JPS629452B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for a vehicle cooling system that uses a vehicle engine to also drive a compressor, and is capable of controlling the load for driving the compressor without applying sudden torque fluctuations. This prevents the engine from overheating and contributes to fuel efficiency and improved acceleration of the vehicle.

In conventionally known vehicle cooling systems, engine power is transmitted to a compressor pulley via a V-belt. The refrigerant filled in the refrigeration cycle is compressed by a compressor and becomes a high-temperature, high-pressure gas.
This compressed refrigerant gas is forcibly cooled by a condenser and liquefied. Then, the liquefied refrigerant rapidly expands in the expansion valve, becomes a low-temperature, low-pressure mist of refrigerant, and flows into the evaporator.

In the evaporator, the refrigerant passes through a large number of fins, absorbs latent heat of vaporization from the surroundings, evaporates, becomes the original gaseous refrigerant, and is sucked into the compressor again. In addition,
The compressor is equipped with an electromagnetic clutch that is integrated with the pulley, and the operation of the compressor is controlled by intermittent current to the electromagnetic clutch, and this control is based on the engine speed and intake pipe. Negative pressure/
Many of them detect the acceleration of the vehicle and perform automatic control.

By the way, in the control device for a vehicle cooling system having the above-mentioned conventional configuration, a detector that detects the state of the engine is used to control the electromagnetic clutch in specific areas of engine operation (when the engine is running at low speeds, high speeds, or when suddenly accelerating). Cut off the electricity and stop the compressor operation.
It reduces the load on the engine. here,
The torque for driving the compressor is extremely large, 0.5
Kg·m to 1.5 Kg·m is required, and intermittent engagement of the electromagnetic clutch while the engine is running will lead to fluctuations in engine rotation, resulting in an unpleasant shock to the vehicle driver. Furthermore, since the compressor stops completely, no cooling effect can be expected; therefore, controlling only intermittent operation of the compressor is insufficient to meet not only the demands of the engine but also the diversifying demands of cooling users. The current situation is that we are unable to respond adequately.

The present invention has been made in view of the above-mentioned circumstances.The present invention detects the state of the engine and appropriately controls the operating load of the air conditioner, particularly the compressor, using the detected signal, thereby eliminating unpleasant shocks for the vehicle driver. It is possible to prevent the engine from overheating and improve the acceleration of the vehicle without causing any damage or significantly impairing the cooling effect.
Moreover, it is an object of the present invention to provide a control device that can contribute to fuel efficiency.

Specifically, the present invention detects the operating state of the engine using an intake pipe negative pressure detector and an engine rotation speed detector, and uses the intake pipe negative pressure detector to connect the power source to the electromagnetic clutch of the compressor. On the other hand, the engine rotation speed detector is used to operate a refrigerant flow rate control device that controls the flow rate of refrigerant circulating in the refrigeration cycle, and its signal operates a switch circuit. The circuits connecting the power supply and each of the refrigerant flow rate control devices are controlled.

In the above system, the power supply to the electromagnetic clutch of the compressor is stopped under conditions that require the most torque on the engine side, such as sudden acceleration or climbing, in other words, when the engine's intake pipe negative pressure is low (high load operation). time), at which time the compressor is completely stopped. On the other hand, most of the conditions for operating each of the refrigerant flow rate control devices described above are when the engine is under light load or medium load and the engine speed is high. At this time, the compressor is rotating at high speed, so there is sufficient cooling capacity, and the refrigerant flow control device is operated to reduce the refrigerant flow rate, ensuring vehicle drivability even if the cooling capacity is reduced to some extent. I would like to save on fuel consumption. There are also conditions where the above two controls are performed at the same time, that is, the engine rotates at high speed and high load, but in this case, the electric circuit only stops the compressor and does not operate the refrigerant flow control device. can also be configured.

The present invention will be described below with reference to embodiments shown in the drawings. FIG. 1 is a system diagram showing the refrigeration cycle and control system of the cooling device according to the present invention, where 1 is a compressor;
It is operated by transmitting power from a vehicle engine (not shown) via an electromagnetic clutch 2 to a pulley 3, which is integrally formed with the electromagnetic clutch 2, via a belt. The refrigerant gas in the refrigeration cycle is compressor 1
After being sucked in through the suction valve 4 and compressed, it is discharged through the discharge valve 5. The high-temperature, high-pressure gas refrigerant from the compressor 1 flows into the condenser 6, where it is forcibly cooled and condensed by a fan 6a. The liquefied refrigerant is rapidly expanded by the expansion valve 7, takes away the latent heat of vaporization from the air blown by the fan 8a in the evaporator 8 disposed downstream of the liquefied refrigerant, evaporates, becomes gas, and is sucked into the compressor 1 again. The air blown by the fan 8a is cooled by the evaporator 8, becomes cold air, and is blown into the vehicle interior. On the other hand, in the engine operating range detected by the engine's intake pipe negative pressure detector 9 (not shown), that is, under high load conditions such as sudden acceleration and hill climbing, the contact 9a of this detector 9 closes and the relay circuit 10 is activated to cut off the current flowing from the on-vehicle power supply 11 to the electromagnetic clutch 2 of the compressor 1. As a result, the driving performance of the vehicle can be improved by removing the compressor drive load during high-load engine operation. In addition, when the high speed condition is detected by the engine speed detector 12, the contact 12a closes and the power supply 11 sends a current to the electromagnetic flow control valve 13 disposed in the suction pipe connecting the evaporator 8 and the compressor 1. flows, and the valve closes to a preset opening degree to reduce the amount of refrigerant sucked into the compressor 1.

Therefore, the compression work performed by the compressor 1 is reduced, and the load on the engine is reduced.
The amount of accelerator pedal depression required to drive the vehicle at the same speed is reduced, saving fuel consumption. Furthermore, the reduction in engine load creates more leeway, which is extremely effective in preventing danger.

In this example, the intake pipe negative pressure detector 9 includes the contact 9a and a diaphragm 9b that is displaced in accordance with the intake pipe negative pressure and closes the contact 9a when the intake pipe negative pressure falls below a set value.

In this example, the engine rotation speed detector 12 also detects intermittent pulses A generated on the primary side of the engine ignition circuit.
is introduced into the input terminal 12b, this intermittent pulse A is DA-converted to detect the engine rotation speed, and a rotation speed detection circuit 12c is used which closes the contact 12a when the rotation speed is equal to or higher than a set rotation speed.

It goes without saying that the detectors 9 and 12 are not limited to those described above, since various known types can be used.

FIG. 2 shows the results of an experiment to determine the opening degree of the electromagnetic flow control valve 13. If a solenoid valve for ON/OFF control is used, the suction passage will be completely closed, creating a negative pressure inside the pipe, causing atmospheric air to enter the pipe, which may severely reduce the cooling effect. be. In the experiments conducted by the inventors, for the above reason, the limit of throttling is up to one-third of the passage area when it is fully open, and if the passage area is throttled further, the pipe becomes negative pressure, so the control valve 13 is The lower limit of the opening degree during throttle operation is 1/3 of the passage area when fully opened, and it is preferable to set it in a larger range.

Expressing the above conditions in terms of the pressure on the suction side of the compressor, the gauge pressure is 0 to 0.5Kg/cm ² G, which is 0.5Kg/cm ² G.
It is most preferable to set it to . The horizontal axis in Fig. 2 is time t, and Fig. 2 is an experimental example when the car is run in 10 modes. The shaded area B indicates the settable opening range of the flow control valve 13, and the line C indicates the full disclosure of the flow control valve 13, and line D indicates the flow control valve 13.
This shows when the cross-sectional area of the passage is 1/3 of the fully open area.

In addition, in the above-mentioned embodiment, the case where the electromagnetic flow control valve 13 is provided on the suction side of the compressor 1 as a refrigerant flow rate control device has been explained, but various types may be used as long as they can control the refrigerant flow rate of the refrigeration cycle. can be used as a refrigerant flow rate control device.

As mentioned above, the present invention detects the operating state of the engine, and controls the electromagnetic clutch and the respective refrigerant flow control devices according to the output signal of the detector;
Since the present invention reduces the compression work of the compressor and reduces the load on the engine, the present invention does not completely stop the cooling effect and does not cause sudden torque fluctuations, which may cause discomfort to the vehicle driver. It has extremely excellent effects in that it can prevent engine overheating without causing shock, improve vehicle acceleration performance, and contribute to fuel efficiency.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of a cooling device showing one embodiment of the present invention, and FIG. 2 is an explanatory diagram illustrating experimental results of the present invention. DESCRIPTION OF SYMBOLS 1... Compressor, 2... Electromagnetic clutch, 8... Evaporator, 9... Intake pipe negative pressure detector, 10... Relay circuit, 12... Engine speed detector, 13...
Electromagnetic flow control valve (refrigerant flow control device).

Claims (1)

[Scope of Claims] 1. It has a compressor that is driven by the power of the vehicle engine via an electromagnetic clutch, and the compressor exchanges heat by condensing and evaporating the refrigerant circulating in the refrigeration cycle, thereby producing a cooling effect. A vehicle cooling system comprising: an intake pipe negative pressure detector for detecting the intake pipe negative pressure of the vehicle engine; an engine rotation speed detector for detecting the rotation speed of the vehicle engine; and a refrigerant flow rate control device that controls the flow rate of refrigerant, and when the intake pipe negative pressure of the vehicle engine is lower than a predetermined pressure, the intake pipe negative pressure detector shuts off the electromagnetic clutch of the compressor. By stopping the compressor and operating the refrigerant flow control device by the engine rotation speed detector when the rotation speed of the vehicle engine is equal to or higher than a predetermined rotation speed, and reducing the refrigerant flow rate of the refrigeration cycle, A control device for a vehicle cooling system characterized by reducing the load on a compressor. 2. The vehicle cooling system according to claim 1, wherein the refrigerant flow rate control device is an electromagnetic flow rate control valve provided in the middle of a pipe connecting an evaporator and a compressor of a refrigeration cycle. control device.