventional, represents a pressure responsive device comprising two flexible plate-shaped parts interlocking with each other are soldered to form a hollow expandable chamber 35 to which a tube 36 is connected is to bring the bellows with the interior of the freezer to be controlled in connection, as in F i g. 1 is shown. The bellows is housed in a shell-shaped part, which is connected to the housing wall connected is. A rod 37 is connected to the middle of the upper wall of the bellows and engages the lower end of the pin 29 so that the lever 7 counteracts when the bellows expands is moved clockwise in the direction of opening the switch.

The construction of the bellows is such that a pressure prevailing in it, which is less than the smallest normal pressure in the freezing system, keeps the rod 37 in engagement with the pin 29. For example, if the normal pressure range in the freezer is 7 to 17.5 kg / cm ² , e.g. B. a pressure of 5.25 kg / cm ^{2 expanded} the bellows, so that the rod 37 with the pin 29 of the lever 7 is in engagement at all times. If it is desired that the switch be e.g. B. opens at 21 kg / cm ² pressure, the tension of the spring 8 is adjusted so that it loads the bellows so that a pressure of 21 kg / cm ^{2 is} required to expand the bellows enough so that the lever 7 pivoted into a position in which the switch is opened. It can be seen that when the pressure in the bellows approaches the value of 21 kg / cm ² , the lever 7 is moved counterclockwise and that the tension of the spring 8 increases when this movement of the lever stretches the spring. ^{It can be seen that when changes in the pressure below 21 kg / cm 2} occur in the switching mechanism described so far, which in principle is similar to known designs, the bellows 6 which actuates the switch

Lever 7 and tension spring 8 move in accordance with the increases and decreases in the Pressure of the coolant would move in the system.

5 6

According to the invention, however, the lever 7 is enclosed in a suitable chamber to be cooled after its movement opposite to the clock E. The circuit for the clockwise direction, due to the expansion of the bellows to it, pressor A contains a power source that prevents the grain from moving clockwise, and this line L 1, a line to be operated by hand, takes place through the 5 inputs formed on the lever 7. and circuit breaker 55, a line 56 to a cam 9 and the cam follower screw 10, side of the compressor motor, one of the other which is screwed through an opening in a flange 42 on the side of the motor to the connector 15 of the, which is on the sliding or reset rod switching mechanism leading line 57, which is Kon-11 formed. The slide rod 11 is a sheet metal clock spring 14, the contacts 16, 18 to the connecting piece punched piece, which in the lower end has a slot 45 extending in io 19 and a line 58 to the one longitudinal direction of the connection, by clamping a thermostatically operated switch F , to a head provided with guide pins 46 whose other terminal is connected to the to Stromer Stretches which source on a side wall of the overall live line L2.
housing is firmly attached. The upper part of the rod. The thermostatic switch F can be of any 11 will be in a slot with partially open side 15 of appropriate design, of which are guided in, which in an inwardly bent type of art numerous are known. It contains set 47 of the housing is designed. It can be seen a switch, which borrowed by a gas-filled bellows, that the rod 11 is actuated in the vertical direction, which has a sensor Fl, which can not move laterally, so that the temperatures in the cooling chamber E responds Screw 10 the movement of the lever 7 in the clock 20 and which is designed so that it blocks the switch clockwise when it closes with the cam 9 in when the temperature is a predetermined engagement. Altitude, and the switch opens when the

A tension spring 50, one end of which with the temperature at a predetermined minimum value

Housing connected and the other end of which has been reduced into one. It is known in the art that

Opening in a neck of the rod 11 is hooked, 25 the pressure of the refrigerant in the evaporator of the

pulls the rod 11 when looking at the drawing corresponds to the temperature of the evaporator, which

upwards, so that when the lever 7 measured against the working of the thermostatic switch F

Moving clockwise, the cam surface periodically rises and falls. Typical pressures are

Has endeavored to leave the screw 10, whereby within a range of 10.5 to 14 kg / cm ² ,

the rod is released so that it extends upwards 3 ° The tube 36 of the bellows 6 is connected to the outlet pipe

moved and connected to the touch between the screw of the freezer as shown, so

and the cam and thereby one that the pressure within the bellows is the same

Movement of the lever in a clockwise direction on one as in the high pressure side of the system,

subsequent reduction in pressure in the It can be seen that during normal

Bellows prevented. It can be seen that the cam 9 35 operating the freezer is the thermostatic

and the follow-up screw 10, similar to a longitudinal switch F, controls the operation of the motor of the system

the wedge attached to the lever 7 work when the temperature in the cooling chamber E regulates,

Lever moves counterclockwise and the pressure of the coolant in the high pressure

To see the movement of the lever clockwise the plant rises and falls between normal

to block. The bevel of the cam surface is 40 values. During the increase in pressure on one

such that the initial maximum value on the lever 7 in the clockwise direction, which is sufficient to

acting force is not able to the rod 11 at the lever 7 against the load of the spring 8 to

Drifting contemplation of the drawing down. move, the bellows 6 moves the lever 7 against the

The part 9 a of the cam 9 is, as best from the switch open position, and when the

F i g. 4 can be seen, relative to the direction of movement of the 45 pressure prevents the contact with the cam 9

Stangell beveled, and the part 9 a lies in the twisting screw 10 a return movement

essentially parallel to this direction of movement, so the lever due to the above-described wedge

that when the lever 7 moves counterclockwise. As stated above, the pressure is what

Sinn moved enough to open the switch - it is necessary to stretch the bellows against the

NEN, the screw 10 leaves the surface 9 a and to hold the 5 ° lever 7, considerably smaller than the smallest

allowed by the spring 50, the rod 11 up to the normal pressure, and therefore the bellows remains in the

determined by the slot 45 and the pin 46 position of the maximum normal pressure. As a result-

There is no movement of the bellows 6, the upward or outward limit (FIG. 3)

because. Lever 7 and the spring 8 during normal

By pushing the rod 11 inward, the 55 fluctuations in the pressures, with the exception of the screw 10, are moved to a position opposite the lower initial movement of the parts according to the highest end part of the cam surface 9 a , so that the head pressure that occurs without the pressure to He lever 7 by the tension of the switching range, which is necessary to open the switch to be determined spring 8 in the switch closed position, and therefore wear and tear (Fig. 1) can be returned. 60 fatigue of the bellows as well as the

The switching mechanism is installed in a freeze-tuning spring and the pivot pin (Fig. 1) used in which one shunned one.

Electric motor driven compressor A at its. Although the described preferred embodiment

Output side connected to a capacitor B approximate form of the invention works to the switch

which in turn can be opened by an appropriate 65 corresponding to a maximum pressure,

Expansion regulator D with an evaporator C in ver, the same principle can also be used to

binding stands, which with the compressor inlet in the switch corresponding to a minimum pressure

connected in the usual way. The evaporator C must be opened if this should be desired. mini-

I 172

Malpressure or low pressure disconnectors are known in the art. In any case the normal fluctuations in pressure do not cause any movement of the parts of the switching mechanism.

Claims (2)

Patent claims: 1. Pressure-dependent switching mechanism for electrical systems with one between two Control positions working switch and a responsive to an operating state of the system pressure-sensitive organ, which when responding to changes in the operating state is moveable in one direction over a given range to remove the switch from its to switch one control position to the other, and which controls a blocking device, when the pressure in the system rises above a predetermined limit in the one direction is moved to flip the switch in its other control position, and the also acts to respond to changes below the predetermined one Limit the movement of the pressure sensitive organ in the opposite direction within to prevent the given range of motion, the blocking device a has pivotably mounted part, which when the pressure-sensitive organ responds an increase in pressure from the organ against the force of one with the pivotable part operatively connected spring is movable in one direction, characterized in that that the pivotable part (7) carries a wedge-shaped cam (9) which, when moving of the part (7) is held in engagement with a trailing part (10) so that between them a wedge effect is caused, which after a movement of the pivotable part (7) in which prevents one direction from moving in the opposite direction. 2. Switching mechanism according to claim 1, characterized in that the cam follower part (10) is in engagement with the cam surface and is guided so that it is when the pivotable part (7) in one direction transversely to the direction of movement of the cam (9) can move to follow the cam surface and create a stop, which blocks the movement of the part (7) in the opposite direction, and that means are provided are that during the movement of the pivotable part (7) in one direction keep the trailing part (10) in engagement with the cam surface. Considered publications:
German Patent Nos. 903 974, 809088;
U.S. Patent No. 1,688,866. 1 sheet of drawings 409 627842 6.64 © Bundesdruckerei Berlin