JPH0728974Y2 - Air conditioner for vehicle - Google Patents

Description

[Detailed description of the device]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle air conditioner suitable for vehicles equipped with a hydraulic circuit and a refrigeration circuit, for example, working vehicles such as rough lane cranes.

[0002]

2. Description of the Related Art Generally, in the case of a rough terrain crane in which the cabin rotates 360 ° or more, unlike ordinary automobiles, the engine cooling water circulating under the cabin cannot be introduced into the cabin, The cooling water 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 (Actual Application No. 1-1238).
36).

This vehicle air conditioner comprises a hydraulic circuit A and a refrigeration circuit B, and the hydraulic circuit A comprises a hydraulic motor drive circuit A1 and a heating circuit A2. The hydraulic motor drive circuit A1 includes an oil tank 10 and a first hydraulic pump 1
1a and the hydraulic motor 12, and the hydraulic oil in the oil tank 10 is pumped up by the first hydraulic pump 11a, and the hydraulic motor 12 is driven by the pumped hydraulic oil. still,
A safety valve 13 limits the pressure applied 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. At this time, the working oil flows to the radiator 15 via 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 causes a pressure difference between the inlet side and the outlet side,
The downstream hydraulic oil is designed to generate heat.

The refrigeration circuit B includes a compressor 20, a condenser 21, and
The liquid receiver 22, the expansion valve 23, and the evaporator 24 are sequentially connected, and the condenser 21 and the evaporator 24 are configured to forcibly exchange heat of air by the blower fans 21a and 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 from the compressor 20, the solenoid valve 16 is closed, and the blower fan 24a. To drive.

At this time, in the hydraulic motor drive circuit A1, hydraulic oil flows to drive the hydraulic motor 12 as shown by the broken line arrow in FIG. 5, but the compressor 20 is stopped. . Further, the hydraulic oil pumped up by the second hydraulic pump 11b is sequentially 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 valve 14, and the working 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 is supplied to the hydraulic motor 12 as shown by the broken line arrow in FIG.
Cycle to drive this. The compressor 20 is driven by the rotational force of the hydraulic motor 12, and the refrigerant discharged from the compressor 20 is condensed from the condenser 21 to the receiver 22 as shown by the solid arrow.
→ The expansion valve 23 → the evaporator 24 → the compressor 20 are sequentially circulated. As a result, the air in the air conditioning air passage 26 is cooled by the evaporator 24, and the cabin is cooled.

When performing dehumidifying heating operation during the rainy season, etc.,
The clutch mechanism 25 connects the hydraulic motor 12 and the compressor 20, closes the electromagnetic valve 14, and drives the blower fans 21a and 24a. As a result, the refrigerant discharged from the compressor 20 circulates as indicated by the solid line arrow as in the cooling operation, and the evaporator 24 dehumidifies and cools the air in the air conditioning air passage 26. Further, the hydraulic oil pumped up by the second hydraulic pump 11b circulates as shown by the broken line arrow as in the heating operation, and the radiator 15 causes the air conditioning air passage 26 to flow.
The air inside is heated. By the dehumidifying cooling by the evaporator 24 and the heating by the radiator 15, the dehumidifying and heating in the cabin is performed.

[0010]

By the way, in the conventional vehicle air conditioner, an electromagnetic proportional type or the like is used as the relief valve 14, and the opening degree of the valve is adjusted based on the temperature detected by the temperature sensor or the like. It is possible to perform automatic control operation, but since the hydraulic oil has a small specific heat,
Due to a sudden change in the pressure difference, the temperature temporarily rises or falls too much, so-called overshoot occurs. At this time, when 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 temperature once lowered rises to the stable temperature. It takes a long time. Therefore, when lowering the target value, there is a problem that the blown air is temporarily too cold and causes an occupant in the vehicle to feel uncomfortable.

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

[0012]

In order to achieve the above-mentioned object, the present invention is provided on the downstream side of a hydraulic pump in a hydraulic circuit.
A relief valve that causes a pressure difference in hydraulic oil and a radiator that radiates the heat of the hydraulic oil generated by the pressure difference are sequentially connected, and the vehicle air is placed in an air-conditioning air passage that leads to the inside of the vehicle. In the harmony device, a temperature detecting means for detecting the temperature of the air in the vehicle and a control means for changing the relief pressure of the relief valve based on the temperature detected by the temperature detecting means are provided, and the relief valve is released.
It is set longer than the time required to lower the pressure.

[0013]

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 conditioned so as to approach the desired temperature. At this time, the time required to lower the relief pressure of the relief valve is set longer than the time required to raise the relief pressure.
Is eliminated, and temporary overcooling of the hydraulic oil temperature is prevented.

[0014]

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

This hydraulic circuit C is a hydraulic motor drive circuit C.
1 and a heating circuit C2. The hydraulic motor drive circuit C1 includes a first oil tank 30a and a first hydraulic pump 3
1a and a hydraulic motor 32, the hydraulic oil in the first oil tank 30a is pumped up by the first hydraulic pump 31a, and 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 includes a second oil tank 30b, a second hydraulic pump 31b, an electromagnetic proportional relief valve 34,
It has a radiator 35 and a normally open solenoid 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 is allowed to flow 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 hydraulic oil between the inlet side and the outlet side to heat the hydraulic oil.
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), Δ
P: 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 amount of heat generated by the relief valve 34 is proportional to the set pressure of the relief valve 34 (hereinafter referred to as the relief pressure).

In the refrigeration circuit D, as in the conventional example shown in FIG. 4, a compressor 40, a condenser 41, a liquid receiver 42, and an expansion valve 4 are provided.
3, the evaporator 44 is sequentially connected, and the condenser 41 and the evaporator 44 are forcibly exchanged with each other by the blower fans 41a and 44a. 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 vehicular air conditioner according to this embodiment is mounted on the rough terrain crane. That is, the air conditioning unit 51 is installed in the cabin 50.
Is installed, and the air conditioning air passage 5 in this air conditioning unit 51 is installed.
Blower fan 44a, evaporator 44 and radiator 35
Has been installed. Further, this air conditioning air passage 52 is provided with a damper 53.
Thus, the air passage for heating and the air passage for cooling can be switched. That is, during heating and dehumidifying 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 out into the cabin 50 through the evaporator 44 and the radiator 35, and during cooling, the dashed arrow. As shown in FIG. 5, the air 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 stepwise according to the program described later. Switch. Further, the control unit 60 controls the time T required to decrease the relief pressure P of the relief valve 34 by one step.
₁ is set to be longer than the time T ₂ required to raise it by one step. For example, T ₁ is 6 seconds and T ₂ is 0.375 seconds.

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

At this time, in the hydraulic motor drive circuit C1, the hydraulic oil flows as shown by the broken line arrow in FIG. 1 to drive the hydraulic motor 32, but the compressor 40 is stopped. . In addition, the hydraulic oil pumped up by the hydraulic pump 31b, as indicated by the broken line arrow in FIG.
It circulates in the order of 4 → radiator 35 → second oil tank 30b.
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 valve 34, and the working 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 the cooling operation is performed in the summer, the clutch motor 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 indicated 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 a solid arrow, a condenser 41 → a liquid receiver 42 → an expansion valve 43 → an evaporator 44 → It circulates in sequence with the compressor 40. This causes the air in the air conditioning circuit 52 to move to the evaporator 4
The inside of the cabin 50 is cooled by cooling at 4.
The connection and release of the clutch mechanism 45 at this time is performed by the control unit 6
0 controls based on the detected temperature of the temperature sensor 55 and the set temperature input to the operation unit (not shown).

When performing dehumidifying heating operation during the rainy season, etc.,
The clutch mechanism 45 repeatedly connects the hydraulic motor 32 and the compressor 40 for a predetermined time Ta and releases the predetermined time Tb, closes the solenoid valve 36, and blows the fan 41a (only when the clutch mechanism 45 is connected. (Operation) and the blower fan 44a is driven. As a result, the refrigerant discharged from the compressor 40 circulates as indicated by the solid line arrow as in the cooling operation, and the evaporator 44 dehumidifies and cools the air in the air conditioning air passage 52. 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 radiator 35 heats the air in the air conditioning air passage 52. Dehumidifying cooling by this evaporator 44 and radiator 3
By heating by 4, the dehumidifying and heating of the cabin 50 is performed.

The operation of the controller 60 during the heating or dehumidifying heating operation will be described with reference to the flowchart shown in FIG.

First, when the temperature t detected by the temperature sensor 55 is smaller than the set temperature t ₀ by a small value β (S1),
If the value is smaller than the set temperature t ₀ by a small 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 a minute value β in step S1, the relief pressure P of the relief valve 34 is increased by a minute value α (S3). At this time, it takes time T ₂ for the relief pressure P to reach P + α.
_It waits for a time of only ₂ (S4), and returns to step S1 again. When the detected temperature t exceeds the set temperature t ₀ by a small value β in step S1,
The relief pressure P of the relief valve 34 is reduced by a minute value α (S5). At this time, it takes time T ₁ for the relief pressure P to reach P-α, so 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 with 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 the temperature rises steeply and the relief occurs.
Overshoot occurs when the pressure reaches P-α to P, but the overshoot when the temperature rises is eliminated quickly, so the temperature rapidly drops to a stable temperature. On the other hand, release
It is assumed that when the pressure P is decreased by a minute value α, the same required time T ₂ as when it is increased 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 an overshoot occurs when the relief pressure reaches from P to P-α. When the temperature is lowered, the overshoot is large unlike when the temperature is raised, and it takes a long time to rise to the 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 required time T _{2 for} raising the relief pressure P is applied, and as shown by the solid line in FIG. Overshoot rarely occurs. still,
There is no problem if the relief pressure P is raised and lowered both in the required time T ₁ , but in order to obtain a quick heating effect, the relief pressure P is intentionally raised in a short time. preferable.

As described above, according to the vehicle air conditioner of this embodiment, the relief pressure P of the relief valve 34 is controlled stepwise on the basis of the temperature t detected by the temperature sensor 55, and the relief pressure is released. Since the time T ₁ required for lowering the pressure P by one step is set longer than the time T ₂ required for increasing it by one step, it is possible to realize an accurate automatic control operation with less influence of overshoot. Therefore, a comfortable air-conditioned space can be provided.

[0029]

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, so that comfortable air conditioning is achieved. Space can be provided.

[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 temperature change 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)

[Scope of utility model registration request] 1. A release valve for causing a pressure difference in hydraulic oil and a radiator for radiating the heat of the hydraulic oil generated by the pressure difference are sequentially connected to the downstream side of the hydraulic pump in the hydraulic circuit, and the heat radiation is performed. In a vehicle air conditioner in which an air conditioner is arranged in an air-conditioning air passage leading to the inside of a vehicle, temperature detecting means for detecting the temperature of the air inside the vehicle, and a relief pressure of the relief valve based on the temperature detected by the temperature detecting means. And a control means for changing the release pressure, and is set longer than the time required to increase the time required to reduce the relief pressure of the relief valve.