JPH0510022U - Air conditioner for vehicle - Google Patents

Abstract

(57) [Abstract] [Purpose] To prevent overshoot when lowering the relief pressure of the relief valve and realize automatic control operation without temporary overcooling. [Composition] The relief pressure of the relief valve 34 is controlled stepwise based on the temperature t detected by the temperature sensor 55, and the time T ₂ required to raise the time T ₁ required to lower the relief pressure is increased. It is set longer than that to prevent overshoot when the temperature drops.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a vehicle air conditioner suitable for a vehicle having a hydraulic circuit and a refrigeration circuit, for example, a working vehicle such as a rough lane crane.

[0002]

[Prior Art]

 In general, in the case of a rough terrain crane in which the cabin rotates 360 ° or more, unlike ordinary automobiles, the engine cooling water that circulates below the cabin cannot be introduced into the cabin, and this engine cooling water cannot be introduced. It cannot be used as a heat source for heating. Therefore, the applicant has proposed an air conditioner for cooling and heating such a vehicle as shown in FIG. 7 (Japanese Patent Application No. 1-123836).

This vehicle air conditioner comprises a hydraulic circuit A and a refrigeration circuit B, and the hydraulic circuit A is composed of a hydraulic motor drive circuit A1 and a heating circuit A2. The hydraulic motor drive circuit A1 has an oil tank 10, a first hydraulic pump 11a, and a hydraulic motor 12, and hydraulic oil in the oil tank 10 is pumped up by the first hydraulic pump 11a and pumped up. The hydraulic motor 12 is driven by the obtained hydraulic oil. Incidentally, 13 is a safety valve for limiting the pressure to the hydraulic motor 12.

The heating circuit A2 has an oil tank 10, a second hydraulic pump 11b, a relief valve 14, a radiator 15, and a normally open solenoid valve 16. When the solenoid valve 16 is open, the hydraulic oil pumped up by the second hydraulic pump 11b returns directly to the oil tank 10 via the solenoid valve 16, and the solenoid valve 16 is closed. When operating, the working oil flows to the radiator 15 through the relief valve 14. The hydraulic pumps 11a and 11b are driven by the engine of the vehicle, and the hydraulic oil is also supplied to various hydraulic actuators (not shown). Further, the relief valve 14 is adapted to generate a pressure difference between the inlet side and the outlet side to heat the working oil on the downstream side.

The refrigeration circuit B comprises a compressor 20, a condenser 21, a liquid receiver 22, an expansion valve 23, and an evaporator 24, which are sequentially connected to each other. The condenser 21 and the evaporator 24 are provided with a blower fan 21 a, respectively. Air heat exchange is forced by 24a. The compressor 20 is connected to the hydraulic motor 12 via a clutch mechanism 25. Further, the blower fan 24a is installed in an air conditioning air passage 26 that guides air conditioning air into the cabin.

In this vehicle air conditioner, when the heating operation is performed in the winter, the clutch mechanism 25 disconnects the hydraulic motor 12 and the compressor 20, and the solenoid valve 16 is closed to further blow air. The fan 24a is driven.

At this time, in the hydraulic motor drive circuit A1, the hydraulic oil flows to drive the hydraulic motor 12 as shown by the broken line arrow in FIG. 5, but the compressor 20 is in a stopped state. .. Further, the hydraulic oil pumped up by the second hydraulic pump 11b is circulated in the order of the relief valve 14 → the radiator 15 → the oil tank 10 as shown by the broken line arrow in FIG. Here, when the hydraulic oil passes through the relief valve 14, a pressure difference is generated between the inlet side and the outlet side of the relief valve 14, and the hydraulic oil generates heat. The heat of the hydraulic oil is released by the radiator 15 and heats the air in the air conditioning air passage 26 blown by the blower fan 24a. As a result, the cabin is heated.

When the cooling operation is performed in the summer, the clutch motor 25 connects the hydraulic motor 12 and the compressor 20, and further drives the blower fans 21a and 24a. As a result, the hydraulic oil pumped up by the first hydraulic pump 11a circulates and drives the hydraulic motor 12 as shown by the broken line arrow in FIG. The compressor 20 is driven by the rotational force of the hydraulic motor 12, and the refrigerant discharged from the compressor 20 is, as shown by the solid line arrow, condenser 21 → receiver 22 → expansion valve 23 → evaporator 24 → It circulates in sequence with the compressor 20. As a result, the air in the air conditioning air passage 26 is cooled by the evaporator 24, and the inside of the cabin is cooled.

When dehumidifying and heating operation is performed during the rainy season or the like, the clutch motor 25 connects the hydraulic motor 12 and the compressor 20, the solenoid valve 14 is closed, and the blower fans 21a and 24a are connected. To drive. As a result, the refrigerant discharged from the compressor 20 circulates as shown by the solid arrow as in the cooling operation, and the air in the air conditioning air passage 26 is dehumidified and cooled by the evaporator 24. Further, the hydraulic oil pumped up by the second hydraulic pump 11b circulates as indicated by the broken line arrow as in the heating operation, and the radiator 15 heats the air in the air conditioning air passage 26. By the dehumidifying cooling by the evaporator 24 and the heating by the radiator 15, dehumidifying and heating in the cabin is performed.

[0010]

[Problems to be solved by the device]

 By the way, in the conventional vehicle air conditioner, an electromagnetic proportional type or the like is used for the relief valve 14, and automatic control operation is performed to adjust the opening degree of the valve based on the temperature detected by a temperature sensor or the like. However, since the hydraulic oil has a small specific heat, a sudden change in the pressure difference causes the temperature to temporarily rise or fall too much, so-called overshoot. At this time, if the outside air temperature is low, the overshoot at the time of temperature rise disappears relatively quickly and the temperature stabilizes, but at the time of temperature decrease, the once lowered temperature rises to the stable temperature. Takes a long time. For this reason, when lowering the target value, the blown air is temporarily too cold, which causes a discomfort to passengers in the vehicle.

The present invention has been made in view of the above problems, and it is an object of the present invention to prevent overshoot at the time of temperature decrease and to perform an accurate automatic control operation. Another object of the present invention is to provide a vehicle air conditioner.

[0012]

[Means for Solving the Problems]

 In order to achieve the above object, the present invention sequentially provides a relief valve for causing a pressure difference in hydraulic oil and a radiator for radiating heat of the hydraulic oil generated by the pressure difference downstream of the hydraulic pump in the hydraulic circuit. In a vehicle air conditioner in which the radiator is arranged in an air-conditioning air passage leading to the inside of the vehicle, the temperature detecting means for detecting the temperature of the air inside the vehicle and the relay based on the temperature detected by the temperature detecting means are connected. A control means for changing the relief pressure of the relief valve is provided, and the time required to reduce the relief pressure of the relief valve is set longer than the time required to increase it.

[0013]

[Action]

 According to the vehicle air conditioner of the present invention, the relief pressure of the relief valve changes based on the detected temperature of the air inside the vehicle, and the blown air is air-conditioned so as to approach the desired temperature. At that time, since the time required to lower the relief pressure of the relief valve is set longer than the time required to raise it, the overshoot at the time of temperature decrease is eliminated. Therefore, temporary overcooling of the hydraulic oil temperature is prevented.

[0014]

【Example】

 1 to 6 show an embodiment of the present invention, in which C is a hydraulic circuit and D is a refrigeration circuit.

The hydraulic circuit C is composed of a hydraulic motor drive circuit C1 and a heating circuit C2. The hydraulic motor drive circuit C1 has a first oil tank 30a, a first hydraulic pump 31a, and a hydraulic motor 32. The hydraulic oil in the first oil tank 30a is pumped up by the first hydraulic pump 31a, The hydraulic motor 32 is driven by the pumped hydraulic oil. The first hydraulic pump 31a is driven by the engine of the vehicle. Incidentally, 33 is a safety valve for limiting the pressure to the hydraulic motor 32.

The heating circuit C2 has a second oil tank 30b, a second hydraulic pump 31b, an electromagnetic proportional relief valve 34, a radiator 35, and a normally open electromagnetic valve 36 that serves as a switching means. When the solenoid valve 36 is open, the hydraulic oil pumped up by the second hydraulic pump 31b returns directly to the second oil tank 30b via the solenoid valve 36, and the solenoid valve 36 is closed. At this time, the working oil flows to the radiator 35 via the relief valve 34. The second hydraulic pump 31b is connected to the hydraulic motor 32, and is driven by the rotational force of the hydraulic motor 32. Incidentally, 37 is a safety valve for limiting the pressure to the relief valve 34.

The relief valve 34 causes a pressure difference in the working oil between the inlet side and the outlet side, and causes the working oil to generate heat. This calorific value is calculated by the following formula. That is, H = 1.41 × Q × ΔP H: calorific value (kcal / h), Q: hydraulic oil flow rate (l / min), ΔP: pressure difference (kgf / cm ² ) 1.41: constant ΔP = P−P ′ P : Pressure on the inlet side of the relief valve (relief pressure), P ': Pressure on the outlet side of the relief valve Therefore, the calorific value of the relief valve 34 is proportional to the set pressure of the relief valve 34 (hereinafter referred to as the relief pressure). Will be done.

As in the conventional example shown in FIG. 4, the refrigeration circuit D is formed by sequentially connecting a condenser 41, a liquid receiver 42, an expansion valve 43, and an evaporator 44 to a compressor 40. The unit 44 is configured to forcibly exchange heat with air by the blower fans 41a and 44a. Further, the compressor 40 is connected to the hydraulic motor 32 via a clutch mechanism 45.

FIG. 2 is a schematic configuration diagram showing a state in which the vehicle air conditioner according to the present embodiment is mounted on the rough terrain crane. That is, an air conditioning unit 51 is installed in the cabin 50, and an air blowing fan 44a, an evaporator 44, and a radiator 35 are installed in an air conditioning air passage 52 in the air conditioning unit 51. Further, the air conditioning air passage 52 can be switched between a heating air passage and a cooling air passage by a damper 53. That is, during heating and dehumidifying and heating, as shown by the solid arrow, the air in the cabin 50 is sucked in through the intake port 54 of the air conditioning unit 51 and blown into the cabin 50 through the evaporator 44 and the radiator 35, and during cooling. As shown by the broken line arrow, it is blown into the cabin 50 only through the evaporator 44. Reference numeral 55 is a temperature sensor provided on the downstream side of the radiator 35.

FIG. 3 shows a control system of the relief valve 34, and 60 is a control unit having a microcomputer configuration. The control unit 60 is connected to the temperature sensor 55 and the relief valve 34, and can input a set temperature from an operation unit (not shown). The control unit 60 sets the relief pressure P of the relief valve 34 at every minute value α (for example, 50 kgf / cm ² ), and the relief pressure P of the relief valve 34 is set in accordance with the program described later. Switch. Further, the control unit 60 sets the time T ₁ required for lowering the relief pressure P of the relief valve 34 by one step to be longer than the time T ₂ required for raising it by one step. ₁ for 6 seconds, T ₂ for 0. It is set to 375 seconds.

In this embodiment, when heating operation is performed in winter, the clutch mechanism 45 disconnects the hydraulic motor 32 and the compressor 40, and the solenoid valve 36 is closed to drive the blower fan 44a. ..

At this time, in the hydraulic motor drive circuit C1, the working oil flows as shown by the broken line arrow in FIG. 1 to drive the hydraulic motor 32, but the compressor 40 is in a stopped state. There is. Further, the hydraulic oil pumped up by the hydraulic pump 31b is circulated in the order of the relief valve 34 → the radiator 35 → the second oil tank 30b, as shown by the broken line arrow in FIG. Here, when the hydraulic oil passes through the relief valve 34, a pressure difference is generated between the inlet side and the outlet side of the relief valve 34, and the hydraulic oil generates heat. The heat of the hydraulic oil is released by the radiator 35 and heats the air in the air conditioning air passage 52 blown by the blower fan 44a. As a result, the interior of the cabin 50 is heated.

When performing the cooling operation in the summer, the clutch mechanism 45 connects the hydraulic motor 32 and the compressor 40 and drives the blower fans 41a and 44a. As a result, the hydraulic oil pumped up by the first hydraulic pump 31a circulates and drives the hydraulic motor 32, as shown by the broken line arrow in FIG. The compressor 40 is driven by the rotational force of the hydraulic motor 32, and the refrigerant discharged from the compressor 40 is, as indicated by the solid arrow, a condenser 41 → a liquid receiver 42 → an expansion valve 43 → an evaporator 44 → It circulates in sequence with the compressor 40. As a result, the air in the air conditioning circuit 52 is cooled by the evaporator 44, and the cabin 50 is cooled. At this time, the connection and release of the clutch mechanism 45 are controlled by the control unit 60 based on the temperature detected by the temperature sensor 55 and the set temperature input to the operation unit (not shown).

When the dehumidifying and heating operation is performed during the rainy season or the like, the clutch mechanism 45 causes the hydraulic motor 32 and the compressor 40 to repeatedly connect the predetermined time Ta and release the predetermined time Tb, and at the same time, to operate the solenoid valve. 36 is closed, and the blower fan 41a (only operates when the clutch mechanism 45 is engaged) and the blower fan 44a are driven. As a result, the refrigerant discharged from the compressor 40 circulates as shown by the solid arrow as in the cooling operation, and the air in the air conditioning air passage 52 is dehumidified and cooled by the evaporator 44. Further, the hydraulic oil pumped up by the second hydraulic pump 31b circulates as indicated by the broken line arrow as in the heating operation, and the heat radiator 35 heats the air in the air conditioning air passage 52. By the dehumidifying and cooling by the evaporator 44 and the heating by the radiator 34, the dehumidifying and heating in the cabin 50 is performed.

Here, the operation of the control unit 60 during the heating or dehumidifying and heating operation will be described with reference to the flowchart shown in FIG.

First, if the detected temperature t of the temperature sensor 55 is equal to or more than a value smaller than the set temperature t ₀ by a minute value β (S1) and equal to or smaller than a value larger than the set temperature t ₀ by a minute value β (S2 ), The relief pressure P of the relief valve 34 is maintained as it is. When the detected temperature t is lower than the set temperature t ₀ by the small value β in step S1, the relief pressure P of the relief valve 34 is increased by the small value α (S3). At this time, it takes a time T ₂ for the relief pressure P to reach P + α, so the process waits for the time T ₂ (S4) and returns to step S1 again. When the detected temperature t exceeds the value which is smaller than the set temperature t ₀ by the minute value β in step S1, the relief pressure P of the relief valve 34 is decreased by the minute value α (S5). At this time, since it takes time T ₁ for the relief pressure P to reach P-α, the process waits for the time T ₁ (S6) and returns to step S1 again.

The timing chart shown in FIG. 5 and the graph shown in FIG. 6 show changes over time due to the operation of the control unit 60. As shown in FIG. 6, when the relief pressure P of the relief valve 34 is increased by a small value α, the required time T ₂ is short, so that a steep temperature rise occurs and the relief pressure P-α. The overshoot occurs when the temperature reaches from P to P, but the overshoot when the temperature rises is eliminated quickly, so the temperature rapidly drops to the stable temperature. On the other hand, it is assumed that when the relief pressure P is reduced by a minute value α, the same required time T ₂ as when it is raised is applied. In this case, as shown by the broken line in FIG. 6, as in the case of raising the temperature, a steep temperature drop is exhibited, and the overshoot is turned off when the relief pressure reaches from P to P-α. Although it occurs, when the temperature is decreased, the overshoot is large unlike when the temperature is increased, and it takes a long time to increase to a stable temperature. For this reason, the hydraulic oil temporarily becomes too cold, resulting in discomfort to the passenger in the cabin 50. On the other hand, in the present embodiment, when the relief pressure P is lowered, the time T ₁ which is sufficiently longer than the time T ₂ required for raising the relief pressure P is applied, and therefore, as shown by the solid line in FIG. In fact, overshoot rarely occurs. There is no problem if the relief pressure P is both raised and lowered within the required time T ₁ , but in order to obtain a quick heating effect, the relief pressure P is intentionally increased in a short time. It is preferable to carry out.

As described above, according to the vehicle air conditioner of the present embodiment, the relief pressure P of the relief valve 34 is controlled stepwise based on the temperature t detected by the temperature sensor 55. Since the time T ₁ required to lower the relief pressure P by one step is set longer than the time T ₂ required to raise it by one step, accurate automatic control operation with less influence of overshoot can be performed. It can be realized and a comfortable air-conditioned space can be provided.

[0029]

[Effect of the device]

 As described above, according to the vehicle air conditioner of the present invention, it is possible to realize accurate automatic control operation with less influence of overshoot, and thus to provide a comfortable air-conditioned space. You can

[Brief description of drawings]

FIG. 1 is a circuit diagram of a vehicle air conditioner showing an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram showing an installation state of a vehicle air conditioner.

FIG. 3 is a block diagram showing a control system of the vehicle air conditioner.

FIG. 4 is a flowchart showing the operation of the control unit.

FIG. 5 is a timing chart showing changes in pressure difference.

FIG. 6 is a graph showing a change in temperature of hydraulic oil.

FIG. 7 is a circuit diagram of a vehicle air conditioner showing a conventional example.

[Explanation of symbols]

31b ... second hydraulic pump, 34 ... relief valve, 35
... radiator, 52 ... air conditioning air passage, 55 ... temperature sensor, 60 ...
Controller, C ... Hydraulic circuit

Claims (1)

[Claims for utility model registration] Claims: 1. A relief valve for causing a pressure difference in the hydraulic oil downstream of the hydraulic pump in the hydraulic circuit, and a radiator for radiating the heat of the hydraulic oil generated by the pressure difference. In a vehicle air conditioner in which the radiator is arranged in an air-conditioning air passage leading to the inside of the vehicle, temperature detecting means for detecting the temperature of the air inside the vehicle, and A vehicle provided with control means for changing the relief pressure of the relief valve, and is set to be longer than the time required to lower the relief pressure of the relief valve. Air conditioner.