DE102007052532B4 - Safety system for securing compressors in refrigeration systems - Google Patents

Abstract

Safety system to secure compressors in refrigeration systems with at least one condenser (7), evaporator (8) and compressor (6); a collector (10) and a dryer (11), the states of a number of switches and parameters being simultaneously recorded and evaluated under computer control in such a way that a high pressure limiter (1) switches off the compressor (6) immediately in the event of a malfunction and an automatic switch-back is not possible is; in the event of a fault in the motor temperature (3), the compressor (6) switches off immediately and automatic switch-back is not possible; A high-pressure switch (2) switches off the compressor (6) immediately in the event of a fault and automatic switching back several times is possible; a suction pressure switch (5) switches off the compressor (6) immediately in the event of a malfunction and automatic switching back several times is possible; in the event of an oil fault, the compressor (6) switches off after a time delay has elapsed and an automatic switch back is possible; in the event of a fault in the liquid level (9) in the collector (10) the compressor (6) switches off after a time delay and an automatic switch-back ...

Description

The invention relates to a system for the safety of compressors (hereinafter also referred to as refrigeration compressors) in refrigeration systems with at least one condenser, at least one evaporator, a collector and a dryer.

Refrigeration systems with a separate safety system for refrigeration compressors are not yet used. In the control of refrigeration systems often a simple protection / monitoring function is integrated, in which mostly only one parameter, the temperature or the pressure are monitored, for. As the temperature of the coolant before and after the evaporator. These solutions could not be used for other refrigeration systems.

In the DE 42 42 848 A1 For example, a refrigeration system and a method for controlling a refrigeration system are described. A control device includes a temperature and / or pressure sensor at the input and a temperature sensor at the outlet of the evaporator. These readings are required for overheating temperature control. A safety system that prevents switching on the refrigeration compressor in the presence of a fault or causes a shutdown, does not exist.

The font DE 30 40 496 A1 describes a heating system with a heat pump, which has, inter alia, a locking stage and a fault shutdown for a power supply to the drive unit of the heat pump controlling circuit breaker.

In Scripture EP 0 787 245 B1 a liquid level regulator is described, which is in particular provided for controlling the oil level in a compressor crankcase, wherein in a chamber containing the liquid, a float is provided, which controls a liquid valve.

The font DE 84 28 748 U1 discloses a monitoring and control device for refrigeration systems and heat pumps, in which the operating conditions of the components of the refrigeration system are displayed by visually easily assignable to the components control lamps.

From the DE 35 17 222 A1 An operating method and a control arrangement for a refrigeration system is known. A microcomputer control assembly determines, prior to start-up and intermittently during operation of the refrigeration system, whether a signal provided by a sensor is within normal limits. If a limit value of the sensor signal is exceeded, the refrigeration system can not be switched on or is switched off with a time delay during operation after an alarm signal. At least one fluid flow sensor is used as the sensor. This arrangement offers no security against other malfunctions of the refrigeration system and is not suitable for different refrigeration systems.

The invention is therefore based on the problem to propose a system for the safety of refrigeration compressors in refrigeration systems with a condenser, an evaporator, a collector and a dryer, the great security when switching on and operating different refrigeration systems by taking into account all acting on the function of the refrigeration compressor disturbances allows, requires little effort, has a high degree of IP protection and can be mounted in a small housing directly on the refrigeration compressor.

The problem is solved according to the invention by the features specified in claim 1. Further embodiments are contained in the subclaims.

The safety system computer-controlled recorded the conditions in the refrigeration system with at least one refrigeration compressor, while the safety high-pressure limiter, the high-pressure switch, the engine temperature through a PTC thermistor, the compressor oil, the liquid level in the collector and the suction pressure switch are detected and evaluated simultaneously. Each safety device of the refrigeration system has an influence on the function of the refrigeration compressor or the refrigeration compressor.

The safety high-pressure limiter switches off the compressor immediately in the event of a fault and an automatic downshift is not possible.

The high-pressure switch switches off the compressor immediately in the event of a fault and multiple automatic downshifts are possible.

A malfunction of the engine temperature shuts off the compressor immediately and an automatic downshift is not possible.

A compressor oil malfunction shuts off the compressor after a time delay has elapsed and an automatic downshift is possible.

If the liquid level in the collector is disturbed, the compressor switches off after a time delay and an automatic downshift is possible.

The suction pressure switch switches off the compressor immediately in the event of a fault and multiple automatic downshifts are possible.

An existing fault is displayed optically and / or acoustically.

The safety system is independent of the type and manufacturer of the compressor, evaporator, collector, dryer, condenser and safety devices. The safety system has very small dimensions and a very high degree of IP protection and can be mounted directly on the refrigeration compressor. Thus, no large cabinet is required. The safety of the plant and the environment are also increased. The invention allows great security when switching on and operating the different refrigeration systems by taking into account all acting on the function of the refrigeration compressor disturbances. In production, installation, operation and maintenance, a small effort is required.

The safety system according to the invention can be used in all refrigeration systems with at least one refrigeration compressor, d. H. also be used in heat pumps, drying plants, ice machines and dehumidifying with one or more compressors.

The invention will be explained in more detail using an exemplary embodiment. The accompanying drawing shows in

1 a system diagram with the security system according to the invention.

In 1 is a refrigeration system in a known series arrangement of refrigeration compressor 6 , Liquefier 7 , Collector 10 , Dryer 11 and evaporator 8th shown. The safety devices Safety high pressure limiter 1 , High pressure switch 2 , Temperature sensor for the engine temperature by means of PTC thermistor 3 , Sensor for compressor oil 4 , Suction pressure switch 5 and fluid level sensor 9 are simultaneously detected and evaluated by means of a microcomputer. The safety high pressure limiter 1 , the high pressure switch 2 and the suction pressure switch 5 are pressure switches, which are marked with P and have an opener, which opens in the event of a fault. The sensors for compressor oil 4 and for the fluid level 9 are level and level displays with normally closed contact. The measurement of the engine temperature 3 takes place as a measurement of resistance values with a PTC.

The safety high pressure limiter 1 switches the compressor 6 immediately. An automatic downshift is not possible. The associated LED lights up and an acoustic detector sounds in continuous tone.

The high pressure switch 2 switches the compressor 6 immediately. A repeated automatic downshift is possible. The number is limited between 3 × and 8 ×. The associated LED lights up in the event of a fault after all reclosing options have elapsed and flashes after reclosing. In the event of a fault, an acoustic detector sounds in continuous tone.

The suction pressure switch 5 switches the compressor 6 immediately. A repeated automatic downshift is possible. The number is limited between 3 × and 8 ×. The associated LED lights up in the event of a fault after all reclosing options have elapsed and flashes after reclosing. In the event of a fault, an acoustic detector sounds in continuous tone.

The liquid level in the event of a fault in the collector 9 switches the compressor 6 not immediately, but only after expiration of a time delay. An automatic downshift is possible. The associated LED lights up in the event of a fault after a time delay of 15 minutes to 1 h. In the event of a fault, an acoustic detector sounds in continuous tone. The associated LED flashes in the time delay.

An oil disorder 4 switches the compressor 6 not immediately, but only after a time delay from. An automatic downshift is possible. The associated LED lights up in the event of a fault after a time delay of 60 s-300 s and flashes in the time delay. In the event of a fault, an acoustic detector sounds in continuous tone. In the event of a fault, the sensor switches the motor temperature (PTC thermistor 3 ) the compressor 6 immediately. An automatic downshift is not possible. The associated LED lights up in the event of a fault. In the event of a fault, an acoustic detector sounds in continuous tone.

A reset of the safety devices 1 ; 2 ; 3 ; 4 ; 5 and 9 is only possible by pressing a reset button.

The safety system has relays to start the compressor 6 via a manual-O-automatic switch and for the transmission of fault messages. If the manual O-automatic switch is set to "manual", the external enable is bypassed. The operation of the refrigeration compressor is indicated by an LED. The refrigeration compressor switches on after a startup delay. The LEDs used can be checked with a button. This button also acknowledges the fault messages.

The equipment of refrigeration systems with safety and control devices depends on the required function of the system and the size of the machines. Small systems can also be operated without safety high pressure limiter, oil monitoring and engine temperature monitoring. In this case, these inputs are provided with a bridge and thus have no influence on the result. The transfer of signals from control devices and the forwarding to the power unit are realized in the safety system according to the invention with potential-free contacts. But it is possible to transfer these signals over a network.

LIST OF REFERENCE NUMBERS

1

safety high

2

High pressure switch

3

Engine temperature / PTC

4

compressor oil

5

Saugdruckschalter

6

refrigeration compressors

7

condenser

8th

Evaporator

9

liquid Level

10

collector

11

dryer

Claims (6)

Safety system for securing compressors in refrigeration systems with at least one condenser ( 7 ), Evaporator ( 8th ) and compressors ( 6 ); a collector ( 10 ) and a dryer ( 11 ), wherein computer-controlled simultaneously the states of a number of switches and parameters are detected and evaluated such that a safety high-pressure limiter ( 1 ) in case of fault the compressor ( 6 ) switches off immediately and an automatic downshift is not possible; in the event of a fault in the engine temperature ( 3 ) of the compressor ( 6 ) switches off immediately and an automatic downshift is not possible; a high pressure switch ( 2 ) in case of fault the compressor ( 6 ) switches off immediately and a repeated automatic downshift is possible; a suction pressure switch ( 5 ) in case of fault the compressor ( 6 ) switches off immediately and a repeated automatic downshift is possible; at an oil fault of the compressor ( 6 ) switches off after a time delay and an automatic downshift is possible; in case of a malfunction of the liquid level ( 9 ) in the collector ( 10 ) of the compressor ( 6 ) switches off after a time delay and an automatic downshift is possible; and an existing fault is displayed visually and / or acoustically, wherein the safety system in a housing directly on the refrigeration compressor ( 6 ) is mounted. Safety system according to claim 1, characterized in that further safety-relevant parameters and measures from the group of: oil temperature too high, oleic acid level too high, oil flow disturbance, hot gas temperature too high, refrigerant quantity in the collector ( 10 ) too low, compressor head temperature too high, suction gas temperature at the compressor ( 6 ) too high, phase sequence control and phase failure protection, motor current monitoring and external messages from soft starters and the function of the frequency inverter are recorded and evaluated. Safety system according to one of the preceding claims, characterized in that the transfer of signals from control devices and the forwarding to the power unit is realized with floating contacts. Safety system according to one of claims 1 to 3, characterized in that for an optical display luminous and / or flashing LED or LCD are used for display in plain text. Safety system according to one of claims 1 to 4, characterized in that the displays compressor oil ( 4 ) and / or liquid level ( 9 ) Are level and level displays with normally closed contact. Safety system according to one of claims 1 to 5, characterized in that the measurement of the engine temperature ( 3 ) by measuring resistance values using PTC thermistors.

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