JPH076503B2 - Variable capacity compressor control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention converts the rotary motion of a rotary drive plate whose tilt angle is variable to a reciprocating linear motion of a piston through a swing swash plate, and also drives the rotary drive. The present invention relates to a control method for a variable displacement compressor that controls the compression capacity by changing the inclination angle of the swing swash plate by the pressure difference between the suction pressure and the pressure in the crank chamber that houses the plate and the swing swash plate. is there.

(Prior Art) In this type of compressor, a passage that connects the crank chamber and the discharge chamber is provided, and an electromagnetic control valve mechanism is provided on this passage to connect the discharge chamber and the suction chamber to a refrigerant gas circulation circuit. The duty ratio of the opening / closing operation of the electromagnetic control valve mechanism is controlled based on information such as the temperature of the air blown from the evaporator, the voltage for controlling the air flow in the blower that controls the amount of air blown from the evaporator, and the number of revolutions of the compressor. Therefore, a method of controlling the pressure in the crank chamber is generally adopted, and the compression capacity control is performed by such pressure control in the crank chamber. The duty ratio is calculated by calculation based on the proportional-integral-derivative control formula in the control computer, and feedback control is performed according to the variation of the duty ratio of the calculation result. In the proportional-plus-integral-derivative control, a steady position deviation (offset) that does not match the target value occurs when the control is performed only by the proportional action, but the offset can be removed by adding the integral action. If the derivative action is added to the proportional-integral control capable of removing the offset, the quick response to the change of the control system is increased, and the control performance is further improved as compared with the proportional-integral control.

(Problems to be solved by the invention) However, if the integral operation is excessively strengthened, the control stability performance is deteriorated, and if it is weakened, the quick response performance is deteriorated. There are inherent inhibiting factors that conflict with each other in achieving quick response performance and stability performance, such as sensitively reacting to noise disturbance and deteriorating the control process. Therefore, it is necessary to set each control coefficient in proportional operation, integral operation, and derivative operation in consideration of this situation, but it is also suitable for a sudden change in the set blowing air temperature or the setting blowing air flow rate due to an artificial operation. It is unreasonable to obtain a large duty ratio variation, that is, to set a control coefficient that may include a relatively large variation of the duty ratio in a short period. Therefore, when a sudden change in the set blown air flow rate occurs, the temperature change in the vehicle compartment becomes large, and there is the inconvenience that sufficient responsiveness cannot be obtained for switching the set blown air temperature.

(Means for Solving the Problems) Therefore, in the present invention, the rotary motion of the rotary drive plate whose tilt angle is variable is converted into the reciprocating linear motion of the piston through the swing swash plate, and the pressure in the crank chamber and the suction pressure are changed. Control the compression capacity by changing the tilt angle of the swash plate by the differential pressure via the piston and control by opening and closing the electromagnetic control valve mechanism interposed on the pressure control passage that connects the discharge chamber and the crank chamber. Targeting a swing swash plate compressor that controls the tilt angle of the swing swash plate by the differential pressure between the pressure in the crank chamber and the suction pressure through the piston, at least the arithmetic control function of proportional operation control and integral operation control A control computer provided with calculates and outputs a duty ratio control amount for the electromagnetic control valve mechanism, and sets an air volume from an evaporator interposed on a refrigerant gas circulation circuit connecting the discharge chamber and the suction chamber. At the time of switching setting of the air volume setting means or at the switching setting of the blowing air temperature setting means for setting the temperature of the air blown from the evaporator, the switching compensation amount is added to the duty ratio control amount in conjunction with these switching settings.

(Operation) That is, in a normal state, the control computer calculates the proportional-integral control formula or the proportional-integral-derivative control formula based on information such as the blown air temperature, the compressor rotation speed, the outside air temperature, and the blown air flow rate. The resulting duty ratio is output to the electromagnetic control valve mechanism. If the set blown air temperature or set blown air flow rate is switched and set,
Only when this switching is set, the control computer calculates the control formula in which the switching compensation value is added to the proportional-plus-integral control formula or the proportional-plus-integral-derivative control formula, and outputs the calculated duty ratio to the electromagnetic control valve mechanism. As a result, the switching compensation value works effectively even for a sudden change in the set outlet air temperature or the set outlet air flow rate that cannot be covered by the proportional integral control or the proportional integral derivative control, thereby improving the stability and quick response of the control system. Both can achieve satisfactory duty ratio control.

(Example) Hereinafter, one example which materialized the present invention is described based on a drawing.

A front housing 2 and a rear housing 3 are joined and fixed to the front and rear of a cylinder block 1 which is a part of the housing of the entire compressor, and a rotary shaft 4 is rotatably supported by the cylinder block 1 and the front housing 2. There is. In the front housing 2, a rotary support 5 is fixed to the rotary shaft 4, and a support arm 6 is provided on the rear surface side.
And a long hole at the tip of the support arm 6.
6a is transparently installed. A pin 7 is slidably fitted in the long hole 6a, and a rotary drive plate 8 is connected to and supported by the pin 7 with a variable tilt angle.

A sleeve 9 is slidably supported by the rotary shaft 4 on the rear side of the rotary support body 5, and is pressed and biased toward the rotary support body 5 side by a pressing spring 10 so that the sleeve 9 projects to the left and right sides of the sleeve 9. The shaft pin 9a (only one of which is shown) provided is engaged with an engagement hole (not shown) of the rotary drive plate 8. As a result, the rotary drive plate 8 can swing in the direction of the rotary shaft 4 about the shaft pin 9a. A swing swash plate 11 is supported on the rear surface side of the rotary drive plate 8 so as to be relatively rotatable, and a crank chamber 2a in the front housing 2, a suction chamber 3a and a discharge chamber in the rear housing 3 are provided.
A piston 13 in a cylinder bore 12 penetrating the cylinder block 1 so as to connect the 3b to each other and a swing swash plate 11 are connected by a piston rod 14. Therefore, the rotary motion of the rotary shaft 4 is converted into the forward and backward reciprocating swing of the swing swash plate 11 via the rotary drive plate 8, and the piston 13 moves back and forth in the cylinder bore 12. As a result, the refrigerant gas sucked from the suction chamber 3a into the cylinder bore 12 is discharged to the discharge chamber 3b while being compressed, but the piston 13 having the pressure in the crank chamber 2a and the suction pressure is
The stroke of the piston 13 changes according to the differential pressure via the, and the tilt angle of the swing swash plate 11 that affects the compression capacity changes.

At the bottom of the cylinder block 1, the pressure relief passage 1a is provided in the crank chamber.
2a and the suction chamber 3a are provided so as to communicate with each other, and an increase in pressure in the crank chamber 2a is suppressed.

An electromagnetic control valve mechanism 15 is provided in the rear end protrusion of the rear housing 3.
The valve element 18 that is adsorbed against the pressure spring 17 by the excitation of the electromagnetic coil 16 is always attached to the upper opening of the valve hole 19a formed in the valve seat 19 by the pressing action of the pressure spring 17. It is blocked. The discharge chamber 3b is connected to the upper opening of the valve hole 19a via a passage 20, and the crank chamber 2a is connected to the lower opening of the valve hole 19a via a passage 21,
When the electromagnetic coil 16 is excited, the discharge chamber 3b and the crank chamber 2a communicate with each other via a pressure control passage including the passage 20, the valve hole 19a, and the passage 21.

A condenser, an expansion valve 24, and an evaporator 25 are sequentially interposed on a refrigerant gas circulation circuit 22 that externally connects the suction chamber 3a and the discharge chamber 3b, and the expansion valve 24 is installed on the discharge side of the evaporator 2. The opening amount is controlled based on the pressure and temperature of the refrigerant gas detected by the temperature-sensitive cylinder 26. The air volume control voltage of the blower 27 that blows out the air cooled by the evaporator 25 is switched and set by the switching operation of the air volume adjustment lever 28 in the vehicle interior,
This switching setting changes the flow rate of air blown into the vehicle compartment from the outlet of the evaporator 25.

The electromagnetic control valve mechanism 15 is controlled to open and close based on the command voltage signal V (t) output from the control computer C, and the control computer C detects the detection voltage from the blower voltage detector 30 that detects the air volume adjustment voltage of the blower 27. , A temperature detector 31 for detecting the blowout temperature from the evaporator 25, a rotation speed detected by the compressor rotation speed detector 32 for detecting the rotation speed of the rotary shaft 4 of the compressor, and an outside air temperature detected by the outside air temperature detector 33. Based on the above, the command voltage signal V is set with the blowing temperature Tx (t) set by the operation of the room temperature adjusting lever 29 in the passenger compartment as a target value.
(T) is calculated and output. This command voltage signal V (t) is superimposed and compared with the triangular wave signal S output from the triangular wave oscillator 34 in the comparator 35, and the triangular wave signal S and the command voltage signal V (t) are superimposed as shown in FIG. The control voltage signal U (t) of the square column corresponding to the alignment area is output from the comparator 35 to the drive circuit 36. As a result, the opening / closing control of the electromagnetic control valve mechanism 15 is performed in accordance with the duty ratio of the control voltage signal U (t) of the square column. If the duty ratio is increased, the crank chamber is increased.
The pressure in 2a rises, and if the duty ratio is lowered, the pressure in crank chamber 2a falls.

The following proportional-plus-integral-derivative control formula is used in the calculation of the command voltage signal V (t) executed by using the detected voltage, the detected blowout temperature, the detected rotational speed, and the detected outside air temperature as control inputs.

V (t) = Kp ・ E (t) + Ki ・ ∫E (t) dt + Kd ・ d / dt * E (t) ・ ・ ・ (1) However, d / dt ＊ represents the differential operator, E (T) is the difference between the set outlet temperature Tx (t) and the detected outlet temperature T (t),
Kp, Kr, and Kd are control coefficients determined based on the set outlet temperature Tx (t), the detected outlet temperature T (t), the detected blower voltage, the detected compressor rotation speed, and the detected outside air temperature.

In addition to the basic proportional-integral-derivative control formula represented by formula (1), the control computer C has the following arithmetic control formula (2),
It has an arithmetic control function based on (3) and (4).

V (t) = Kp ・ E (t) + Ki ・ ∫E (t) dt + Kd ・ d / dt * E (t) + k ・ At ・ ・ ・
(2) V (t) = Kp ・ E (t) + Ki ・ ∫E (t) dt + Kd ・ d / dt * E (t) + ΔT ・ Bt ・ ・ ・
(3) V (t) = Kp ・ E (t) + Ki ・ ∫E (t) dt + Kd ・ d / dt * E (t) + k ・ At + ΔT ・ Bt
(4) However, k represents the number of switching steps of the air volume adjusting lever 28, and ΔT represents the switching temperature difference of the set blowout temperature Tx (t). The constants A and B are set to have the following relationship.

0 <| A | 0 <| B | The formula (2) is used only during a predetermined time in conjunction with the switching setting of the set voltage performed by the operation of the air volume adjusting lever 28, and the formula (3) is the room temperature adjusting lever. It is used only for a predetermined time in conjunction with the switching setting of the blowing temperature T (t) performed by the operation of 29. In addition, formula (4) is the air volume adjustment lever 28
It is used when the room temperature adjusting lever 29 is operated almost at the same time.

FIG. 2 shows a flow chart for controlling the opening and closing of the electromagnetic control valve mechanism 15, and the control method of the variable displacement compressor will be described below based on this flow chart.

The control computer C arranges the air volume adjusting lever 28 and the room temperature adjusting lever 29 at the positions shown by the solid lines in FIG. 1 and sets the blower voltage and the blowout temperature Tx (t), the detected blowout temperature T (t), the detected blower. The calculation of the calculation control formula (1) is performed based on the voltage, the detected compressor rotation speed, and the detected outside air temperature, and the calculated command voltage signal V (t) is output to the comparator 35. The comparator 35 superimposes and compares the compression capacity command voltage signal V (t) and the triangular wave signal S, and outputs the compression capacity control voltage signal U (t) of the square column corresponding to the superposition area at a predetermined short time interval. It outputs to the drive circuit 36 every Δt. Duty ratio of the compression capacity control voltage signal U (t) corresponds to the level T ₁ of the area of the level M and the set outlet temperature curve C3 setting blower voltage curve C2 of the curve C1 shown in FIG. 4, the electromagnetic control valve mechanism Open / close control of 15 is performed with this duty ratio.

When the air flow rate adjusting lever 28 is switched in two steps from the level M to the level L at time t _{1 as} shown by the set blower voltage curve C2, the switching blowout flow rate, that is, the input signal of the set blower voltage is input. In response, the control computer C performs the calculation of the calculation control formula (2) and outputs the command voltage signal calculated by the calculation control formula (2) at each short time interval Δt to the comparator 35 for a predetermined time. That is, the command voltage signal V (t) fluctuates with the amount of change represented by the following equation (5) at each short time interval Δt.

ΔV (t) = δ (t) + 2A (5) where δ (t) = Kp {T (t-Δt) -T (t)} + Kr {Tx (t) -T (t)} + Kd {2T (t-Δt) -T (t-2Δt) -T (t)} The variable element δ (t) in equation (5) is the variable amount based on the proportional-integral-derivative control, and the variable element 2A is This is the amount that compensates the blower voltage that cannot be covered only by the variation amount δ (t), that is, the quick response to the switching setting of the blowoff flow rate. By adding the switching compensation amount 2A to the normal fluctuation amount δ (t), the fluctuation of the command voltage signal V (t) is delayed even when the set blowing flow rate is rapidly changed by the operation of the air volume adjusting lever 28. Follow without. As a result, the duty ratio of the compression capacity control voltage signal U (t) in the rectangular array increases rapidly at time t _{1 as} shown by the curve C 1 in FIG. Does not significantly change from the set outlet temperature T ₁ after the time t _{1 as} shown by the curve C4.

The calculation using the equation (2) is performed for the predetermined time, and the equation (1) is used again after the predetermined time has elapsed. In addition,
Curves C'1 and C'4 indicated by chain lines in FIG. 4 show the fluctuations of the duty ratio and the blowing temperature only by the conventional proportional-integral-derivative control, and the fluctuations of the duty ratio due to the switching of the air volume adjusting lever 28 at time t ₁ and The difference in variation of the blowout temperature is clear.

When the room temperature adjusting lever 29 is switched from the level T ₁ to, for example, the level T ₂ at the time t _{2 as} shown by the set outlet temperature curve C3, the control computer responds to the input signal of the outlet temperature set for the switching. C performs the calculation of the calculation control formula (3), and outputs the command voltage signal V (t), which fluctuates by the change amount shown in the following formula (6), to the comparator 35 for a predetermined time.

ΔV (t) = δ (t) + (T ₁ −T ₂ ) B (6) The variation factor B (t) is a speed for the blowout temperature switching setting that cannot be covered only by the variation amount δ (t). This is the amount that compensates for the responsiveness, and as a result, the duty ratio decreases rapidly at time t _{2 as} shown by the curve C1, and due to this rapid change in the duty ratio, the actual blow-out temperature at time t ₂ as shown by the curve C4. After ₂ the set blowing temperature T ₁ rapidly changes to the new setting blowing temperature T ₂ . Then, when the predetermined time has elapsed, the command voltage signal V (t) is calculated using the equation (1).

When the air volume adjusting lever 28 and the room temperature adjusting lever 29 are switched within the predetermined time, the command voltage signal V (t) is calculated using the equation (4).

The present invention is, of course, not limited to the above-mentioned embodiment, and for example, the switching compensation amount is set as a function of the time variable, or the air volume adjusting lever 28 or the room temperature adjusting lever.
Proportional-integral control may be adopted as the basic control used other than the time of switching 29. The comparative integral control is inferior in the quick response to the comparative integral differential control, but in the control other than the switching of the air volume adjusting lever 28 or the room temperature adjusting lever 29, the proportional integral control does not cause any inconvenience in the quick response. It is also possible to employ comparative integration control as the basic control.

Effect of the Invention As described above in detail, according to the present invention, when the air volume setting means is set to be switched or the blown air temperature setting means is set to be switched, the duty ratio control amount is changed over time in accordance with the change compensation amount. Therefore, even when a large change occurs in the switching setting of the blowout temperature or the blowout flow rate, the switching compensation amount plays a large role as a rapid variable element of the duty ratio control amount, and the actual blowout temperature is It has an excellent effect that it can accurately follow the set blowing temperature.

[Brief description of drawings]

FIG. 1 is a combination diagram of a longitudinal section and a block circuit of a compressor showing an embodiment embodying the present invention, FIG. 2 is a flow chart, and FIG. 3 is a superposition comparison of a compression capacity command voltage signal and a reference triangular wave. FIG. 4 is a graph showing the compression capacity control voltage signal obtained by the above, and FIG. 4 is a graph showing each curve of the set blower voltage, the set blowout temperature, the duty ratio, and the actual blowout temperature. Cylinder block 1 constituting the housing, similarly front housing 2 and rear housing 3, crank chamber 2
a, suction chamber 3a, discharge chamber 3b, rotary shaft 4, rotary drive plate 8, swing swash plate 11, cylinder bore 12, piston 13, piston rod 14, electromagnetic control valve mechanism 15, valve hole constituting pressure control passage.
19a and passages 20, 21, refrigerant gas circulation circuit 22, air volume adjusting lever 28 as air volume setting means, room temperature adjusting lever 29 as blowout temperature setting means, control computer C, command voltage signal V (t as duty ratio control amount ), The temporal change amount ΔV (t) of the duty ratio control amount, and the switching compensation amounts A and B.

Claims (1)

[Claims] 1. A crank support, a suction chamber, a discharge chamber, and a cylinder bore connecting these chambers are defined and formed, and a rotary support on a rotary shaft in a housing for accommodating a piston in the cylinder bore so that the piston can reciprocate linearly. A rotary drive plate is supported by a variable tilt angle, and is rotated via a swing swash plate supported on the rotary drive plate so as to be relatively rotatable, and a piston rod interposed between the swing swash plate and a piston. The rotary motion of the drive plate is converted into the reciprocating linear motion of the piston, and the pressure and suction pressure in the crank chamber controlled by the opening and closing of the electromagnetic control valve mechanism interposed in the pressure control passage that connects the discharge chamber and the crank chamber. In a variable displacement compressor that controls the tilt angle of the swash plate by the differential pressure via a piston of the control valve and a control computer that has at least a calculation control function for proportional operation control and integral operation control. At the time of switching setting of the air volume setting means for calculating and outputting the duty ratio control amount for the solenoid valve control mechanism to set the air volume from the evaporator interposed on the refrigerant gas circulation circuit connecting the discharge chamber and the suction chamber. A control method for a variable displacement compressor, wherein a switching compensation amount is added to the duty ratio control amount at the time of switching setting of a blowing temperature setting means for setting a blowing temperature from an evaporator.