JPH05213055A - Air conditioner for vehicle - Google Patents

Abstract

PURPOSE:To provide the stable control of an air conditioner, following the sudden fluctuation of a thermal load, but not the normal fluctuation of a thermal load. CONSTITUTION:This air conditioner is equipped with heat exchange output detector 12 for detecting the heat exchange output of a heat-exchanger circuit 1, and a capacity control device 11 for performing the feedback control of the capacity of a compressor 3 on the circuit 1 on the basis of a control operation, including a proportional operation for the variation of a deviation between the target value of heat exchange output and the detected value thereof. Furthermore, the capacity control device 11 is equipped with a gradient computation means 21 for computing a gradient due to the secular change of heat exchange output data, a gain characteristic memory section 22 for preliminarily setting and saving gain characteristic data proportionally changing for a change in the gradient, and a gain adjustment means 23 for adjusting the gain of the control operation on the basis of gain characteristic data corresponding to the computed gradient. According to this construction, detected data quickly converges to a target value, and becomes stable against the sudden fluctuation of a thermal load.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compressor capacity control device for an air conditioner for a vehicle which has a variable capacity compressor and exchanges heat with the compression and expansion of a refrigerant.

[0002]

2. Description of the Related Art Conventionally, in a vehicle air conditioner in which a heat load fluctuates a lot, in order to stably control the compressor capacity to a target performance, an operation amount with respect to a proportional value of a deviation between a target value and a detected value, A PI control method is adopted in which feedback control of the drive unit is performed based on the integrated value of the deviation in the state before each detection, or a PID control method in which the differential value of the deviation is also used. Has been done.

[0003]

However, in a vehicle air conditioner, a slight change in the temperature of the air flowing into the evaporator,
When the rotation speed of the evaporator blower is changed, or when the rotation speed of the evaporator blower is switched, or when the indoor air circulation is changed, the heat exchanging fan changes the rotation speed of the heat exchanger. It can be roughly divided into large heat load fluctuations such as when the outdoor air intake is switched, but if such a disturbance is fed back with a uniform coefficient, the movement related to the change amount of the deviation will be subtle. In some cases, excessive control is frequently performed with respect to thermal negative fluctuations, and stable control cannot be obtained, or conversely, quick response to large thermal load fluctuations may not be exhibited.

It is an object of the present invention to not follow the heat load fluctuations that normally occur very sensitively, and to quickly follow the rapid heat load fluctuations to obtain stable control. To provide an air conditioner for a vehicle.

[0005]

In order to solve the above-mentioned problems, the invention of claim 1 has a heat exchange circuit for exchanging heat with compression and expansion of a refrigerant, which has a variable capacity compressor. Based on a heat exchange output detector for detecting the temperature or pressure of the indoor heat exchanger of the heat exchange circuit, and at least a control operation including an operation for a proportional value of a deviation between the target value of the temperature or pressure and the detected value. In a vehicular air-conditioning system including a displacement control device that feedback-controls a compressor displacement according to an adjustment amount, the displacement control device includes a slope calculation unit that calculates a slope of a detected temperature or pressure with respect to a lapse of time. A gain characteristic storage unit that presets and stores gain characteristic data that changes in proportion to a change in gradient, and the gain characteristic data corresponding to the calculated gradient based on the gain characteristic data described above. And a gain adjustment means for adjusting the gain of the control operation. Further, the invention of claim 2 is characterized in that the above-mentioned gradient calculating means comprises means for calculating a mutual gradient of the average values of the respective detected data in different minute time zones before this time point. The invention according to claim 3 comprises the gradient calculating means according to claim 2, and the gain characteristic storage section has a minimum gain section in which a minimum gain is set for a small gradient of a predetermined value or less, and a minimum gain. It is characterized in that a gain characteristic in which a gradually increasing gain section in which the minimum gain is gradually increased to the maximum gain is set from the maximum gradient value in the section is stored.

[0006]

According to the first aspect of the present invention, the slope of the detected temperature or pressure over time is calculated by the slope calculating means, and the gain characteristic data corresponding to the calculated slope is adjusted from the gain characteristic storage section. Taken into the means,
The gain of the capacity control device is set based on the gain characteristic data. According to the second aspect of the present invention, the gradients of the average values of the respective detected data in the minute time zones different from each other before the time point are calculated by the gradient calculation means and used as the gradients at the time point. According to the third aspect of the present invention, the minimum gain is taken into the gain adjusting means from the gain characteristic storage unit for a small gradient less than or equal to a predetermined value due to the mutual gradients of the average values, and a large gradient greater than or equal to the predetermined value is obtained. In contrast, the maximum gain is similarly taken, and the incremental gain is gradually increased from the minimum gain to the maximum gain over the upper limit gradient value setting the minimum gain to the lower limit gradient value setting the maximum gain. Are also taken in.

[0007]

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

In the figure, reference numeral 1 denotes a heat exchange circuit for cooling the vehicle interior, which performs heat exchange with the compression and expansion of the refrigerant to air-condition the interior of the vehicle. Reference numeral 2 is an automobile engine, and 3 is a variable displacement compressor controlled by suction pressure. The compressor 3 is driven by being connected to the engine 2 by an electromagnetic clutch 4 to compress and circulate the refrigerant in the refrigerant circuit. This compressor capacity is controlled by a capacity control device 11 described later. Reference numeral 5 is an outdoor heat exchanger that receives and exchanges heat with the refrigerant compressed by the compressor 3, 6 is a blower for the heat exchange, 7 is an expansion valve for expanding the refrigerant that has passed through the outdoor heat exchanger 5, and 8 is an expansion valve 7 An indoor heat exchanger that receives the refrigerant that has passed through and exchanges heat, and 9 is a blower for the heat exchange. Each of the blowers 6 and 9 is a battery 10 that is a power source of the automobile.
Driven by. The indoor heat exchanger 8 is installed in a duct (not shown) communicating with the vehicle compartment and the outside air,
A damper can be used to appropriately switch the ratio between the circulation of indoor air and the intake of outdoor air.

A capacity controller 11 controls the capacity of the compressor 3 with reference to the temperature of the indoor heat exchanger 8. 12
Is a temperature detector as a heat exchange output detector, which detects the air temperature on the downstream side of the indoor heat exchanger 8 and detects the detected data VD.
Is output.

Reference numeral 13 denotes a target temperature setting circuit which outputs control target data VS on the basis of the temperature specification in the vehicle compartment. 1
Reference numeral 4 is a subtracter for subtracting the detected data VD from the control target data VS. The control target data VS and the detected data V
D is expressed using the same unit amount as each other.

Reference numeral 15 is a proportional arithmetic unit, which is a control target data VS.
And the deviation from the current detected data VDn for each sampling interval .DELTA.t, the operation amount for .DELTA.Vn = VS-VDn, and .DELTA.Vn are calculated. The sampling interval Δt is set to about 1 second, for example.

Reference numeral 16 denotes an integral calculator, which is an operation amount proportional to the integrated value of the deviation ΔVn, (ΣΔVi ΔT) / TI (where i =
0 to n) are calculated. Note that TI is a coefficient called an integration time for the operation, ΔT is an interval for performing control calculation,
The ΔT is equal to the sampling interval Δt.

Reference numeral 17 denotes a differential computing unit, which has a movement amount TD which is proportional to the changing speed of the deviation ΔVn of this time and the deviation ΔVn-1 of the previous time.
Calculate (Vn-Vn-1) / [Delta] T. TD is a coefficient called the differential time, which is related to the operation.

Reference numerals 18 and 19 are adders for adding the calculation result of the integral calculator 16 and the calculation result of the derivative calculator 17 to the calculation result of the proportional calculator 15, respectively.

Reference numeral 20 is an amplifier having a gain A, which amplifies the addition data and supplies it to the compressor 3. This amplification data
The data Mn can be expressed by the following equation.

Mn = A {ΔVn + (ΣΔViΔT) / TI + TD (V
n-Vn-1) /. DELTA.T} (where i = 0 to n) (1) The suction pressure of the compressor 3 is controlled by the amplification data Mn.

Reference numeral 21 is a gradient calculator, which expresses the gradient αn of the detected data VD with respect to the passage of time, αn = | {(VDn-3 + VDn-2) / 2- (VDn-1 + VDn)
/ 2} / (2Δt) | ... (2). The first term of the numerator of the formula (2) is the n
It is the average value of each detected data VD at the time points 2Δt and 3Δt before the time point, and the second term of the numerator is n time point and Δt.
This is the average value of each detected data VD at the time point before this. Then, the equation (2) is obtained by dividing the deviation of each of the average values by the time difference 2Δt between the respective average value calculation points, and represents the gradient between the respective average values as the gradient αn at the n point. Therefore, since the gradient α n represents the average of the gradient in the section of about several seconds, at least the disturbance of the high frequency of the cycle of several seconds or less is averaged, and the gradient α according to the equation (2) is calculated.
n is a value with high frequency reduced.

Reference numeral 22 denotes a gain characteristic storage unit which, according to the gain characteristic diagram shown in FIG.
Characteristic data is set and stored in advance. The gain characteristics include a minimum gain section in which the minimum gain As1 is set for a small gradient below the gradient αs1, a maximum gain section in which a maximum gain As2 is set for a large gradient above the gradient αs2, and a minimum gain section. From the upper limit gradient value αs1 in the gain section to the lower limit gradient value αs2 in the maximum gain section, a gradually increasing gain section in which the minimum gain As1 is gradually increased to the maximum gain As2 in proportion to the gradient αn is set. The above-mentioned minimum gain As1 is a value which is set so that the control output data Mn is hardly sensitive to the gradient .alpha.n according to the equation (2) which is generated by the normal minute heat load fluctuation. The maximum gain As2 is a value set so that the time until the vibration and stabilization of the detected data VD falls within the allowable value even if the gradient αn is a very large value.

Reference numeral 23 is a gain controller, which calculates the calculated gradient α
The gain A of the amplifier 20 is adjusted based on the gain characteristic data of the gain characteristic storage unit 22 in correspondence with n. That is, when αn <αs1, A = As1 ... (3a) When αs1 ≦ αn <αs2, A = {(As2-As1) /
(Αs2-αs1)} αn + (As1αs2-As2αs1) / (α
s2-αs1) (3b) When αn> αs2, the gain A is adjusted to A = As2 (3c). After that, the PID control by each of the elements 13 to 20 is executed by the expression (1) using each of the gains A. The first term in the equation (3b) represents the slope of the gain A with respect to the change of the slope αn,
The second term represents the intercept of the gain A axis.

Next, the operation of the vehicle air conditioner of FIG. 1 will be described. FIG. 3 is a flow chart showing the control operation, and FIG. 4 is an operation waveform diagram of each part.

When the operation is designated, n = 0 is set as the initial setting.
Next (S1), the blowers 6 and 9 are operated, the clutch 4 is operated, and the compressor 3 is connected to the engine 2 and operated (S2, S3). Refrigerant is compressor 3
Then, the outdoor heat exchanger 5, the expansion valve 7, and the indoor heat exchanger 8 are circulated to start cooling. In the temperature detector 12, the data VDn is sampled (S4), and if n ≧ 4 (S5), the gradient calculator 21 calculates the gradient αn using the equation (2) (S6). In the gain adjuster 23, the gain characteristic storage unit 2 is associated with the gradient αn.
The gain A of the amplifier 20 based on the gain characteristic data of 2
Is adjusted. That is, when αn <αs1 (S7),
The gain A = As1 shown in the equation (3a) is adjusted (S8),
When αs1 ≦ αn <αs2 (S7, S9), the gain A is adjusted to the equation (3b) (S10), and αn> α
When s2, the gain A = As2 shown in the equations (S9) and (3c)
(S11). Although the details are not shown in the flow chart, the PID control by the respective elements 13 to 20 is thereafter executed by the equation (1) using the respective gains A (S12). When the sampling time Δt elapses, n
Is incremented by 1 (S13, S14), and S4 to S14 are repeatedly executed. When n <4 at the beginning of activation (S
5), A = As2 is adjusted (S11).

With this control, the discharge capacity or suction pressure of the compressor 3 is controlled by the control output data Mn. FIG. 4 shows the rotation speed ω of the blower 9, the detection data VD of the temperature detector 12 and the control output data Mn. In section a, the rotation speed of the blower 9 after the apparatus is started. When ω is in a substantially stable operating state, αn <αs1 (S7), during which, the minimum gain A is stably adjusted to As1 (S8), and S4 to S14 are repeated, PID control is performed.

At the beginning of the section b, the detected data VD continues to decrease due to a sudden change in the rotation speed ω of the blower 9 or switching of the cooling conditions, and the gradient αn becomes equal to or greater than the set gradient αS1 ( S7), the gain A is S10 or S
The control output data Mn is rapidly set by the control signal 11 so that the detected data VD quickly converges to the control target data VS. However, in the calculation of the gradient .alpha.n in S6, since the gradients of the respective average values based on the average value of the respective detected data VD are used, the gradient .alpha.n becomes a value in which the high frequency component is reduced, The amplified data Mn does not unnecessarily fluctuate.

In FIG. 4, a waveform diagram by the conventional PID control in which the gain A is fixed to As1 is also shown by a broken line.
At the beginning of the section b, conventionally, the gain As1 is small with respect to a large heat load fluctuation, so the reaction is slow and the detected data VD deviates from the control target data VS, so that the control target data VS is changed. Although the convergence time also increases, in this embodiment, a smooth output characteristic can be obtained, and quick reactivity can be obtained even in the section b where a large heat load fluctuation is given.

[0025]

As described above, according to the first aspect of the present invention, the slope of the detected temperature or pressure with respect to the elapse of time is calculated, and the gain of the capacity control device with respect to the change of the calculated slope. Since it is set based on the gain characteristic data that changes proportionally, the detection data quickly converges to the target value and stabilizes. According to the second aspect of the present invention, since the mutual gradient of the average values of the respective detection data in each minute time period before this time point is calculated,
The influence of disturbance due to high frequency is reduced, and smooth feedback control becomes possible. According to the invention of claim 3, the gradient calculating means of claim 2 is provided, and the minimum gain is used for a small gradient equal to or less than a predetermined value, and the upper limit gradient value for which the minimum gain is set. From the minimum gain to the maximum gain over the predetermined gradient value for which the maximum gain is set, the gradually increasing gain is used in the same manner. Even if the load does not change so much and the heat load changes relatively, it quickly converges to the target value and stabilizes without changing significantly.

[Brief description of drawings]

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

FIG. 2 is a gain characteristic diagram related to storage in a gain characteristic storage unit.

FIG. 3 is a flow chart showing a control operation of the vehicle air conditioner of FIG.
Chart

4 is an operation waveform diagram of each part of the vehicle air conditioner of FIG.

[Explanation of symbols]

1 ... Heat exchange circuit, 2 ... Engine, 3 ... Compressor, 5
... outdoor heat exchanger, 6,9 ... blower, 7 ... expansion valve, 8 ... indoor heat exchanger, 10 ... battery, 11 ... capacity control device, 1
2 ... Temperature detector, 13 ... Target temperature setting circuit, 14 ... Subtractor, 15 ... Proportional calculator, 16 ... Integral calculator, 17 ... Differential calculator, 18, 19 ... Adder, 21 ... Gradient calculator, 22
... Gain characteristic storage unit, 23 ... Gain adjuster.

Claims (3)

[Claims] 1. A heat exchange circuit having a variable capacity compressor for exchanging heat with compression and expansion of a refrigerant, and heat exchange output detection for detecting temperature or pressure of an indoor heat exchanger of the heat exchange circuit. And a capacity control device for carrying out feedback control of the compressor capacity with an adjustment amount based on a control operation including at least the proportional value of the deviation between the target value of the temperature or pressure and the detected value thereof. In the air conditioner, the capacity control device presets and stores a slope calculating unit that calculates a slope of the detected temperature or pressure with respect to time, and gain characteristic data that changes in proportion to the change of the slope. And a gain adjusting means for adjusting the gain of the control operation based on the gain characteristic data corresponding to the calculated slope. Vehicle air-conditioning system to be. 2. The gradient calculating means comprises means for calculating a gradient between the average values of the respective detected data in different minute time zones different from each other before this point in time. Air conditioning system for vehicles. 3. The gain characteristic storage unit has a minimum gain section in which a minimum gain is set for a small gradient of a predetermined value or less, and a predetermined gradient in which a maximum gain is set from a maximum gradient value in the minimum gain section. 3. The vehicle air conditioner according to claim 2, wherein a gain characteristic in which a gradually increasing gain section in which the minimum gain is gradually increased to a maximum gain is set over a value is stored.