JPH03210082A - Control method for variable-capacity pump - Google Patents

Abstract

PURPOSE:To prevent the occurrence of a shock on an actuator by controlling the target discharge quantity according to the pump control pattern when a throttle is quickly operated, adding correction, and shifting to engine speed sensing control. CONSTITUTION:An arithmetic means 14 normally outputs the engine speed sensing (ESS) control signal is based on the difference between the target rotating speed Ne in response to an engine throttle action calculated by an arithmetic means 13 and the actual engine rotating speed Ns. When a detecting means 16 detects a quick throttle action, a selecting means 17 selects a pump control pattern based on the operation state immediately before the action, and an arithmetic means 18 outputs the pattern control signal is1 according to this control pattern. After the pattern control, a comparing/correcting means 20 adds correction and shifts to ESS control based on the pump control signal in the previous control cycle in response to the counting of a counter 19. The quick change of the pump discharge quantity and the occurrence of a shock can be prevented.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a variable displacement pump control method that uses a so-called engine speed sensing control method to control the discharge amount of the variable displacement pump according to the engine load condition. It is.

[Conventional technology]

The engine speed sensing (hereinafter referred to as ESS) control system reduces the pump discharge amount to reduce the total pump output when the engine speed decreases due to an increase in engine load, in order to effectively utilize engine horsepower and prevent engine stalling. This is a control method that prevents the consumed horsepower from exceeding the engine horsepower. Specifically, the target engine speed set by the engine throttle and the actual engine speed are compared, and if the difference becomes large, a pump control signal is output in the direction of decreasing the pump discharge amount. I have to.

However, this ESS control method had the following disadvantages.

In other words, when the engine throttle is suddenly operated (hereinafter referred to as "sudden throttle operation"), the difference between the target rotation speed and the actual rotation speed becomes large, just as when the load suddenly changes, so the driver is unable to understand the intention of increasing speed. Even though the throttle was operated at the same time, the pump discharge flow rate suddenly decreased at the time of the operation.

For this reason, there have been problems in that the actuator is suddenly decelerated immediately after the throttle is operated, giving a shock, and that operability is poor.

Therefore, in the past, Tokuko Sho 61-18028 and Sho 61-
As shown in Publications No. 31318, etc., when the difference between the target rotation speed and the actual rotation speed exceeds a certain value, this is determined to be a sudden throttle operation, and the ESS control is stopped for a certain period of time. A method has been proposed in which the pump discharge rate is maintained at the same discharge rate immediately before the change.

[Problem to be solved by the invention]

However, according to this method, the actual rotation speed may increase during the holding time and the difference from the target rotation speed may become zero or close to it.
When the control is restarted, the pump control coefficient is output as "1" or a value close to it depending on the load condition, so the pump discharge amount increases rapidly based on the increased engine speed.
This resulted in the actuator suddenly operating.

Therefore, the present invention provides a method for controlling a variable displacement pump that can prevent actuator shock due to sudden changes in pump discharge amount during such sudden throttle operation and improve operability.

[Means to solve the problem]

The present invention calculates the difference between the target rotational speed of the engine set by the engine throttle and the actual rotational speed, and performs engine speed sensing control to control the target discharge amount of the variable displacement pump according to this rotational speed difference. In a control method for a variable displacement pump, the amount of change in the target rotation speed of the engine is detected, and when the throttle is operated slowly so that the amount of change does not exceed a certain value, the engine speed sensing control is performed, and when the amount of change exceeds a certain value, the engine speed sensing control is performed. At the time of sudden operation, the control pattern for the subsequent target discharge amount is selected from among preset pump control patterns based on the operating state immediately before the change, and the target discharge amount is controlled according to the selected pump control pattern. After the control is performed, the engine speed sensing control is performed through a correction control that includes correction based on the pump control signal in the previous control cycle (claim 1).

Further, the invention of claim 2 provides that, as the operating state immediately before the change at the time of sudden throttle operation, one of the pump control signal and the actual rotational speed of the engine immediately before the change, and the load state of the actuator driven by the pump. It uses

[Effect]

According to this method, normal ESS control is executed at times other than when the throttle is suddenly operated, and when the throttle is suddenly operated, the pump is controlled according to a pump control pattern selected based on the operating state immediately before the throttle operation. Then, after this pattern control, by adding correction based on the pump control signal in the previous control cycle, it is possible to smoothly shift to the original engine speed sensing control.

Further, according to the invention of claim 2, in addition to the immediately preceding pump control signal or the actual rotational speed of the engine, the load state of the pump is also used as the operating state immediately before the change, so that more appropriate pattern control can be performed. I can do it.

〔Example〕

Embodiments of the present invention will be described with reference to the drawings.

In FIG. 1, 1 is an engine throttle, and the engine 2 is set by operating this engine throttle 1.
A signal of the target rotational speed Ne is input to the engine governor.

The target rotation speed Ne of the engine 2 is detected by the governor position detector 3.
Then, the actual engine rotation speed N+ is detected by the rotation speed detector 4, and these two rotation speed signals are sent to the controller 5.
is input.

This controller 5 includes an analog input section (A/D converter) 6, a digital input section 7, and a central processing unit (CPU).
8. A storage device 9 consisting of a ROM and a RAM, and a regulator drive section 12 that outputs a pump control signal (tilting command current) t to a regulator 11 of a variable displacement pump (hereinafter simply referred to as pump) 10. There is.

The storage device 9 stores functions for ESS control, various pattern functions for pattern control, etc., and these stored values are read out to the CPU 8 at appropriate times, and various data are written to the storage device 9.

The internal configuration of the CPU will be explained with reference to FIG.

Reference numeral 13 denotes a rotational speed difference calculation means for calculating the difference ΔN between the target rotational speed Ne and the actual rotational speed Ns, and 14 denotes an ESS signal calculation means for calculating an ESS control signal in accordance with this rotational speed difference ΔN. In this ESS control signal calculation means 14, when the rotational speed difference ΔN does not exceed a certain value, the coefficient is set to 1, and when it exceeds, the smaller the control coefficient K is determined as the rotational speed difference ΔN increases, and the pump control signal js is determined based on this. The signal is outputted to the output means 15 for the regulator drive section 12 in FIG.

That is, the ES reads fluctuations in engine load from changes in the rotational speed difference ΔN and reduces the discharge amount of the pump 10 when the load becomes large (when the rotational speed difference ΔN becomes large).
S control is performed.

The controller 8 also includes a sudden throttle detection means 16.
is provided. This sudden throttle detection means 16 is
Target rotational speed N detected by governor position detector 3 in Fig. 1
The amount of change ΔNe of e per unit time is detected, and if this exceeds a certain value, it is determined that the throttle operation is sudden.

This sudden throttle operation signal is sent to the pattern selection means 17, where a subsequent control pattern is stored in advance in the storage device 9 of FIG. 1 based on the pump control signal as the operating state immediately before the sudden throttle operation. The control pattern is selected from among various control patterns.

Note that the control pattern stored in the storage device 9 is obtained as follows.

■ Measurement of settling current By measuring the settling current (at steady state) under various load conditions, the target range of the control pattern after sudden throttle operation is determined.

■ Temporary determination of control pattern A control pattern is tentatively determined based on the result of (2) above.

■ Actual machine confirmation test Change the load by operating the actual machine and confirm that there is no shock. If there is a shock, make some changes to the control pattern and perform the confirmation test again.

■ Determining the control pattern If the shock disappears in step (2) above, determine the control pattern.

Further, in FIG. 2, 18 is a pattern control signal calculation means for calculating the pattern control signal tS1 based on the selected control pattern, 19 is a counter that performs a time measurement operation at the start of pattern control, and the time measurement period by this counter 19 is Within this, pattern control and correction control by the comparison/correction means 20 are performed continuously.

Next, the pump control action by this method is shown in the flowchart in Figure 3, Figures 4 (A) to (D), and Figures 5 (A) and (B).
This will be explained using the graph below.

At the start of the control, various data such as the target rotation speed Ne and the actual rotation speed N+ are read (step S1), and then the second
Based on the rotation speed difference ΔN obtained by the rotation speed difference calculation means 13 shown in the figure, the ESS control signal calculation means 14
An SS control signal ts is calculated (step S2).

Thereafter, it is determined by the sudden throttle detection means 16 in FIG. 2 whether or not a sudden throttle operation has been performed (step S3).
, if the throttle operation is not sudden, the ESS control is executed as usual (step S4, step S5).
).

On the other hand, if it is determined in step S3 that it is a sudden throttle operation (A1 in the fourth diagram indicates the point of sudden throttle operation), a flag is set (step Ss). Based on this, the pattern selection means 17 shown in FIG. 2 selects a subsequent control pattern (step S7).

Pattern control is started from here, and after it is confirmed that the sudden throttle operation flag has been set (step S4), the function of the control pattern selected by the pattern selection means 17 is used to create the pattern shown in FIG. A pump control signal (hereinafter referred to as a pattern control signal) tsl is calculated by the control signal calculating means 18 (step Ss).

At this time, the counter 19 starts timing operation (step S9), and the count value t is smaller than the predetermined constant t1 [t in FIG. 4(c)].
. In the pattern control period C-t), the pattern control signal jsl is output as the pump control signal t (step S40, step S□,).

In this way, within a certain period from the sudden throttle operation, the ES
By performing pattern control instead of S control, ES
It is possible to prevent sudden changes in the pump discharge amount, which is a disadvantage of S control, and to control the pump discharge amount without causing shock to the actuator.

Then, when this pattern control period C elapses (No in step S10), thereafter, step S12
YES period, that is, t1 in FIG. 4 (c)
During the correction control period C2 from ~t2, the following correction control is performed.

First, a certain width (offset value) is applied to the ESS control signal 7s.
The numerical value with ±α is compared with the pump control signal tS2 in the previous control cycle.Step S13, Step 5
14), case of tS2≧, 4s+α (step S 1
3), the value of js2-δ is obtained by subtracting the correction value δ from tS2, and in the case of tS2≦7s-α (in the case of No in step S), the value of js2-δ is calculated by subtracting the correction value δ from tS2. The added values of js20δ are each output (Step S5. Step 816).

On the other hand, in the case of ts2>jS−α (Y
In the case of ES), the flag is reset to indicate that the correction has ended (step 517), and the ESS control signal S is output as the pump control signal t. Further, when the count value t exceeds the constant t2 (No in step S12), the flag is reset in the same manner as described above (step 819), and then the ESS control signal tS is output as the pump control signal t.

Furthermore, this pump control signal t is written into the storage device 9 of FIG. 1 as the previous control signal 7s2.

In this way, when making a transition from pattern control to the original ESS control, by making corrections that gradually bring the pump control signal t closer to the ESS control signal ts, the transition can be made smoothly and sudden changes in pump discharge amount at the time of transition can be avoided. can be prevented.

The trend of the pump control signal shown in FIG. 4(c) is shown in more detail in FIG.

Figure 5 (a) shows the case where the throttle is suddenly operated in the direction of speed increase from a state where the pump discharge amount is large, and Figure 5 (b) shows the case where the throttle is suddenly operated in the direction of speed increase from a state where the pump discharge amount is small. are shown respectively.

According to ESS control, as shown by the dashed line in both figures, the pump discharge amount suddenly decreases from the sudden throttle operation point A1, and then gradually increases as the actual engine speed approaches the target rotation speed. become.

On the other hand, according to this method, the pump discharge amount gradually increases during the pattern control period from point A1 to point A2, and
During the correction control period up to three points, the values approach the ESS control value, and when they almost overlap, the transition to ESS control is made.

With the above control, it is possible to prevent sudden changes in the pump discharge amount due to sudden throttle operation, and to smoothly change the pump discharge amount in accordance with changes in the actual rotational speed of the engine. Therefore, the actuator speed can be changed smoothly as shown in FIG. 4(d).

Incidentally, in the above embodiment, the immediately preceding pump control signal 7s is used as the operating state immediately before the sudden throttle operation as an element (variable) for selecting the control pattern, but the immediately preceding actual engine rotation speed is used. Even in this case, the same effects as in the above embodiment can be obtained.

Alternatively, in addition to these, a load detector 21 detects the load state of the actuator as shown by the broken line in FIG.
may be provided, and this actuator load state may also be used as an element for control pattern selection. In this way, as shown in Fig. 6, the control pattern can be changed according to the load condition of the actuator, which prevents sudden changes in the pump discharge amount and provides more efficient control of the engine horsepower. be able to.

〔Effect of the invention〕

As described above, according to the present invention, the amount of change in the target rotational speed of the engine is detected based on the engine speed sensing control method, and when the amount of change exceeds a certain value and the throttle is suddenly operated, the operating state immediately before the change is restored. Based on this, a subsequent control pattern for the target discharge amount is selected from among preset pump control patterns, and after controlling the target discharge amount according to the selected pump control pattern, correction is made to this pattern control to control the engine. By shifting to speed sensing control, it is possible to prevent sudden changes in the pump discharge amount and the occurrence of shocks in the actuator immediately after a sudden throttle operation or when shifting to engine speed sensing control, which is the case in the past. Operability can be improved.

Further, according to the invention of claim 2, since the load state of the actuator driven by the pump is used in addition to the immediately previous pump control signal or the actual rotational speed of the engine as the operating state immediately before the change, pattern control can be performed accurately. This increases the accuracy and allows for more appropriate control.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a device for implementing a control method according to an embodiment of the present invention, and FIG.
FIG. 3 is a block diagram showing the internal configuration of the PU, FIG. 3 is a flowchart for explaining the operation of the method, and FIG.
A) shows how the engine's target rotational speed changes after a sudden throttle operation, (b) shows how the actual engine speed changes, (c) shows how the pump control signal changes, and (d) are diagrams showing the changes in the actuator speed, respectively.
Figures 5(A) and 5(B) are diagrams showing the changes in Figure 4(C) in more detail, and Figure 6 is Figure 4(C) when the load condition of the actuator is also used as an element for pattern selection. This is a corresponding diagram. 1...Engine throttle, 2...Engine, 3.
... An engine governor position detector as a target rotation speed detection means, 4... A rotation speed detector as an actual rotation speed detection means, 5. A controller, 8. A CPU of the controller, 9.・Storage device, 13... Rotation speed difference calculation means in CPU, 14... Control signal calculation means for engine speed sensing control, 16... Sudden throttle detection means, 17... Pattern selection means , 18・
...Control signal calculation means for pattern control, 19...
・Counter, 0... Comparison/correction means for correction control.

Claims (1)

[Claims] 1. An engine speed that calculates the difference between the target engine speed set by the engine throttle and the actual engine speed, and controls the target discharge amount of the variable displacement pump according to this speed difference. In a variable displacement pump control method that performs sensing control, the amount of change in the target rotational speed of the engine is detected, and when the amount of change does not exceed a certain value and the throttle is operated slowly, the engine speed sensing control is performed to keep the amount of change constant. When suddenly operating the throttle exceeding the value,
Based on the operating state immediately before the change, a subsequent control pattern for the target discharge amount was selected from among preset pump control patterns, and pattern control was performed to control the target discharge amount according to the selected pump control pattern. rear,
A method for controlling a variable displacement pump, characterized in that the process shifts to the engine speed sensing control after correction control that includes correction based on the pump control signal in the previous control cycle. 2. As the operating state immediately before the change when the throttle is suddenly operated, one of the pump control signal immediately before the change, the actual rotational speed of the engine, and the load state of the actuator driven by the pump is used. A method for controlling a variable displacement pump according to claim 1.