JPS5836579Y2 - Protection device for vehicle air conditioner - Google Patents

Description

[Detailed description of the invention] This invention relates to a protection device for air conditioners, especially in air conditioners used for both cooling and heating, which reliably prevents the liquid bank phenomenon of the compressor during heating in winter. This invention relates to a protection device for equipment.

The applicant has previously proposed an air conditioner for vehicles (
Utility Model Registration Application No. 002163 (1978).

In other words, this air conditioner as shown in Figure 1 A1,
In piping 5, which communicates and connects the compressor 1, the condenser 2 that condenses the heat transfer medium during cooling, the liquid tank 4, and the heat exchanger 3 that evaporates the heat transfer medium during cooling and has an expansion valve 7a, respectively, A switching means 6 for reversing the circulation direction of the heat transfer medium is provided, and an evaporator 10 is provided in parallel with the condenser 2 to evaporate the heat transfer medium during heating and has an expansion valve 7b. With that housing 21,
The engine cooling water circulating in the Ujifugu 21 heats the evaporator main body 16, which is located relatively close to the engine in the engine room, so that it can be used for both heating and cooling.

In addition, symbols 8a and 8b in Figure 1 A 9 are heat sensitive parts, and symbol 9a
, 9b is piping, code 11.12 is one-way valve, code 13
．． 14 is a branch point, and 15 is a bypass.

According to such an air conditioner, during cooling, as shown in FIG. enters.

At this time, the condenser 2 is sufficiently cooled by the cooling fan or the wind generated by the vehicle speed, and the high temperature and high pressure heat transfer medium is condensed, passes through the liquid tank 4, is vaporized by the heat exchanger 3, and returns to the condenser 1.

During heating, as shown in the opening in Figure 1, the heat transfer medium exiting the compressor 1 is introduced into the heat exchanger 3 by the switching means 6, where it is radiated and condensed, and then passed through the liquid tank 4 and introduced into the evaporator main body 16. It vaporizes the engine cooling water circulating in the Ujifugu 21 surrounding the evaporator body 16 while absorbing the heat, and returns it to the compressor 1.

However, since the above-mentioned air conditioner functions as a heating device regardless of the engine cooling water temperature, for example, if the device is operated in a state where the engine cooling water circulating in the Ujifugu 21 of the evaporator 10 is cold immediately after the engine is started, the evaporator body There is a risk that a so-called liquid back phenomenon may occur in which the heat transfer medium circulating in the heat transfer medium 16 is sent to the compressor 1 without being sufficiently vaporized.

Such a liquid back phenomenon causes an overload on the compressor 1, and if the heat transfer medium returns to the compressor 1 in a liquid state, it may cause damage to the compressor 1 itself or the electromagnetic clutch, etc., and the heat exchange efficiency may decrease, resulting in so-called refrigeration. There was a problem that the cycle was no longer established.

The present invention was developed in view of this point of view, and includes a thermoswitch in the evaporator housing, which prevents the compressor from operating when the engine cooling water temperature is too low to completely vaporize the heat transfer medium. The present invention provides a protection device for an air conditioner as described above.

This invention will be described in detail below based on embodiments shown in the accompanying drawings.

FIG. 2 shows a cross-sectional view of the evaporator 10 used exclusively for heating.

This evaporator 10 consists of an evaporator body 16 having a large number of fins 17 on the outer periphery and a housing 21 that covers this evaporator body 16. This housing 21 has a water conduit pipe 24 for introducing heated engine cooling water.
and a water pipe 25 for sending this back to the engine body.
In addition, the water pipe 25 is provided with a control valve 22 for controlling the circulation of engine cooling water into the Ujifugu 21.
The control pulp 22 is opened and closed by a controller 23 that detects a change in temperature of the heat sensitive part 8b so that the temperature of the heat transfer medium reaches a predetermined temperature.

Further, this heat-sensitive portion 8b is connected and communicated with the expansion valve 7b through a pipe 9b.

Furthermore, a thermoswitch 46 is provided in the housing 21, and the thermoswitch 46 controls the temperature inside the housing 21.
The system detects the temperature of circulating engine coolant.

Further, the circuit diagram of the air conditioner protection device according to the above embodiment is shown in FIG. 3.

That is, in FIG. 3, an ignition key switch 31 is connected to a power source 30.

A cooler switch 32 and a template lever switch 33 are connected to the non-power side terminal of this ignition key switch 31.
, a heater switch 34 connected in series to this, a contact 36 of an electromagnetic relay 35 that closes by the excitation of a solenoid whose one end is connected to the non-power terminal of the heater switch 34 and the other end is connected to the ground circuit; A contact 39 of an electromagnetic relay 38 that is connected to a non-power side terminal and whose other end is closed by the excitation of a solenoid connected to a controller 3T that controls the operation of the compressor 1 during heating, and a fan switch 41 that operates a fan 40 are connected in parallel. Further, a defroster switch 42 is connected in parallel with the heater switch 34.

Then, connect the non-power side terminal of the cooler switch 32 to the non-power side terminal of the contact 39 of the electromagnetic relay 38,
One end is connected to the power supply side terminal of the fan 40, and the other end is connected to a contact 45 of a relay 44 that is closed by the excitation of a solenoid connected to a ground circuit via a vacuum switch 43 that is turned on after the engine is started.

In addition, a thermoswitch 46 connects the non-power side terminal of the contact 45 of the relay 44 to the ground circuit via a solenoid, and a power side terminal of the contact 48 of the relay 41, which is opened by the excitation of the solenoid via the thermoswitch 46, is connected respectively. connected in parallel.

The compressor 1 is also connected to the non-power supply side terminal of the terminal 48 of the relay 47.

Further, a switching means 6 for switching the circulation direction of the heat transfer medium is connected to the non-power supply side terminal of the contact 36 of the relay 35.

Also, in FIG. 3, an identification light 49 is connected to the power source 30 via the cooler switch 32 and the contact 39 of the electromagnetic relay 38.
, 50, there is a relay 24 which is always closed on the side of the blue identification light 49 that lights up during cooling to indicate that cooling is in progress, and is inverted to the side of red identification light 50 that lights up during heating to indicate that heating is in progress. A contact point 51 is provided.

The controller 37 has an engine speed of 1500 r.
switch 52 that detects that the vehicle speed is below 10 km/h and closes; switch 53 that detects that the engine coolant temperature is below 60°C and closes. switch 54 and a switch 5 that closes when it detects that the vehicle interior temperature is below 25°C.
5 and a switch 56 that closes when it detects that the air blowing temperature is 400C or less in heater mode are connected in parallel, and these switches 52, 53,
54, 55, and 56 are closed, the solenoid of the electromagnetic relay 38 is connected to the ground circuit.

Therefore, when the ignition key switch 31 is closed and the engine starts operating, the vacuum switch 43 is closed.

After that, when the driver moves the mode lever to the heater position and selects the heater mode, the heater switch 3
4 closes.

In this way, when the heater switch 34 is closed and the template lever is at the maximum heating position, the template lever switch 33
The closing relay 35 is activated to close the contact 36, and at the same time, the contact 51 is reversed from the blue identification light 49 side to the red identification light 50 side, and the switching means 6 is activated to operate as a heating device.

When fan switch 41 is closed in this state, fan 40 is activated, relay 44 is activated, and contact 45 is closed.

During this heating, when the temperature of the engine cooling water introduced into the evaporator 10 and the Ujifugu 21 is high, the thermo switch 46 becomes an open circuit and the switch 4 of the relay 47
8 closes.

Further, when the engine cooling water introduced into the housing 21 of the evaporator 10 is low, the respective contacts 52, 53, 54° 55 of the controller 37 are closed after the engine is started.
．． 56 satisfies predetermined conditions and becomes a closed circuit, the housing 2 near the outlet of the evaporator 10
Since the thermoswitch 46 attached to the compressor 1 detects the engine coolant temperature and is closed, the excitation of the solenoid via the thermoswitch 46 opens the terminal 48 of the relay switch 47 and the compressor 1 does not operate.

Here, the engine coolant temperature usually rises by 2 per minute.
0°C, for example, setting the temperature of the thermo switch to 2
When set to 00C, the compressor will not operate if the outside temperature is below 00C and the engine coolant is below 0°C, and the compressor will operate when the engine coolant temperature reaches 20C after about 1 minute due to engine operation. The air conditioner then begins to function fully as a space heater.

Therefore, according to the protection device for an air conditioner according to the present invention, when the device is used for interphase heating, the temperature of the engine cooling water introduced in the evaporator after engine startup is too low, so the heat transfer medium is not sufficient in the evaporator. If vaporization is not possible, this cooling water temperature can be detected by a thermoswitch and the start of the compressor can be controlled to prevent the occurrence of a liquid back phenomenon in which liquid that cannot be vaporized enters the compressor. When the temperature of the engine coolant introduced into the engine rises and reaches a predetermined temperature, the thermoswitch is automatically activated, opening the circuit and allowing the compressor to operate.As a result, overload due to the compressor liquid back phenomenon Since the compressor itself and the electromagnetic clutch are no longer affected, damage to the compressor itself, the electromagnetic clutch, etc., and a decrease in heat exchange efficiency can be completely prevented.

[Brief explanation of the drawing]

Figure 1A is a circuit diagram of the heat transfer medium during cooling of the air conditioner proposed earlier, Figure 1A is a circuit diagram of the heat transfer medium during heating of the air conditioner proposed earlier. FIG. 3 is an explanatory diagram of an evaporator in which heat is exchanged between engine cooling water and a heat transfer medium, and FIG. 3 is an electric circuit diagram of an air conditioner. 1...': 17 pL/sa, 2... Condenser, 3... Heat exchanger, 4... Liquid tank, 5... ...Piping, 6...
...Switching means, 7a...Expansion valve, 7b...
...Expansion valve, 10... Evaporator, 16...
...Evaporator body, 21...Using, 46...Thermo switch.

Claims (1)

[Scope of utility model registration request] It has a compressor 1, a condenser 2 that condenses a heat transfer medium during cooling, an evaporator 10 that heats with engine cooling water, a heat exchanger 3, and piping 5 that communicates between these, and sends out from the compressor 1. In an air conditioner that is used for both cooling and heating by switching the circulation path of the heat transfer medium by a switching means 6, the operation of the compressor 1 is controlled by a thermoswitch 46 that detects the temperature of cooling water flowing through the evaporator, A protection device for a vehicle air conditioner, characterized in that the compressor 1 does not operate when the cooling water temperature is below a predetermined temperature.