JPS63301118A - Capacity control for variable capacity type compressor - Google Patents

Abstract

PURPOSE:To lighten the engine load without deteriorating the cooling feeling by reducing the capacity of a compressor to the min. for a certain time when the engine load increases and adjusting the reduction quantity of the capacity according to the difference between the detection value of the control quantity and an aimed value. CONSTITUTION:A cooling circuit 1 is constituted of a condenser 3, receiver 4, expansion value 5, and an evaporator 6 connected in succession through pipings 7, in a circuit ranging from the discharge side of a variable capacity type compressor driven by an on-vehicle engine to the suction side. The capacity varying mechanism 8 of the compressor 2 is controlled by a controller 9 on the basis of each signal of a sensor 10 for detecting the blasting-out port temterature of the evaporator 6, sensor 11 for detecting the stepping-on quantity of an accelerating pedal for engine, and a switch 12 for setting the aimed temperature of the car compartment. In this case, if the engine load is increased, the capacity of the compressor is reduced to the min. for a certain time. Then, the reduction quantity of the capacity is adjusted according to the difference between the detection value of the control quantity and the aimed value.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for controlling a variable capacity compressor in a vehicle cooling system.

BACKGROUND ART As shown in FIG. 1, a general cooling circuit 1 installed in a vehicle includes a condensing device 3 between the circuits from the discharge side to the suction side of a variable capacity compressor 2 (hereinafter referred to as the compressor).
A receiver 4, an expansion valve 5, and an evaporator 6 are sequentially connected by a pipe 7.

The compressor 2 is of a wobble type, a rotary set, a swash plate type, etc., and in order to perform this variable control, a temperature sensor 10 is installed at the outlet of the evaporator 6 to detect the outlet temperature of the evaporator 6, which is a controlled variable. In addition, there is a 3-meter meter 11 for detecting the amount of depression of the accelerator pedal to determine the engine load, and a target value setting switch 12 for setting the desired temperature by the driver in the room.
are provided on the operation panel of the cooling device, etc.
Signals from the sensor and switch are input to the control variable N9.

The control device 9 drives the variable capacity mechanism 8 based on the signal to control the capacity of the compressor 2. The variable capacity mechanism 8 is constituted by a solenoid valve or a solenoid depending on the type of the compressor 2, and is configured to displace continuously or stepwise.

Here, the conventional control method for the control device 9 is shown in the flowchart of FIG. 2. First, the power is turned on and started (step 13), and the target value T is inputted from the target value setting switch 12 (step 14). Evaporation r510 as a controlled variable
The detected value T of the outlet temperature is input from the temperature sensor 10 (step 15), and the optimum capacity U of the compressor 2 is determined from these values (step 16).

Next, input the engine load from the potentiometer 11 (step 17), and compare this value with the memorized reference value (step 18). If it is larger, the operation amount U for moving the variable capacity mechanism 8 is calculated based on the optimum capacity U (steer knob 19).

If the reference value is reached in step 18 and l is smaller, the compressor is set to the minimum capacity u1.1 to reduce the engine load, and this is set as the optimum capacity lu, and step 21
), output to step 19 above.

Finally, the variable capacity mechanism is driven based on the manipulated variable U of step 19 (step 20), and the process returns to the beginning to input the next target value TR, and this process is repeated thereafter.

Problems to be Solved by the Invention However, with the above-mentioned conventional technology, there are many times when the engine load is high, such as when sudden acceleration is frequently performed, such as when driving on a city road, or when pitching for a long time. Therefore, the compressor continues to operate at the minimum capacity, and there is a problem that sufficient cooling capacity cannot be obtained, especially during cool-down or when the indoor temperature is higher than the target value, causing the temperature inside the vehicle to rise and significantly impairing the cooling feeling. Ta.

In view of the above-mentioned problems, the present invention aims to solve the problems by reducing the engine load without impairing the cooling feeling even when the engine load is large.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention controls the compressor capacity in order to always keep the room temperature at an appropriate level according to the detected value of the control amount, and also controls the detected value of the engine load to be constant. When the value is exceeded, the compressor capacity is varied to the minimum value, and when the time of the minimum capacity state exceeds a certain period of time, the difference between the detected value of the control amount and the target value is determined, and according to this difference, the compressor capacity is varied. A technical method is adopted to adjust the amount of decrease in compressor capacity.

When the operating engine load increases, the compressor capacity is minimized for a certain period of time within a range that does not impair the cooling feeling to reduce the load on the engine. After that, the amount of decrease in capacity is set to a according to the difference between the detected value and the target value of the controlled variable.
This allows the engine load to be reduced without impairing the cooling feeling.

Embodiment Next, an embodiment in which the present invention is embodied in a variable compressor for a cooling circuit for a vehicle will be described with reference to the drawings. However, since the cooling circuit used in this embodiment is the same as the conventional one as shown in FIG. 1, its explanation will be omitted here.

Next, a method of controlling the compressor in the control device 9 of the cooling circuit 1 shown in FIG. 1 will be described with reference to FIGS. 3 to 5. In the flowchart shown in FIG. 3, first, the power is turned on and the system is started (step 13), and initial values necessary for control (for example, timer time t, fixed time t4.7, etc.) are set.

Here, it is assumed that the timer necessary for determining the timer time t is built into the control device 9, but it may be inputted from outside the control device 9. 1 is set in consideration of the engine output and the rise in the temperature inside the vehicle; for example, in this embodiment, the value is set to 30.
It is set from seconds to 1 minute.

Next, steps 14 to 20 are the same as in the conventional control method, and the explanation thereof will be omitted here.

Now, input the engine load from the potentiometer 11 that detects the amount of displacement of the accelerator, and compare it with the reference value input in advance (step 18). If the engine load is equal to the reference value.

If it is below, proceed to step 23 and compressor capacity U
is replaced by the optimal capacity u1. However, a description of step 22 passed during this time will be given later.

Next, in step 19, the operation amount U of the variable capacity mechanism 8 for varying the capacity of the compressor 2 to the optimum capacity u1 is calculated, and the variable capacity mechanism 8 is driven based on this value (step 20). Further, in order to perform the next control, the process returns to the first step 14 through B and repeats a new operation.

On the other hand, in step 1, if engine load L>reference value, the compressor capacity is changed in order to reduce this engine load.

Therefore, first, the timer time t is compared with a constant time t+min inputted in advance as a reference. For example, in the initial state, the timer time t is a fixed time t, which is smaller than fi, so in this case, the timer is started next (
In step 30), the timer time t is counted and the compressor capacity U is changed to the minimum capacity u, IIn. In step 31), the operation amount U is calculated (step 19). If there is no change in the engine load and the timer time t is also less than the fixed time t11iR, the flowchart of the figure repeats again through the same process through steps 30.31 and the compressor continues to operate at the minimum capacity ulltn.

Then, as time passes, the timer time t is gradually increased, and when it finally reaches t,i,1 or more, from step 18, the input temperature target value T and the detected value T of the air outlet temperature are used. The difference ΔT between these two is determined (step 25), and the capacity is reviewed based on this value (step 26).

Here, the state of step 26 is shown in the graph of FIG. If the difference ΔT is large, the difference from the target value is large and discomfort increases, so the capacity of the compressor must be increased accordingly. However, if you increase it too much, it will adversely affect the engine load, so make sure to keep it at an appropriate capacity. The slope of the straight line in the graph is based on the above viewpoint, and the minimum capacity U1
18. It is set with a moderate slope based on l, and the volume is 1
ut is determined.

Next, counting of the timer time t is stopped and reset to the initial state (=0) (step 27).

Here, since the capacity u2 is not just a Nk capacity, if the capacity U becomes larger than the optimal capacity U obtained earlier, if you continue to operate with the capacity ug, it will cause an increase in the indoor Not only does this result in overcooling, which increases discomfort, but it also puts more load on the engine than necessary, reducing efficiency.

Then, the capacity U and ug are compared (step 2), and if the capacity ful is smaller, this value is sent to the next step 23, the capacity U is replaced with ul, and the process is sent to step 19. If the capacity Ruz is smaller, the capacity U is replaced with u2 (step 29), and this value is sent to the next step 19.

Changes in capacity due to the control method described above are shown in the graph of FIG. 5, in which time is plotted on the horizontal axis and capacity is plotted on the vertical axis.

As shown in this figure, the compressor, which was initially operating at the capacity u1, decreases its capacity at time t as the engine load increases, reaching the minimum capacity, and continues to operate at the minimum capacity 1 uai++ within a certain period of time. (Furthermore, after a certain period of time t, 7, the capacity is reviewed at time t to prevent the cooling feeling from deteriorating, and the capacity u2 between Ll and u,in is The load on the engine can be reduced by 'ttX.Furthermore, after time 1
The engine load reaches the standard value at e, and when it becomes below, the capacity U
returns to its original capacity of 1ul.

By the way, in step 18 in the above process, the engine load L>reference value L++--in step 24, the compressor is operated at the minimum capacity u, i in the state of timer time t and constant time t, A, l. During the engine load changes, the reference value L
It may be less than ll. At this time, the timer time t that has been counting up to that point is stopped from step 18, but the time from start to stop is maintained without resetting (step 22), and the next step is started.・Knob 2
3, the compressor is operated at optimum capacity u1.

If there is no change in the engine load, the optimal capacity 1
The engine continues to operate at ul, but if the engine load L>reference value LM is reached again, step 18 to step 2
4, the timer starts the timer again at the step knob 30 and starts counting from the time t stopped at the previous step knob 22, and through the next step 31, the compressor starts the timer at the minimum capacity u, It is operated by 411.

Then, due to such a change in the engine load, while the compressor capacity repeats u, l, l and U, the sum of the times of the minimum capacity u and 17 states exceeds tsin, from step 24 to step 25. Proceed to and the capacity is reviewed in the same way as above.

The aforementioned change in capacitance is shown in the graph of FIG. This diagram is
For example, this indicates a situation where the vehicle suddenly starts and stops repeatedly in a short period of time, such as in a city area. As shown in the figure, the compressor was initially operated at the optimum capacity U, but as the engine load exceeds the reference value Lx, the capacity is reduced to the minimum capacity i1 ulIi, and after time t1 the engine load increases again. is the reference value, and as soon as it falls below the reference value, the compressor returns to the optimum capacity u1.

Furthermore, at time LX, j3, the same control as above is performed, and the sum of the operating times at the minimum capacity is 1. +1t
+1. When becomes greater than or equal to L sin, the capacity U of the compressor is revised to become the capacity u2.

In this way, the timer time t is set to a certain time tI1. ．． .

For shorter periods, the compressor capacity U is operated either at the optimum capacity U or at the minimum capacity u, i11 depending on the engine load. And the timer time t is a certain time jsi
When the engine load is greater than a and the engine load is large, the engine is operated at the newly revised capacity u2, which impairs the cooling feeling even when sudden starts and stops are repeated in a short period of time as described above. Never.

It should be noted that the present invention is not limited to the above-mentioned embodiments, but may be modified as follows.

(1) The function of storing and adding the operating time at the minimum capacity of the timer time t in the above embodiment may not be particularly necessary. Also, for a certain period of time t, 1. ．． l may be set freely.

(2) In the above embodiments and other examples, the evaporator outlet temperature was used as the control variable to determine the optimal capacity, but it may also be the vehicle interior temperature, the refrigerant pressure in the evaporator, etc. Regarding the engine load, in addition to the amount of accelerator depression determined by a potentiometer, the rate of change in engine speed, manifold pressure, etc. may be used.

Furthermore, the linear graph shown in FIG. 4 may be controlled in a curved or stepwise manner without departing from the gist of the present invention.

Effects of the Invention As detailed above, in the cooling system according to the present invention, even if the engine load exceeds the reference value, the compressor capacity is minimized for a certain period of time, so that the compressor capacity is minimized for a certain period of time even when the engine load exceeds the reference value. During acceleration, the engine load can be sufficiently reduced without compromising the cooling feeling, improving acceleration performance, and after that, the compressor capacity can be adjusted between the optimum capacity and the minimum capacity as the temperature inside the vehicle begins to rise. Since the vehicle is parked between the two capacities, even when the engine load is high for a long period of time, such as when climbing a mountain, it has excellent effects such as improving the cooling feeling and reducing the engine load.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of the cooling circuit, Figure 2 is a flowchart showing a conventional control method, Figure 3 is a flowchart of an embodiment embodying the present invention, and Figure 4 is the relationship between temperature difference and capacity on the actual road side. 5 and 6 are graphs showing the relationship between operating time, capacity, and engine load in the example. 1-Cooling circuit 2-Variable capacity compressor 3-Condenser 6-Evaporator 8-Variable capacity mechanism 9-Control unit AIO-Temperature sensor 12-Temperature setting switch

Claims (1)

[Scope of Claims] 1) A capacity control method for a variable capacity compressor mounted on a vehicle and driven by engine output, in which the capacity of the compressor is controlled in accordance with a detected value of a control amount so as to always maintain an appropriate room temperature; When the detected value of the engine load exceeds a certain value, the compressor capacity is varied to the minimum value, and when the time in the minimum capacity state exceeds a certain period of time, the difference between the detected value of the control amount and the target value is determined, A capacity control method for a variable capacity compressor, the gist of which is adjusting the amount of decrease in compressor capacity according to this difference. 2) If the time in the minimum compressor capacity does not exceed a certain time and the engine load falls below a certain value,
Memorizing the operating time of the minimum compressor capacity;
A patent claim that, when the sum of the stored operating times exceeds a certain time, the difference between the detected value and the target value of the controlled variable is determined, and the amount of decrease in the compressor capacity is adjusted according to this difference. The method for controlling the capacity of a variable capacity compressor according to item 1.