JPH03217320A - Control device for on-vehicle variable capacity compressor - Google Patents

Abstract

PURPOSE:To prevent excessive lowering of an engine speed and to improve a drive feeling by providing a capacity increase factor reducing means to reduce the capacity increasing speed of a variable capacity compressor when the rapid reducing state of the engine speed is detected. CONSTITUTION:An air conditioner 200 has a swing swash plate type variable capacity compressor 201 coupled to a crankshaft 113 of an engine 100 through an electromagnetic clutch 202. The capacity of the compressor is continuously changed by regulating a control pressure exerted on a capacity varying mechanism by means of an ECU 300. Capacity is controlled so that the fluctuation of a delivery amount of a compressor 210 due to a change in an engine speed determined from the engine speed detected by an engine speed detecting means 114 is compensated. In this case, in the ECU 300, a capacity increase factor reducing means to control so that a rapid reducing period and the increase speed of capacity area reduced when an engine speed rapid reduction state in which the reducing speed of the engine speed exceeds a reference level is detected is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a control device for a variable capacity compressor (hereinafter simply referred to as a compressor) used in an air conditioner driven by a vehicle engine.

[Prior Art] In a conventional vehicle engine-driven air conditioner, an on-vehicle variable capacity compressor control device adjusts the compressor in response to changes in the cooling load in order to obtain an appropriate cooling capacity in response to changes in the cooling load. By changing the capacity of the air conditioner, the discharge amount corresponds to the cooling load.

For example, as disclosed in Japanese Utility Model Publication No. 62-975, in the conventional vehicle-mounted variable displacement compressor control device, in view of the general rotational speed fluctuations of the vehicle engine that drives the compressor, changes in the engine rotational speed are The capacity is adjusted in reverse response to compensate for the discharge amount due to changes in engine speed, so that the discharge amount does not fluctuate regardless of changes in engine speed.

Therefore, the capacity is increased when the engine speed decreases.

Furthermore, the above publication also discloses reducing the capacity when the vehicle accelerates to reduce the load on the engine, and increasing the capacity when the vehicle decelerates to recover deceleration energy.

[Problem to be Solved by the Invention] However, when the engine speed suddenly decreases, for example, immediately after racing (i.e., engine revving), the control device of the variable displacement compressor does not maintain the discharge amount constant as described above. As a result, the load torque of the compressor increases rapidly, causing a sudden drop in engine rotation, and in the worst case, the engine stalls.

Such problems occurred not only during racing, but also when, for example, when braking suddenly or stopping acceleration suddenly.

The present invention has been made in view of the above-mentioned problems, and provides an on-vehicle variable displacement compressor control device that prevents an excessive drop in engine speed due to a sudden increase in compressor capacity in an operating region where engine speed suddenly drops. The problem to be solved is to do so.

[Means for solving the problems] Vehicle-mounted variable displacement compressor system I of the present invention! The I device includes a rotation speed detection means that detects the rotation speed of a vehicle engine and outputs an engine rotation speed signal, and detects a discharge amount fluctuation of the variable displacement compressor due to a change in the engine rotation speed based on the engine rotation speed signal. and capacity control means for controlling the capacity of the variable displacement compressor to compensate, the capacity control means detecting that the rate of decrease in engine rotational speed exceeds a reference level. The present invention is characterized by comprising: a rapid decrease in engine speed detection means; and a capacity increase rate reducing means for reducing the rate of increase in capacity during a period of rapid decrease in engine speed.

[Operation] When the rotational speed sudden decrease detection means detects that the rate of decrease in engine rotational speed exceeds a reference level, the capacity increase rate reduction means reduces the rate of capacity increase of the variable displacement compressor.

As a result, during the period of sudden engine speed decrease (and the period immediately following it), the capacity increase rate of the compressor to keep the discharge capacity constant is temporarily suppressed, and as a result, during this period of sudden engine speed decrease, This eliminates the rapid increase in engine load and the resulting sudden drop in engine speed.

[Example code] An embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows the entire system including the engine, air conditioner, etc. of a vehicle equipped with the on-vehicle variable displacement compressor control device of this embodiment.

First, the engine and air conditioner system will be explained.

A spark ignition water-cooled multi-cylinder engine 100 that generates vehicle running power includes an engine body 101 having an intake pipe 102 and an exhaust pipe 103.

The intake pipe 102 includes a throttle valve 104 that adjusts the amount of intake air.
The throttle valve 104 is provided with an idle switch 105 that detects the fully open state of the throttle valve 104.
is provided. In addition, a bypass passage 106 is provided in the intake pipe 102 to bypass the throttle valve 104, and the bypass passage 106 is used to adjust the passage area of the bypass passage 106 (adjust the flow rate of air passing through the bypass passage).
A bypass valve 107 of a near solenoid type is provided. This bypass valve 107 is the throttle valve 10
4. Engine rotation speed N when fully open (idle state)
E is adjusted to a predetermined value.

Further, a pressure sensor 108 that detects the intake pipe pressure downstream of the throttle valve 104 is provided in the intake pipe 102.
A fuel injection valve 109 is provided at each branch portion.

On the other hand, the engine body 101 is equipped with a spark plug 111 and a water temperature sensor 112 that detects the cooling water temperature, and the crankshaft 113 of the engine body 101 is equipped with a rotation angle sensor (the present invention) that detects the rotation angle of the crankshaft 113. A rotation speed detection means (referred to as rotation speed detection means) 114 is provided.

The air conditioner 200 that cools and dehumidifies the air inside the vehicle is equipped with a compressor 201 (for example, a swinging swash plate type variable capacity compressor) that can continuously change the stroke volume (piston stroke). It is connected to the crankshaft 113 of the engine 100 via an electromagnetic clutch 202 . The compressor 201 is equipped with a control valve (not shown) for variable capacity, and this control valve opens and closes according to the average value of pulse signals input from the ECU 300, which will be described later, to control the variable capacity mechanism of the compressor. The control pressure applied to the compressor is adjusted to continuously change the capacity of the compressor. The discharge port of the compressor 201 is connected to a condenser 204 via a high-pressure side refrigerant pipe 203a, and the condenser 204 sequentially connects a receiver 205 for refrigerant liquid storage, an expansion valve 206, an evaporator 208, and a low-pressure side refrigerant pipe 203b. It is connected to the suction port of the compressor 201 via. The opening degree of the expansion valve 206 is adjusted according to the temperature sensing tube 207 provided in the low pressure side refrigerant pipe 203b. The air conditioner 200, the compressor 201, and the control valve described above are already well known, so a detailed explanation will be omitted. Additionally, the air conditioner 200 is equipped with various sensors described below. First, compressor 20
1 includes a capacity sensor (capacity detection means in the present invention) that detects the capacity of the compressor (that is, the discharge amount per stroke).
212 is provided. For example, this capacitive sensor 21
2, various displacement sensors that detect the amount of displacement of the oscillating swash plate or the amount of displacement of the piston of the oscillating swash plate type variable capacity compressor can be used. Each refrigerant pipe 203 on the high pressure side and low pressure side
A and 203b are pressure sensors 21 for detecting refrigerant gas pressure.
0,211 are provided individually. Furthermore, an outlet temperature sensor 209 is provided at the outlet of the air conditioner 200 through which air cooled by the evaporator 208 is blown out into the vehicle.

The electronic control unit (ECU) 300 is a microcomputer device (detailed description of the internal configuration) that constitutes the target capacity value calculation means (including the rotation speed sudden decrease detection means and the capacity increase rate reduction means) and the capacity control means in the present invention. (omitted)].ECU
300 is an idle switch 105 and a pressure sensor 108
, water temperature sensor 112, rotation angle sensor 114, high pressure sensor 210, low pressure sensor 211, capacitance sensor 212
, an outlet temperature sensor 209, an air conditioner switch 213 for starting and stopping the air conditioner, and the like, and the engine 100 and the air conditioner 200 are controlled according to the input signals.

The capacity control subroutine of this variable displacement compressor control system will be explained with reference to the flowchart of FIG. 2 and the signal waveform diagram of FIG. 3.

Check whether the air conditioner switch 213 is turned on at 51000, and if it is not turned on, turn on the electromagnetic (Mq) clutch 20.
2 is turned off (S1022>Return to the main routine, and if it has been turned on, turn on the electromagnetic clutch 202 (S1022>Return to the main routine.
S1001) Start the compressor 201, and turn on the pressure sensor 210.
, 211 and the output signals of the capacity sensor 212, the compressor's high pressure (discharge side) Pd, low pressure (suction side) Ps,
Capacity VC is detected (S1002>).

Next, the low pressure Ps and its target value PS○ are compared (3
1003), if Ps>Pso, the current capacitance change △VC
is set to a predetermined amount α (S1005), and if PS<PS○, the current capacitance change amount ΔVC is set to a predetermined amount −α (51006),
If Ps=Pso, let the current capacitance change amount △Vc be O (
S1004).

That is, in S1003, the basic cooling load is detected using the low pressure ps, and in S31004 to S1006, feedback control is performed to make the capacity Vc follow this cooling load. Through this control, the low pressure PS is maintained at the level of the target value PSO (that is, the temperature of the evaporated H208 is kept constant).

Next, the engine speed NE is read from the rotation angle sensor 114 (S1100), and the amount of decrease ΔNE in the engine speed NE per unit period is calculated (S1'l01). Next, compare the reduction amount 8NE with the standard reduction amount 8NEO (31
007), if ΔNE>ΔNEO (that is, the engine speed NE is rapidly decreasing), it is checked whether the flag FSLOW is O (51008). This flag FSLOW
is called the capacity control slow mode flag,
Capacity change amount per unit time (in this case, capacity increase amount)
This is a flag that instructs execution of a control to reduce the capacity increase rate by reducing ΔvC (hereinafter referred to as capacity increase rate reduction control).

31008 checks whether the flag FSLOW is O, and if it is O (if the capacity increase speed reduction control is not commanded), the flag FSLOW is set to 1 (capacity increase speed reduction control is commanded), and the count value is set. CSLOW is reset to O (S1009), and the process advances to S1012. This count value CSLOW is the cumulative value of a slow mode execution counter that counts the time during which the capacity increase rate reduction control was executed, and the time until the count value CSLOW reaches β is the slow mode control execution period.

That is, in this embodiment, when the flag FSLOW is 1, an operation is performed to reduce the capacity increase speed in capacity control, and this capacity increase rate reduction control is performed based on the count value C.
This is executed during the time until SLOW reaches β (slow mode control execution period).

On the other hand, if FSLOW is 1 in S1008 (if the capacity increase speed reduction control is being executed), 1 is added to the count value CSLOW (time is advanced) in S1011.

Further, if ΔNE>ΔNEo is not established in S1007 (that is, the engine speed is not suddenly decreasing), it is checked whether the flag FSLOW is 1 (S1010). S
If the flag FSLOW is 1 at 1010 (a period in which the engine speed has suddenly decreased but the slow mode control execution period has not yet ended), the process advances to 31011, where 1 is added to the count value CSLOW (time )
The process advances to S1012. In addition, in S1010, if the flag FSLOW is O (a period in which the engine speed is not rapidly decreasing and is not in the slow mode control execution period), the process advances to 31019 and the capacity increase speed reduction control steps (81008 to 31017) are executed. take a detour.

In S1012, it is checked whether the count {direct CSLOW is smaller than β (that is, whether the slow mode control execution period has not expired). And count value C
If SLOW is less than β (unless it has expired), S
The amount of change in capacity per unit time (in this case, the amount of increase in capacity) Δ■C set in steps 1004 to S1006 is halved (S
1013), the capacity increase rate is reduced, and the process proceeds to S1014.

On the other hand, if the count value CSLOW is equal to or greater than β (if it has expired), the flag FSLOW is reset to O (the execution of the capacity reduction speed reduction control is ended, and the process proceeds to S1019).

In S1014, the engine speed NE is compared with a preset reference engine speed NEO, and if NE<N
If E○ (that is, if the engine speed NE is low), the capacity change amount (in this case, capacity increase) ΔvC, which was halved at Sl013, is further halved (S1015). In other words, the engine speed NE suddenly decreases. An excessively rapid decrease in engine speed due to a sudden increase in compressor capacity during
This becomes a problem in low rotational speed operating ranges where there is a risk of engine stalling.

Therefore, in these 31014 and 81015, the capacity increase speed is further reduced in the low engine rotational speed operating range to prevent overload when the engine rotational speed is low and the torque generated by the engine is small. .

Next, in S1016, the high pressure Pd, which is correlated with the load condition of the air conditioner, is compared with a preset reference pressure pdo, and if Pd>Pdo (that is, if the compressor load is higher than the reference level), ), the capacitance change amount (in this case, capacitance increase amount) ΔVc is further halved (S1017).

In this way, it is possible to eliminate the problem of increasing the capacity of the compressor operating under high load and further increasing the compressor driving power.

Next, in S1019, the capacity change amount ΔVc calculated in the above step is added to the current capacity value Vc, and a capacity control signal based on the new capacity value Vc after the addition is sent to the compressor (S
1020) The capacity of the compressor is variably reduced and the process returns to the main routine.

In the above flowchart, 31101 constitutes the rotation speed sudden decrease detection means according to the present invention, S1013 constitutes the capacity increase rate reducing means according to the present invention, and S1 1 01, 3
1013, S1019 constitutes the target capacity value calculation means in the present invention, and Sl020 constitutes the capacity control means in the present invention. Also, VC=(V
C+8■C〉 means the target capacitance value as used in the present invention.

The actual behavior will be explained using the time chart of FIG.

The behavior of the conventional compressor capacity control is shown by a dotted line, and the behavior of the compressor capacity control of this embodiment is shown by a solid line. In conventional control, when the engine speed decreases, the capacity change speeds 81 to a4 are all the same. The changing speeds K1 to K4 of the control of this embodiment are a1>K1, a2>K2, a3>K3, a4>K4, and Kt>K2, K3>K4.

In other words, if there is a difference in the load of the compressor, the larger the load, the slower the capacity change rate (capacity increase rate) (
Kl>K2>.

Also, if there is a difference in engine speed, the lower the engine speed, the
The capacity change rate (capacity increase rate) is slow (K3
>K4>.

As explained above, the on-vehicle variable displacement compressor control device of this embodiment prevents a sudden increase in engine load torque due to an increase in compressor capacity when the engine speed suddenly decelerates, and prevents problems such as a sudden drop in engine speed and engine stalling. I know what I can do.

Although the high pressure Pd was used as the compressor load detection means, the capacity Vc and the low pressure l. s, outside temperature, room temperature, blower air volume, or a combination thereof.

In addition, each capacity increase rate reduction period 11 to t4 in FIG.
is less than the maximum period β shown in FIG.

[Effects of the Invention] As explained above, the on-vehicle variable displacement compressor control device of the present invention is equipped with a capacity increase rate reducing means for reducing the capacity increase rate of the variable displacement compressor during a period when the engine speed suddenly decreases. It is possible to prevent the engine speed from decreasing excessively due to a sudden increase in the compressor capacity in an operating region where the engine speed rapidly decreases, thereby improving the driving sensation and preventing the occurrence of engine stalling.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the on-vehicle variable displacement compressor control device of the present invention, FIG. 2 is a flowchart showing its operation, and FIG. 3 shows the engine speed NE, compressor load, and capacity. FIG. 114...Rotational speed detection means 212...Capacity detection means 300...ECU (Target capacity value calculation means) (Capacity control means) (Rotation speed sudden decrease detection means) (Capacity increase rate reduction means)

Claims (1)

[Scope of Claims] A rotation speed detection means for detecting the rotation speed of a vehicle engine and outputting an engine rotation speed signal, and a discharge amount of the variable displacement compressor based on a change in engine rotation speed based on the engine rotation speed signal. and a capacity control means for controlling the capacity of the variable displacement compressor to compensate for fluctuations, wherein the capacity control means controls the rate at which the engine rotational speed decreases to exceed a reference level. An on-vehicle variable displacement compressor control device comprising: a sudden decrease in engine speed detection means for detecting a sudden decrease in engine speed; and a capacity increase rate reducing means for reducing the rate of increase in capacity during a period of sudden decrease in engine speed.