On-vehicle device controller and vehicle refrigeration cycle device

Abstract

To inhibit operation of a gasoline engine from becoming unstable when engine load control is terminated.SOLUTION: An on-vehicle device controller includes a control unit 40 which exercises engine load control for stopping on-vehicle devices 4, 21 which impose burdens on a gasoline engine 2 when a brake pedal whose operation force is reduced by a brake booster which utilizes a negative pressure of intake air of the gasoline engine 2 is depressed and the negative pressure is smaller than a predetermined value. The control unit 40 causes the on-vehicle devices 4, 21 to operate after an idle rotation number of the gasoline engine 2 is increased when the engine load control is terminated.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to an in-vehicle equipment control device that controls in-vehicle equipment mounted on a vehicle that runs on a gasoline engine, and a refrigeration cycle device used in a vehicle that runs on a gasoline engine. [Background technology]

[0002] Conventionally, brake boosters installed in vehicles powered by gasoline engines store the negative pressure generated in the intake system of the gasoline engine as brake negative pressure, and are driven by that brake negative pressure to reduce the force required to operate the brake pedal by the driver.

[0003] Here, the gasoline engine of a vehicle is subjected to not only the driving load but also the load of on-board devices such as the automatic transmission, compressor, alternator, etc. If these loads increase while the gasoline engine is idling, the idle speed control operates in the direction of opening the throttle valve to maintain the rotation speed of the gasoline engine, so that the intake negative pressure decreases and the brake negative pressure also decreases.

[0004] In particular, in vehicles such as refrigerated vehicles that have two refrigeration cycle devices, one for the passenger compartment air conditioning and the other for the luggage compartment air conditioning, the load on the gasoline engine is likely to be large because of the presence of two compressors, one for the passenger compartment air conditioning refrigeration cycle device and the other for the luggage compartment air conditioning refrigeration cycle device, which tends to reduce the intake negative pressure and the brake negative pressure.

[0005] In this regard, the vehicle equipment control device described in Patent Document 1 is configured to perform engine load control to stop vehicle equipment that applies a load to the gasoline engine when the brake pedal is depressed and the brake negative pressure is smaller than a predetermined value.

[0006] By stopping the on-board equipment, the load on the vehicle engine is reduced, so the amount of intake air for the gasoline engine is reduced and the throttle valve is controlled to the closed side, which increases the intake negative pressure and ensures the brake negative pressure required to drive the brake booster. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2023-71628 A Summary of the Invention [Problem to be solved by the invention]

[0008] However, in the above-mentioned conventional technology, when engine load control is terminated, i.e., when the on-board equipment is restarted, the load on the idling gasoline engine increases, causing the idle speed of the gasoline engine to drop and making the engine unstable.

[0009] SUMMARY OF THE PRESENT DISCLOSURE In view of the above, an object of the present invention is to prevent the operation of a gasoline engine from becoming unstable when engine load control is terminated. [Means for solving the problem]

[0010] In order to achieve the above object, the in-vehicle device control device according to claim 1 comprises: a control unit (40) that performs engine load control to stop an in-vehicle device (4, 21) that applies a load to the gasoline engine (2) when a brake pedal, the operation force of which is reduced by a brake booster that utilizes the negative pressure of the intake air of the gasoline engine (2), is depressed and the negative pressure is smaller than a predetermined value; When terminating the engine load control, the control unit (40) increases the idle speed of the gasoline engine (2) and then operates the in-vehicle devices (4, 21).

[0011] According to this, when the engine load control is terminated, the in-vehicle equipment (4, 21) is operated with the idle speed of the gasoline engine (2) increased, so that the idle speed of the gasoline engine (2) can be prevented from becoming lower than normal even if the load on the gasoline engine (2) becomes high when the in-vehicle equipment (4, 21) is operated. Therefore, it is possible to prevent the operation of the gasoline engine (2) from becoming unstable when the engine load control is terminated.

[0012] In order to achieve the above object, the vehicle refrigeration cycle device according to claim 2 comprises: a compressor (21) driven by a gasoline engine (2) for sucking, compressing, and discharging a refrigerant; a radiator (22) for radiating heat from a refrigerant discharged from the compressor (21); a pressure reducing section (23) for reducing the pressure of the refrigerant whose heat has been radiated by the radiator (22); an evaporator (123) for evaporating the refrigerant decompressed in the decompression section (23); a control unit (40) that performs engine load control to stop a compressor (21) when a brake pedal, the operation force of which is reduced by a brake booster that utilizes the negative pressure of the intake air of the gasoline engine (2), is depressed and the negative pressure is smaller than a predetermined value; When terminating the engine load control, the control section (40) increases the idle speed of the gasoline engine (2) and then operates the compressor (21).

[0013] According to this, since the compressor (21) is operated with the idle speed of the gasoline engine (2) increased, it is possible to prevent the idle speed of the gasoline engine (2) from becoming lower than normal even if the load of the gasoline engine (2) becomes high when the compressor (21) is operated, and therefore it is possible to prevent the operation of the gasoline engine (2) from becoming unstable when the engine load control is terminated.

[0014] The vehicle refrigeration cycle device according to claim 3 is the vehicle refrigeration cycle device according to claim 2, a pressure equalizing section (28) for equalizing pressure by communicating the suction side and the discharge side of the compressor (21); a pressure equalizing valve (26) for opening and closing the pressure equalizing section (28); When the compressor (21) stops, the control section (40) performs pressure equalization control to open the pressure equalization valve (26) so that the suction side and the discharge side of the compressor (21) communicate with each other.

[0015] According to this, the high pressure and the low pressure in the refrigeration cycle can be equalized while the compressor (21) is stopped, so that the compressor (21) can be smoothly restarted.

[0016] In addition, the reference symbols in parentheses for each means described in this column and in the claims indicate the correspondence with the specific means described in the embodiments described later. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a schematic diagram illustrating a transportation vehicle according to an embodiment. [Diagram 2] 2 is an overall configuration diagram of a luggage compartment air-conditioning and refrigeration cycle device used in the transport vehicle of FIG. 1. [Diagram 3] 3 is a block diagram showing an electronic control unit in the luggage compartment air-conditioning and refrigeration cycle device in FIG. 2. [Figure 4] 4 is a time chart illustrating a control process executed by the control device of FIG. 3. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] An embodiment will be described below. Fig. 1 is a cross-sectional view showing a transport vehicle 1 on which a vehicle refrigeration cycle device of the present embodiment is mounted. In Fig. 1, the arrows pointing up, down, front and rear indicate the up, down, front and rear directions of the transport vehicle 1.

[0019] The transport vehicle 1 of this embodiment has a cargo bed 11 at the rear side of a driver's cab 10 arranged at the front of the vehicle. The cargo bed 11 is formed in a box shape using a heat insulating material or the like. A cargo compartment 111 is formed within the cargo bed 11.

[0020] A gasoline engine 2 that uses gasoline as fuel, an automatic transmission 3 that is a speed change mechanism, and an alternator 4 that is a generator are mounted below the driver's cab 10. The gasoline engine 2 is an internal combustion engine that has a throttle valve that adjusts the amount of intake air. The vehicle is provided with a brake booster (not shown) that reduces the force required when the driver depresses the brake pedal (not shown).

[0021] The brake booster reduces the force required to depress the brake pedal by utilizing the negative pressure of the intake air of the gasoline engine 2. A negative pressure passage extending from the intake pipe of the gasoline engine 2 is connected to the brake booster. The negative pressure passage extends from a portion of the intake pipe of the gasoline engine 2 downstream of the throttle valve. An intake pressure sensor 47 that detects the intake pressure of the gasoline engine 2 is disposed in the negative pressure passage.

[0022] The negative pressure in the intake passage draws air from within the brake booster through the negative pressure passage, and the drawing of air creates a negative pressure in the brake booster, which drives the brake booster.

[0023] Although not shown, an opening for carrying in and out luggage and an opening / closing door for opening and closing the opening are provided on the side and rear of the loading platform 11. A loading compartment air conditioning unit 12 is arranged in the loading compartment 111.

[0024] 1, the luggage compartment air conditioning unit 12 draws in air from the luggage compartment 111, cools it, and blows it out into the luggage compartment 111. The temperature inside the luggage compartment 111 is adjusted by the air blown out from the luggage compartment air conditioning unit 12.

[0025] A first interior blower 122, a first evaporator 123, etc. are housed in a unit case 121 of the luggage compartment air conditioning unit 12. The first interior blower 122 is an electric blower driven by an electric motor.

[0026] By operating the first indoor blower 122, air in the luggage compartment 111 is sucked into the unit case 121 and cooled as it passes through the first evaporator 123, and the cool air that has passed through the first evaporator 123 is blown out from the unit case 121 into the luggage compartment 111. This cools the air in the luggage compartment 111, and the luggage in the luggage compartment 111 is refrigerated or frozen.

[0027] A cab air conditioning unit 13 is disposed in the cab 10. The cab air conditioning unit 13 draws in the air inside the cab 10 or outside air, cools or heats it, and blows it out into the cab 10. The temperature of the cab 10 is adjusted by the air blown out from the cab air conditioning unit 13.

[0028] A second exterior blower 132, a second evaporator 133, etc. are housed in a unit case 131 of the cab air conditioning unit 13. The second exterior blower 132 is an electric blower driven by an electric motor.

[0029] By operating the second exterior blower 132, the air in the operator's cab 10 or the outside air is sucked into the unit case 131 and passes through the second evaporator 133 to be cooled.

[0030] The unit case 131 also houses a heater core (not shown) and an air mix door (not shown). The heater core heats the air that has passed through the second evaporator 133 by exchanging heat with engine coolant. The air mix door adjusts the ratio of the airflow between the heater core and the air that bypasses the heater core, thereby adjusting the temperature of the air blown into the vehicle cabin.

[0031] The air that has passed through the second evaporator 133 and the heater core is blown out from the unit case 131 into the cab 10, as indicated by an arrow A3 in FIG.

[0032] Fig. 2 is an overall configuration diagram of the luggage compartment air-conditioning refrigeration cycle device 20 mounted on the transport vehicle 1 of Fig. 1. The luggage compartment air-conditioning refrigeration cycle device 20 includes a first compressor 21, a first condenser 22, a first expansion valve 23, a first evaporator 123, a first bypass valve 25, and a first equalizing valve 26.

[0033] The first compressor 21 compresses the sucked refrigerant and discharges it. For example, the first compressor 21 is disposed in an engine room of the vehicle.

[0034] For example, the first compressor 21 is an engine-driven compressor that is rotationally driven by the gasoline engine 2 via a first magnetic clutch (not shown). The first magnetic clutch is a driving force interrupter that interrupts the driving force transmitted from the gasoline engine 2 to the first compressor 21.

[0035] The cargo compartment air-conditioning refrigeration cycle device 20 uses an HFC refrigerant (specifically, R134a) as a refrigerant, and configures a subcritical refrigeration cycle in which the high-pressure side refrigerant pressure does not exceed the critical pressure of the refrigerant. The refrigerant is mixed with refrigeration oil for lubricating the first compressor 21. A portion of the refrigeration oil circulates through the refrigerant circuit of the refrigeration cycle device together with the refrigerant.

[0036] A first condenser 22 is connected to the discharge side of the first compressor 21. The first condenser 22 cools and condenses the high-pressure refrigerant by exchanging heat between the high-pressure refrigerant (gas refrigerant) discharged from the first compressor 21 and outside air (air outside the vehicle cabin) blown by a first exterior blower (not shown). The first condenser 22 is a radiator that dissipates heat from the refrigerant. The first exterior blower is an electric blower driven by an electric motor.

[0037] A first expansion valve 23 is connected to the outlet side of the first condenser 22. The first expansion valve 23 is a first pressure reducing section that reduces the pressure of the high pressure refrigerant (liquid refrigerant) condensed in the first condenser 22.

[0038] For example, the first expansion valve 23 is a temperature type expansion valve, has a temperature sensor that detects the degree of superheat of the refrigerant on the outlet side of the first evaporator 123 based on the temperature and pressure of the refrigerant on the outlet side of the first evaporator 123, and adjusts the throttle passage area by a mechanical mechanism so that the degree of superheat of the refrigerant on the outlet side of the first evaporator 123 falls within a predetermined range. The first expansion valve 23 may be an electric expansion valve that adjusts the throttle passage area by an electric mechanism.

[0039] The first evaporator 123 is connected to the outlet side of the first expansion valve 23. A low-pressure refrigerant (liquid refrigerant) decompressed by the first expansion valve 23 flows into the first evaporator 123, and this low-pressure refrigerant absorbs heat from the air blown by the first indoor blower 122 and evaporates, thereby cooling the air. The low-pressure refrigerant (gas refrigerant) evaporated in the first evaporator 123 is sucked into the first compressor 21.

[0040] A first bypass flow path 27 is connected to the discharge side of the first compressor 21 and the inlet side of the first evaporator 123. The first bypass flow path 27 is a bypass section through which the high-temperature refrigerant (hot gas) discharged from the first compressor 21 flows, bypassing the first condenser 22 and the first expansion valve 23. A first bypass valve 25 is disposed in the first bypass flow path 27. The first bypass valve 25 is a bypass opening / closing section that opens and closes the first bypass flow path 27.

[0041] A first pressure equalizing flow passage 28 is connected between the suction side of the first compressor 21 and the discharge side of the first compressor 21. The first pressure equalizing flow passage 28 is a pressure equalizing section that connects the suction side of the first compressor 21 and the discharge side of the first compressor 21 to achieve pressure equalization. A first pressure equalizing valve 26 is disposed in the first pressure equalizing flow passage 28. The first pressure equalizing valve 26 is a pressure equalizing flow passage opening / closing section that opens and closes the first pressure equalizing flow passage 28.

[0042] The first bypass valve 25 and the first pressure equalizing valve 26 are solenoid valves whose operations are controlled by a control signal output from the air conditioning control device 40.

[0043] 1 is similar to the configuration of the luggage compartment air-conditioning refrigeration cycle device 20. Therefore, in parentheses in FIG 2, a reference symbol corresponding to the cab air-conditioning refrigeration cycle device 30 is shown, and the cab air-conditioning refrigeration cycle device 30 is omitted from the illustration.

[0044] The cab air conditioning refrigeration cycle device 30 includes a second compressor 31, a second condenser 32, a second expansion valve 33, a second evaporator 133, a second bypass valve 35, and a second equalizing valve .

[0045] The second compressor 31 compresses the sucked refrigerant and discharges it. For example, the second compressor 31 is disposed in an engine room of the vehicle.

[0046] For example, the second compressor 31 is an engine-driven compressor that is rotationally driven by a vehicle engine (not shown) via a second magnetic clutch (not shown). The second magnetic clutch is a driving force interrupter that interrupts the driving force transmitted from the gasoline engine 2 to the second compressor 31.

[0047] The cab air-conditioning refrigeration cycle device 30 uses an HFC refrigerant (specifically, R134a) as a refrigerant, and configures a subcritical refrigeration cycle in which the high-pressure side refrigerant pressure does not exceed the critical pressure of the refrigerant. The refrigerant is mixed with refrigeration oil for lubricating the second compressor 31. A portion of the refrigeration oil circulates through the refrigerant circuit of the refrigeration cycle device together with the refrigerant.

[0048] A second condenser 32 is connected to the discharge side of the second compressor 31. The second condenser 32 cools and condenses the high-pressure refrigerant by exchanging heat between the high-pressure refrigerant (gas refrigerant) discharged from the second compressor 31 and outside air (air outside the vehicle cabin) blown by a second exterior blower (not shown). The second condenser 32 is a radiator that radiates heat from the refrigerant. The second exterior blower is an electric blower driven by an electric motor.

[0049] A second expansion valve 33 is connected to the outlet side of the second condenser 32. The second expansion valve 33 is a second pressure reducing section that reduces the pressure of the high pressure refrigerant (liquid refrigerant) condensed in the second condenser 32.

[0050] For example, the second expansion valve 33 is a temperature type expansion valve, has a temperature sensor that detects the degree of superheat of the refrigerant on the outlet side of the second evaporator 133 based on the temperature and pressure of the refrigerant on the outlet side of the second evaporator 133, and adjusts the throttle passage area by a mechanical mechanism so that the degree of superheat of the refrigerant on the outlet side of the second evaporator 133 falls within a predetermined range. The second expansion valve 33 may be an electric expansion valve that adjusts the throttle passage area by an electric mechanism.

[0051] A second evaporator 133 is connected to the outlet side of the second expansion valve 33. A low-pressure refrigerant (liquid refrigerant) decompressed by the second expansion valve 33 flows into the second evaporator 133, and this low-pressure refrigerant absorbs heat from the air blown by the second exterior blower 132 and evaporates, thereby cooling the air. The low-pressure refrigerant (gas refrigerant) evaporated in the second evaporator 133 is sucked into the second compressor 31.

[0052] A second bypass flow path 37 is connected between the discharge side of the second compressor 31 and the inlet side of the second evaporator 133. The second bypass flow path 37 is a bypass section through which the high-temperature refrigerant (hot gas) discharged from the second compressor 31 flows, bypassing the second condenser 32 and the second expansion valve 33. A second bypass valve 35 is disposed in the second bypass flow path 37. The second bypass valve 35 is a bypass opening / closing section that opens and closes the second bypass flow path 37.

[0053] A second pressure equalizing flow passage 38 is connected to the suction side of the second compressor 31 and the discharge side of the second compressor 31. The second pressure equalizing flow passage 38 is a pressure equalizing section that connects the suction side of the second compressor 31 and the discharge side of the second compressor 31 to achieve pressure equalization. A second pressure equalizing valve 36 is disposed in the second pressure equalizing flow passage 38. The second pressure equalizing valve 36 is a pressure equalizing flow passage opening / closing section that opens and closes the second pressure equalizing flow passage 38.

[0054] The second bypass valve 35 and the second equalizing valve 36 are solenoid valves whose operations are controlled by a control signal output from the air conditioning control device 40.

[0055] The air conditioning control device 40 is configured with a well-known microcomputer including a CPU, ROM, RAM, etc., and its peripheral circuits, and performs various calculations and processing based on control programs stored in the ROM.

[0056] The air conditioning control device 40 is a control unit that controls the operation of the first indoor blower 122, the first outdoor blower, the first compressor 21, the first bypass valve 25, the first pressure equalizing valve 26, the second outdoor blower 132, the second outdoor blower, the second compressor 31, the second bypass valve 35, the second pressure equalizing valve 36, etc. that are connected to the output side. The air conditioning control device 40 constitutes an in-vehicle equipment control device that controls in-vehicle equipment such as the first compressor 21 and the second compressor 31.

[0057] 3, various control sensors and various control switches are connected to the input side of the air conditioning control device 40. The various control sensors include a luggage compartment temperature sensor 41, a vehicle compartment temperature sensor 42, an outside air temperature sensor 43, a solar radiation sensor 44, a first evaporator temperature sensor 45, a second evaporator temperature sensor 46, an intake pressure sensor 47, etc. The various control switches include a brake switch 48, etc.

[0058] The luggage compartment temperature sensor 41 detects the temperature inside the luggage compartment 111. The vehicle interior temperature sensor 42 detects the temperature inside the vehicle interior. The outside air temperature sensor 43 detects the outside air temperature. The solar radiation sensor 44 detects the amount of solar radiation inside the vehicle interior.

[0059] The first evaporator temperature sensor 45 is an evaporator temperature detection unit that detects the refrigerant evaporation temperature (first evaporator temperature) in the first evaporator 123. The first evaporator temperature sensor 45 detects the heat exchange fin temperature of the first evaporator 123 and the temperature of the refrigerant on the outlet side of the first evaporator 123.

[0060] The second evaporator temperature sensor 46 is an evaporator temperature detection unit that detects the refrigerant evaporation temperature (second evaporator temperature) in the second evaporator 133. The second evaporator temperature sensor 46 detects the heat exchange fin temperature of the second evaporator 133 and the temperature of the refrigerant on the outlet side of the second evaporator 133.

[0061] The intake pressure sensor 47 is an intake pressure detection unit that detects the intake pressure of the gasoline engine 2. The brake switch 48 is a brake depression detection unit that detects depression of the brake pedal by the driver.

[0062] Various operation signals are input to the air conditioning control device 40 from an operation panel 50. The operation panel 50 is disposed near the instrument panel inside the vehicle cabin. The operation panel 50 is provided with a luggage compartment air conditioning operation switch for switching between operation and stop of the luggage compartment air conditioning refrigeration cycle device 20 (specifically, operation and stop of the first compressor 21), a cab air conditioning operation switch for switching between operation and stop of the cab air conditioning refrigeration cycle device 30 (specifically, operation and stop of the second compressor 31), a luggage compartment target temperature setting switch for setting a target temperature in the luggage compartment 111, a cab target temperature setting switch for setting a target temperature in the cab 10, and the like.

[0063] Furthermore, an engine control device 60 is connected to the output side of the air conditioning control device 40. The engine control device 60 is configured with a well-known microcomputer including a CPU, ROM, RAM, etc., and its peripheral circuits, and performs various calculations and processing based on a control program stored in the ROM.

[0064] A request signal related to the operation of the gasoline engine 2 is input to the engine control device 60 from the air conditioning control device 40. The engine control device 60 is a control unit that controls the operation of the gasoline engine 2 based on the request signal input from the air conditioning control device 40, the amount of operation of the accelerator pedal, etc. When the gasoline engine 2 is in an idling state, the engine control device 60 controls the rotation speed of the gasoline engine 2 to a predetermined idle rotation speed.

[0065] Specifically, when the gasoline engine 2 is idling and the first compressor 21 and the second compressor 31 are stopped, the engine control device 60 controls the rotation speed of the gasoline engine 2 to a normal idle rotation speed, and when the gasoline engine 2 is idling and at least one of the first compressor 21 and the second compressor 31 is operating (i.e., when the load on the gasoline engine 2 in the idling state becomes high), the engine control device 60 controls the rotation speed of the gasoline engine 2 to a speed higher than the normal idle rotation speed.

[0066] Next, the operation of the above configuration will be described. When the cargo compartment air-conditioning operation switch on the operation panel 50 is turned on, the first compressor 21 operates to operate the cargo compartment air-conditioning refrigeration cycle device 20. During normal operation of the cargo compartment air-conditioning refrigeration cycle device 20, the first bypass valve 25 and the first equalizing valve 26 are closed.

[0067] When the first compressor 21 is operating, the gas refrigerant discharged from the first compressor 21 flows into the first condenser 22, where it is condensed and liquefied, and then reduced in pressure by the first expansion valve 23 and supplied to the first evaporator 123, so that the air blown to the cargo compartment 111 can be cooled by the first evaporator 123.

[0068] The refrigerant discharge amount (in other words, the refrigerant discharge capacity) of the first compressor 21 is controlled based on the temperature in the cargo compartment 111 detected by the cargo compartment temperature sensor 41, the temperature of the first evaporator 123 detected by the first evaporator temperature sensor 45, etc.

[0069] A defrosting operation is performed when it is determined that frost has formed on the first evaporator 123. For example, when the time during which the temperature of the first evaporator 123 detected by the first evaporator temperature sensor 45 is equal to or lower than the frost determination temperature becomes equal to or longer than the frost determination time, it is determined that frost has formed on the first evaporator 123.

[0070] In the defrosting operation, the first bypass valve 25 is opened. As a result, high-temperature gas refrigerant discharged from the first compressor 21 is introduced into the first evaporator 123 through the first bypass passage 27, so that the first evaporator 123 is defrosted.

[0071] When the cab air-conditioning operation switch on the operation panel 50 is turned on, the second compressor 31 operates to operate the cab air-conditioning refrigeration cycle device 30. During normal operation of the cab air-conditioning refrigeration cycle device 30, the second bypass valve 35 and the second pressure equalizing valve 36 are closed. The gas refrigerant discharged from the second compressor 31 flows into the second condenser 32 and is condensed and liquefied, and then is decompressed by the second expansion valve 33 and supplied to the second evaporator 133, so that the air to be blown to the cab 10 can be cooled by the second evaporator 133.

[0072] The refrigerant discharge amount (in other words, the refrigerant discharge capacity) of the second compressor 31 is controlled based on the temperature inside the vehicle cabin detected by the vehicle cabin temperature sensor 42, the outside air temperature detected by the outside air temperature sensor 43, the amount of solar radiation inside the vehicle cabin detected by the solar radiation sensor 44, and the temperature of the second evaporator 133 detected by the second evaporator temperature sensor 46, etc.

[0073] A defrosting operation is performed when it is determined that frost has formed on the second evaporator 133. For example, when the time during which the temperature of the second evaporator 133 detected by the second evaporator temperature sensor 46 is equal to or lower than the frost determination temperature becomes equal to or longer than the frost determination time, it is determined that frost has formed on the second evaporator 133.

[0074] In the defrosting operation, the second bypass valve 35 is opened. As a result, the high-temperature gas refrigerant discharged from the second compressor 31 is introduced into the second evaporator 133 through the second bypass passage 37, so that the second evaporator 133 is defrosted.

[0075] Next, a description will be given of the pressure equalization control and the engine load control shown in the time chart of Fig. 4. For the sake of simplicity, the time chart of Fig. 4 shows the pressure equalization control and the engine load control when the second compressor 31 is stopped.

[0076] When the driver depresses the brake pedal and it is determined that the brake negative pressure is insufficient (when it is determined as NG in the time chart of FIG. 4), the air conditioning control device 40 performs pressure equalization control and engine load control.

[0077] In this example, it is determined whether or not the driver is depressing the brake pedal based on the detection signal of the brake switch 48. In this example, when it is determined based on the detection signal of the intake pressure sensor 47 that the negative pressure of the intake air of the gasoline engine 2 is smaller than a predetermined value (i.e., the negative pressure is closer to 0 than the predetermined value), it is determined that the brake negative pressure is insufficient.

[0078] The engine load control is a control for stopping the first compressor 21 for a predetermined stop time T1. The predetermined stop time T1 is set in advance as the time required for the negative pressure detected by the intake pressure sensor 47 to reach a normal value. The predetermined stop time T1 is, for example, about 2 to 3 seconds.

[0079] Since the load on the gasoline engine 2 is reduced by the engine load control, the negative pressure of the intake air pressure increases and returns to the normal negative pressure.

[0080] The pressure equalization control is a control for opening the first equalization valve 26 and the first bypass valve 25 for a predetermined valve open time T2. The predetermined valve open time T2 is longer than the predetermined stop time T1. The predetermined valve open time T2 is, for example, about 5 seconds. When the stop time of the first compressor 21 reaches the predetermined stop time T1, the first compressor 21 is operated.

[0081] By performing pressure equalization control while the first compressor 21 is stopped, the high pressure and low pressure of the luggage compartment air-conditioning refrigeration cycle device 20 are equalized. Since the first compressor 21 is restarted in a state in which the high pressure and low pressure of the luggage compartment air-conditioning refrigeration cycle device 20 are equalized, it is possible to suppress a large operating noise of the magnetic clutch and abrasion due to slippage of the magnetic clutch when the first compressor 21 is operated.

[0082] When the opening time of the first equalizing valve 26 and the first bypass valve 25 reaches the predetermined opening time T2, the first equalizing valve 26 and the first bypass valve 25 are closed. Since the predetermined opening time T2 is longer than the predetermined stop time T1, it is possible to prevent the first equalizing valve 26 and the first bypass valve 25 from being closed before the first compressor 21 is restarted. Therefore, it is possible to reliably equalize the high pressure and the low pressure in the cargo compartment air-conditioning refrigeration cycle device 20 before the first compressor 21 is restarted.

[0083] In engine load control, the air conditioning control device 40 outputs a request signal to the engine control device 60 to increase the idle speed before the stop time of the first compressor 21 reaches a predetermined stop time T1. When the request signal to increase the idle speed is input to the engine control device 60, the engine control device 60 increases the idle speed of the gasoline engine 2 above a normal idle speed.

[0084] As a result, when the stop time of the first compressor 21 reaches the predetermined stop time T1, the idle speed of the gasoline engine 2 is higher than the normal idle speed, so that even if the load on the gasoline engine 2 increases when the first compressor 21 is operated and the idle speed drops, the idle speed can be prevented from becoming lower than normal. Therefore, it is possible to prevent the operation of the gasoline engine 2 from becoming unstable when the first compressor 21 is operated.

[0085] It should be noted that the idle speed shown in the time chart of FIG. 4 is the idle speed set by the engine control device 60 (in other words, the target idle speed), and the actual idle speed changes with a delay compared to the idle speed shown in the time chart of FIG. 4.

[0086] The timing at which the air conditioning control device 40 outputs a request signal to the engine control device 60 to increase the idle speed is determined taking into consideration the time lag until the idle speed actually changes.

[0087] The rotation speed when the idle speed is increased is set to a rotation speed that can prevent the operation of the gasoline engine 2 from becoming unstable when the first compressor 21 is operated. For example, the rotation speed when the idle speed is increased is preferably set to a rotation speed that can prevent the gasoline engine 2 from stopping (so-called stalling) when the first compressor 21 is operated.

[0088] When the stop time of the first compressor 21 has elapsed for the predetermined stop time T1 and the first compressor 21 is restarted, the air conditioning control device 40 stops outputting a request signal to the engine control device 60 to increase the idle speed. This causes the engine control device 60 to perform normal idle speed control. That is, while the first compressor 21 is operating, the rotation speed of the gasoline engine 2 is controlled to a speed higher than the normal idle speed, and when the first compressor 21 is stopped, the rotation speed of the gasoline engine 2 is controlled to the normal idle speed.

[0089] In this embodiment, when the brake pedal is depressed and the negative pressure of the intake air of the gasoline engine 2 is smaller than a predetermined value, the air conditioning control device 40 performs engine load control to control the magnetic clutch of the first compressor 21 so that the driving force from the gasoline engine 2 is cut off and the first compressor 21 stops, and also performs pressure equalization control to open the first pressure equalization valve 26 so that the suction side and discharge side of the first compressor 21 are connected.

[0090] According to this, when the brake pedal is depressed and the negative pressure of the intake air of the gasoline engine 2 is smaller than a predetermined value, the first compressor 21 is stopped, thereby making it possible to avoid stopping the first compressor 21 when the brake pedal is not depressed.

[0091] Furthermore, when the brake pedal is depressed and the negative pressure of the intake air of the gasoline engine 2 is lower than a predetermined value, the first equalizing valve 26 is opened, so that the high and low pressures of the refrigeration cycle can be equalized while the first compressor 21 is stopped. Therefore, the first compressor 21 can be restarted with the pressure inside the first compressor 21 at an extremely low level, so that it is possible to suppress loud operating noise when the gasoline engine 2 and the first compressor 21 are connected by the magnetic clutch, and to suppress wear due to slippage of the magnetic clutch.

[0092] As a result of the above, it is possible to reduce the frequency with which the first compressor 21 is stopped, and to facilitate the restart of the first compressor 21.

[0093] In this embodiment, when the stop time of the first compressor 21 in the engine load control becomes equal to or longer than the predetermined stop time T1, the air conditioning control device 40 controls the magnetic clutch so that the driving force is transmitted to the first compressor 21, and ends the engine load control. This makes it possible to restart the first compressor 21 with simple control.

[0094] In this embodiment, when the opening time of the first equalizing valve 26 during the pressure equalizing control becomes equal to or longer than the predetermined opening time T2, the air conditioning control device 40 closes the first equalizing valve 26 and ends the pressure equalizing control. This makes it possible to close the first equalizing valve 26 with simple control and return the cargo compartment air conditioning refrigeration cycle device 20 to normal operation.

[0095] In this embodiment, the predetermined open time T2 of the first pressure equalizing valve 26 is longer than the predetermined stop time T1 of the first compressor 21. This makes it possible to prevent the first pressure equalizing valve 26 and the first bypass valve 25 from being closed before the first compressor 21 is restarted, so that the high pressure and low pressure in the cargo compartment air-conditioning refrigeration cycle apparatus 20 can be reliably equalized before the first compressor 21 is restarted. The high pressure and low pressure in the cargo compartment air-conditioning refrigeration cycle apparatus 20 can be equalized before the first compressor 21 is restarted.

[0096] In this embodiment, in pressure equalization control, the air conditioning control device 40 opens the first pressure equalization valve 26 and also opens the first bypass valve 25 so that the refrigerant discharged from the first compressor 21 bypasses the first condenser 22 and the first expansion valve 23 and is guided to the first evaporator 123.

[0097] As a result, in the pressure equalization control, the high pressure and low pressure of the luggage compartment air-conditioning refrigeration cycle device 20 can be equalized also through the first bypass passage 27, so that the high pressure and low pressure of the refrigeration cycle can be reliably equalized.

[0098] In this embodiment, during pressure equalization control, when the open time of the first pressure equalization valve 26 becomes equal to or longer than the predetermined open time T2, the air conditioning control device 40 closes the first pressure equalization valve 26 and also closes the first bypass valve 25, thereby terminating the pressure equalization control.

[0099] As a result, the first equalizing valve 26 and the first bypass valve 25 can be closed with simple control, and the cargo compartment air-conditioning and refrigeration cycle device 20 can be returned to normal operation.

[0100] In this embodiment, when ending the engine load control, the air conditioning control device 40 increases the idle speed of the gasoline engine 2 and then operates the first compressor 21.

[0101] According to this, since the first compressor 21 is operated with the idle speed of the gasoline engine 2 increased, it is possible to prevent the idle speed of the gasoline engine 2 from becoming lower than normal even if the load on the gasoline engine 2 becomes high when the first compressor 21 is operated. Therefore, it is possible to prevent the operation of the gasoline engine 2 from becoming unstable when the engine load control is terminated.

[0102] (Other embodiments) The present invention is not limited to the above-described embodiment, but can be modified in various ways as follows.

[0103] (1) In the above-described embodiment, the air conditioning control device 40 performs pressure equalization control when the first compressor 21 is stopped due to engine load control, but pressure equalization control may also be performed when the first compressor 21 is stopped, regardless of the engine load control.

[0104] For example, the air conditioning control device 40 may perform pressure equalization control during a thermo-out state. A thermo-out state refers to the first compressor 21 being stopped because the temperature in the luggage compartment 111 has reached a target temperature.

[0105] For example, the air conditioning control device 40 may perform pressure equalization control when the first compressor 21 is stopped by an occupant operating a luggage compartment air conditioning operation switch.

[0106] As a result, the high pressure and the low pressure of the refrigeration cycle can be equalized while the first compressor 21 is stopped, so that the first compressor 21 can be restarted in a state where the pressure inside the first compressor 21 is as low as possible, and thus the restart of the first compressor 21 can be facilitated. For example, even when the first compressor 21 is restarted at a relatively short time interval after the first compressor 21 is stopped, the restart of the first compressor 21 can be facilitated.

[0107] (2) In the above embodiment, the air conditioning control device 40 and the engine control device 60 are independent control devices, but the air conditioning control device 40 and the engine control device 60 may be integrated into one control device.

[0108] (3) In the above embodiment, the engine load control shown in the time chart of FIG. 4 is terminated at the specified stop time T1. However, the engine load control may also be terminated when the negative pressure of the intake air of the gasoline engine 2 becomes equal to or greater than a specified value.

[0109] In the above-described embodiment, the pressure equalization control shown in the time chart of FIG. 4 is terminated at the specified valve opening time T2, but the pressure equalization control may also be terminated when the differential pressure between the high pressure and the low pressure of the cargo space air conditioning and refrigeration cycle device 20 becomes equal to or less than a specified pressure.

[0110] (4) In the above embodiment, the engine load control and the pressure equalization control shown in the time chart of Fig. 4 are executed for the luggage compartment air-conditioning refrigeration cycle device 20. That is, in the engine load control, the first compressor 21 is stopped, and in the pressure equalization control, the first equalization valve 26 and the first bypass valve 25 are opened.

[0111] In contrast to this, the engine load control and the pressure equalization control shown in the time chart of Fig. 4 may be executed for the cab air-conditioning refrigeration cycle device 30. That is, in the engine load control, the second compressor 31 may be stopped, and in the pressure equalization control, the second equalization valve 36 and the second bypass valve 35 may be opened.

[0112] (5) In the above-described embodiment, the engine load control is a control for stopping the first compressor 21 or the second compressor 31. However, the engine load control may be a control for stopping on-board equipment such as the alternator 4, a sub-alternator (not shown), a hydraulic pump (not shown), a water pump (not shown), etc.

[0113] The alternator 4 is a generator driven by the gasoline engine 2. The power generated by the alternator 4 is used to charge the on-board battery. The sub-alternator is a generator driven by the gasoline engine 2. The power generated by the sub-alternator is used to charge the on-board sub-battery. The hydraulic pump is a pump that is driven by the gasoline engine 2 to generate hydraulic pressure. The water pump is a pump that is driven by the gasoline engine 2 to circulate cooling water.

[0114] That is, the engine load control may be any control that stops the in-vehicle equipment that applies a load to the gasoline engine 2. As a result, when the brake pedal is depressed and the negative pressure of the intake air of the gasoline engine 2 is smaller than a predetermined value, the load on the gasoline engine 2 is reduced by stopping the in-vehicle equipment, so that the negative pressure of the intake air increases and returns to the normal negative pressure.

[0115] Since the on-board equipment is stopped when the brake pedal is depressed and the negative pressure of the intake air of the gasoline engine 2 is smaller than a predetermined value, the frequency of stopping the on-board equipment can be reduced compared to when the on-board equipment is stopped regardless of whether the brake pedal is depressed when the negative pressure of the intake air of the gasoline engine 2 is smaller than a predetermined value.

[0116] It is desirable that the on-board devices to be stopped in the engine load control are devices that do not immediately affect the running of the vehicle even if they are stopped. This makes it possible to reduce the frequency of stopping the on-board devices without compromising the safety of the running of the vehicle.

[0117] (6) In the above-described embodiment, an HFC refrigerant (specifically, R134a) having low ozone depletion potential is used as the refrigerant for the refrigeration cycle device. However, the refrigerant is not limited to this, and various other refrigerants (for example, so-called new refrigerants having low global warming potential) may be used.

[0118] (7) In the above-described embodiment, the refrigeration cycle devices include a luggage compartment air conditioning refrigeration cycle device 20 and a cab air conditioning refrigeration cycle device 30, but the present invention is not limited to this and may include refrigeration cycle devices for various purposes.

[0119] Further, in the above embodiment, an example in which the refrigeration cycle device is applied to the transport vehicle 1 has been described, but the present invention is not limited to this, and the refrigeration cycle device can be applied to various vehicles. [Explanation of symbols]

[0120] 21 First compressor (compressor, on-board equipment) 22 First condenser (radiator) 23 First expansion valve (pressure reducing section) 25 First bypass valve (bypass valve) 26 1st pressure equalization valve (pressure equalization valve) 27 First bypass flow path (bypass section) 28 1st pressure equalization flow path (pressure equalization section) 40 Air conditioning control device (control unit) 123 First evaporator (evaporator)

Claims

1. a control unit (40) that performs engine load control to stop an in-vehicle device (4, 21) that applies a load to the gasoline engine (2) when a brake pedal, the operation force of which is reduced by a brake booster that utilizes a negative pressure of the intake air of the gasoline engine (2), is depressed and the negative pressure is smaller than a predetermined value; When the control unit (40) terminates the engine load control, the control unit (40) increases the idle speed of the gasoline engine (2) and then operates the in-vehicle device (4, 21).

2. a compressor (21) driven by a gasoline engine (2) for sucking, compressing and discharging a refrigerant; a radiator (22) for radiating heat from the refrigerant discharged from the compressor (21); a pressure reducing section (23) for reducing the pressure of the refrigerant whose heat has been radiated by the radiator (22); an evaporator (123) that evaporates the refrigerant decompressed in the decompression section (23); a control unit (40) that performs engine load control to stop the compressor (21) when a brake pedal, the operation force of which is reduced by a brake booster that utilizes a negative pressure of the intake air of the gasoline engine (2), is depressed and the negative pressure is smaller than a predetermined value; When the control unit (40) terminates the engine load control, the control unit (40) increases the idle speed of the gasoline engine (2) and then operates the compressor (21).

3. a pressure equalizing section (28) for equalizing pressure by communicating the suction side and the discharge side of the compressor (21); a pressure equalizing valve (26) for opening and closing the pressure equalizing section (28), 3. The vehicle refrigeration cycle device according to claim 2, wherein the control unit (40) performs pressure equalization control to open the pressure equalization valve (26) so that a suction side and a discharge side of the compressor (21) communicate with each other when the compressor (21) is stopped.

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