JP2539935B2 - Control method for variable displacement pump - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a variable displacement pump control method that employs a so-called engine speed sensing control method that controls the discharge amount of a variable displacement pump according to the load state of an engine. It is a thing.

[Conventional technology]

The engine speed sensing (hereinafter referred to as ESS) control method reduces the pump discharge rate to effectively utilize engine horsepower and prevent engine stall when the engine speed decreases due to an increase in engine load. It is a control method that prevents the consumed horsepower from exceeding the engine horsepower.

Specifically, the target engine speed set by the engine throttle is compared with the actual engine speed, and if the difference becomes large, it is considered that the engine load has increased and the pump discharge rate decreases. The pump control signal of is output.

However, this ESS control system has the following problems.

That is, when the engine throttle is suddenly operated (hereinafter, referred to as sudden throttle operation), the difference between the target revolution speed and the actual revolution speed becomes large in the same way as when the load suddenly changes, so the driver intends to increase the speed. Even though the throttle is operated with, the pump discharge amount at the time of the operation, on the contrary, suddenly decreases. For this reason, the actuator is suddenly decelerated immediately after the throttle is operated to give a shock, and the operability is poor.

Therefore, as disclosed in Japanese Patent Publication Nos. 61-18028 and 61-31318, when the difference between the target revolution speed and the actual revolution speed exceeds a certain value, a rapid throttle operation is performed. Therefore, a method has been proposed in which the ESS control is stopped for a certain period of time and the pump discharge amount is maintained at the discharge amount immediately before the change.

[Problems to be Solved by the Invention]

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

Therefore, the present invention provides a control method of a variable displacement pump capable of preventing the shock of the actuator due to the sudden change of the pump discharge amount at the time of such a sudden throttle operation and improving the operability.

[Means for solving the problem]

According to the invention of claim 1, an engine speed sensing control for obtaining a difference between a target engine speed set by an engine throttle and an actual engine speed, and controlling a discharge amount of a variable displacement pump according to the engine speed difference. In the control method of the variable displacement pump, the change amount of the target speed of the engine is detected, and the engine speed sensing control is performed when the throttle is slowly operated so that the change amount does not exceed a certain value. At the time of sudden throttle operation exceeding, based on the operating state immediately before the change, the subsequent pump discharge amount control pattern is selected from preset pump control patterns, and in accordance with the selected pump control pattern and at a constant cycle. After performing the pattern control to control the pump discharge rate while sampling the pump control signal with Based on the pump control signal sampled at the last sampling period in this pattern control, the engine is subjected to correction control for correcting the pump control signal so as to approach the engine speed sensing control signal sampled at the end of the pattern control. It shifts to speed sensing control.

According to a second aspect of the present invention, one of the pump control signal immediately before the change and the actual engine speed and the load state of the actuator driven by the pump are set as the operating state immediately before the change during the sudden throttle operation. It is used.

[Action]

According to this method, the normal ESS control is executed except during the sudden throttle operation, and at the time of the sudden throttle operation, based on the ESS control operating state immediately before the operation, the control pattern selected from the preset and stored control patterns is selected. The pattern control of the pump discharge amount is performed for a certain period of time according to the pump control pattern.

This prevents a sudden change in the pump discharge amount during a sudden throttle operation and a shock to the actuator due to this.

Then, after shifting to the original ESS control after this pattern control, sampling was performed at the end of the pattern control based on the pump control signal sampled at the last sampling cycle in the pattern control performed as described above. By performing the correction control for making the correction so as to approach the ESS control signal, it is possible to prevent a sudden change in the pump discharge amount during the transition.

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

〔Example〕

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

In FIG. 1, reference numeral 1 denotes an engine throttle, and a signal of a target rotation speed Ne of the engine 2 set by the operation of the engine throttle 1 is input to the engine governor.

The target speed Ne of this engine 2 is determined by the governor position detector 3
Further, the actual engine speed Ns is detected by the speed detector 4, and both speed signals are input to the controller 5.

This controller 5 includes an analog input section (A / D converter) 6, a digital input section 7, a central processing unit (CPU)
8, a storage device 9 including a ROM and a RAM, and a regulator drive unit 12 that outputs a pump control signal (tilt command current) i to a regulator 11 of a variable displacement pump (hereinafter, simply referred to as a 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 in the storage device 9. Further, the target rotation speed, the actual rotation speed, and the pump control signal are fetched (sampled) in the storage device 9 and stored and updated at regular sampling intervals.

 The internal structure of the CPU 8 will be described with reference to FIG.

Reference numeral 13 is a rotation speed difference calculating means for obtaining a difference ΔN between the target rotation speed Ne and the actual rotation speed Ns, and 14 is an ESS according to the rotation speed difference ΔN.
It is an ESS signal calculation means for calculating a control signal.

In this ESS control signal calculation means 14, the rotation speed difference Δ
When N does not exceed a fixed value, the coefficient K = 1, and when it exceeds N, a smaller control coefficient K is determined as the rotational speed difference ΔN increases, and the pump control signal is based on the determined control coefficient K is output to the output means 15 for the regulator driver 12 in FIG. Output.

That is, the ESS for reading the fluctuation of the engine load by the change of the rotational speed difference ΔN and reducing the discharge amount of the pump 10 when the load becomes large (when the rotational speed difference ΔN becomes large).
Control is performed.

Further, the CPU 8 is provided with a sudden throttle detecting means 16. The sudden throttle detecting means 16 detects a variation amount ΔNe per unit time of the target rotation speed Ne detected by the governor position detector 3 in FIG. 1, and when it exceeds a certain value, it is determined that the sudden throttle operation is performed. .

This sudden throttle operation signal is sent to the pattern selection means 17, where the subsequent control pattern is based on the pump control signal of the last sampling cycle in the ESS control operation state immediately before the sudden throttle operation, and the subsequent control pattern indicates the degree of sudden throttle. It is selected from various control patterns stored in advance in the storage device 9 of FIG. 1 based on the size.

The control pattern stored in the storage device 9 (which defines the change state of the pump control signal for each sampling period) is obtained as follows.

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

 Tentative determination of control pattern The control pattern is provisionally determined based on the above result.

Actual machine confirmation test Change the load by operating the actual machine and confirm that there is no shock. If there is a shock, change part of the control pattern and repeat the confirmation test.

Determining control pattern If the above shock is eliminated, the control pattern is determined.

As an example of this control pattern, FIG. 5 (a) (b)
3 shows a pattern in which the pump control signal is linearly changed (for each sampling period) with the passage of time.

Further, in FIG. 2, 18 is a pattern control signal calculating means for calculating a pattern control signal (pump control signal at the time of pattern control) is1 based on the selected control pattern, 1
Reference numeral 9 denotes a counter that performs a timing operation at the start of the pattern control, and compares with the pattern control within a predetermined time (t ₀ to t _{1 to} t _{2 in} FIG. 5) counted by the counter 19.
The correction control by the correction means 20 is continuously performed.

Next, the pump control operation by this method will be described with reference to the flowchart of FIG. 3, FIGS. 4 (a) to 4 (d), and FIG. 5 (a).
The graph of (b) is also used for the description.

When the control is started, various data such as the target speed Ne and the actual speed Ns are read (step S ₁ ). Then, based on the speed difference ΔN obtained by the speed difference calculating means 13 in FIG. The ESS control signal is generated by the control signal calculation means 14.
Is calculated (step S ₂ ). The reading of various data and the calculation of the ESS control signal are continuously performed even when the pattern control described later is performed.

Thereafter, whether or not a sudden throttle operation by sudden throttle detecting means 16 of FIG. 2 is determined (Step S _3),
If it is not a sudden throttle operation, ES
The S control is executed (step S ₄ , step ₅ ).

On the other hand, if it is determined that the rapid throttle operation in step S ₃ (shown A ₁ of FIG. 4 each figure a rapid throttle operation time), the flag is set (Step S _6), sudden throttle operation immediately before the ESS Based on the pump control signal of the last sampling period in control, the pattern control means 17 of FIG. 2 selects the subsequent control pattern (step S ₇ ).

Here from the pattern control is started, the flag of the rapid throttle operation is confirmed to have been set (Step S ₄₎ after using the function of the control pattern selected by the pattern selecting means 17, of FIG. 2 Pattern control signal calculation means
18 pattern control signal is1 is calculated by (step S _8).

At this time counting operation by the counter 19 is started (Step S _9), the count value t, t ₀ ~t ₁ in less time than the constant t ₁ predetermined [4 (c)
Pattern control period C ₁ )], the pattern control signal is1 is output as the pump control signal i (steps S ₁₀ and S ₁₁ ).

Note that after step S _11, the process returns to step S ₁ through step S _21, step S _2, Step S ₄ through step S ₃
Move on to. Here further step of S _8, step S _9, the operation proceeds step S _10, the procedure proceeds to step S ₁₂ when the count value t is larger than the constant t ₁ (pattern control period end).

In this way, the ES
By performing the pattern control instead of the S control, it is possible to prevent a sudden change in the pump discharge amount, which is a harmful effect of the ESS control, and control the pump discharge amount without shock of the actuator.

Then, when this pattern control period C ₁ elapses (NO in step S ₁₀ ), thereafter, a YES period in step S ₁₂ , that is, the correction control period of t _{1 to} t ₂ in FIG. 4C. The following correction control is performed in C ₂ .

First, a constant in step S _13, step S _14, which is sampled by the pattern control end (correction control start point), i.e. the ESS control signal IS is obtained based on the difference between the actual speed and the target rotational speed at this point The width (offset value) ± α is compared with the pump control signal (hereinafter referred to as the immediately preceding pattern control signal) is2 at the last sampling cycle in the above pattern control, and the correction value ( Value) is3 (= is2 + δ · nΔT or is2-δ)
・ NΔT) is output. In the formula in parentheses, ΔT is the sampling period, and n is the number of sampling periods.

Specifically, (a) is2 ≧ is + α case (NO in step S ₁₃ )
Then, in the first sampling cycle after the start of correction control, is2
The correction value δ is subtracted from the is2−δ value, and the correction value δ is successively subtracted from the is2 in the second sampling period, and the corrected value δ is output. (B) is2 ≦ is -α case (NO in step S ₁₄₎
Then, the value of is2 + δ obtained by adding the correction value δ to is2 in the first sampling cycle, and (is2 +
The correction value δ is sequentially added from is2 and output as the value of δ) + δ (steps S ₁₅ and S ₁₆ ).

After this, as in the case of pattern control, step
S ₂₁ , step S ₁ , step S ₂ , step S ₃ , step S
₄ , step S ₈ , step S ₉ , step S ₁₀ , step S
_12, proceeds to step S _13, the operation to shift is performed until correction control ends here to step S ₁₅ or step S _16.

As a result, the correction control signal is3 is shown in FIG.
ESS control signal i
The signal approaches s.

On the other hand, in is2> is-α in the case (YES at Step S _14), the flag reset as correction end (step S _17), ESS control signal IS is output as the pump control signal i.

When the count value t exceeds the constant t ₂ , (step S
If NO in ₁₂ ), the flag is reset in the same manner as above (step S ₁₉ ), and thereafter the ESS control signal is is changed to the pump control signal i.
Is output as (step ₂₀ ).

In step S _21, these pump control signal i, i.e. ESS control signal IS, pattern control signals is1, one of the compensation control signal is3 is, of FIG. 1 as control data (i ') made up to that It is written in the storage device 9 (step ₂₁ ).

In this way, when shifting from the pattern control to the original ESS control, the pump control signal is corrected so as to gradually approach the ESS control signal is, so that the shift is smoothly performed and a sudden change in the pump discharge amount at the time of the shift is prevented. Can be prevented.

The trend of the pump control signal shown in FIG. 4C is shown in more detail in FIG.

FIG. 5 (a) shows the case where the pump discharge amount is rapidly throttled in the acceleration direction from a large state, and FIG. 5 (b) shows the case where the pump discharge amount is rapidly throttled in the acceleration direction from the small state. Shown respectively.

According to the ESS control, as shown by the alternate long and short dash line in both figures, after the pump discharge amount suddenly decreases from the sudden throttle operation time point A ₁ , the pump discharge amount gradually increases as the actual engine speed approaches the target speed. It will be.

On the other hand, according to this method, the pump discharge amount gradually changes during the pattern control period from A ₁ point to A ₂ point and continues from A ₂ point to A ₃ point.
In the correction control period up to the point, the ESS control value is approached, and the ESS control value is almost overlapped with the ESS control value.

By the above control, it is possible to prevent a sudden change in the pump discharge amount due to a sudden throttle operation, and to smoothly change the pump discharge amount in accordance with the change in the actual engine speed. Therefore, the actuator speed can be changed smoothly as shown in FIG.

By the way, in the above embodiment, the pump control signal i immediately before the ESS control operation is set as the operation state immediately before the sudden throttle operation as the element (variable) for selecting the control pattern.
Although s is used, the same effect as the above embodiment can be obtained even when the actual engine speed immediately before is used.

Alternatively, in addition to these, a load detector 21 for detecting 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 state of the actuator, so that the pump discharge amount does not change suddenly and the engine horsepower is efficiently controlled. be able to.

〔The invention's effect〕

As described above, according to the present invention, on the premise of the engine speed sensing control method, the change amount of the target rotation speed of the engine is detected, and when the change amount exceeds a certain value, the operating state immediately before the change is set to the operating state immediately before the change. Based on this, the subsequent pump discharge amount control pattern is selected from preset pump control patterns, and after controlling the pump discharge amount according to the selected pump control pattern,
Based on the pump control signal sampled at the last sampling period in this pattern control, this pump control signal is corrected through the correction control to make it closer to the engine speed sensing control signal sampled at the end of the pattern control. Since the control shifts to the sensing control, it is possible to prevent a sudden change in the pump discharge amount immediately after the sudden throttle operation as in the past, or a shift to the engine speed sensing control, and to prevent a shock from occurring in the actuator. The sex can be improved.

Further, according to the invention of claim 2, as the operating state immediately before the change, the load state of the actuator driven by the pump is used in addition to the immediately preceding pump control signal or the actual rotational speed of the engine. More often,
More appropriate control can be performed.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of an apparatus for carrying out a control method according to an embodiment of the present invention, and FIG. 2 is a CP in the apparatus.
Fig. 3 is a block diagram showing the internal configuration of U, Fig. 3 is a flow chart for explaining the operation of the method, and Fig. 4 (a) is the state of change of the target engine speed after the sudden throttle operation. ) Is the same rotational speed change state, FIG. 5 (c) is the pump control signal change state, FIG. 5 (d) is the actuator speed change state, respectively. FIG. 5 (a) (b) Shows the change situation of FIG. 4 (c) in more detail, and FIG. 6 shows FIG. 4 (c) when the load condition of the actuator is also used as an element for pattern selection.
FIG. 1 ... Engine throttle, 2 ... Engine, 3 ... Engine governor position detector as target speed detecting means,
4 ... Rotation speed detector as actual rotation speed detection means, 5 ...
… Controller, 8 …… CPU of the same controller, 9 ……
Same memory device, 13 ... CPU speed difference calculation means, 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, 20 ... Correction control Comparison and correction means for

Claims (2)

(57) [Claims] Claim: What is claimed is: 1. A difference between a target engine speed set by an engine throttle and an actual engine speed is obtained, and engine speed sensing control for controlling the discharge amount of a variable displacement pump is performed according to the difference in engine speed. In the variable displacement pump control method, the amount of change in the target engine speed is detected, and the engine speed sensing control is performed when the throttle is slowly operated so that the amount of change does not exceed a certain value. At the time of a sudden operation, based on the operating state immediately before the change, the control pattern for the subsequent pump discharge amount is selected from preset pump control patterns, and the pump is controlled in accordance with the selected pump control pattern and at a constant cycle. After performing the pattern control to control the pump discharge rate while sampling the control signal, Based on the pump control signal sampled at the last sampling cycle in the turn control, the pump speed control signal is corrected through correction control so as to approach the engine speed sensing control signal sampled at the end of the pattern control. A method for controlling a variable displacement pump, characterized by shifting to sensing control. 2. As one of the operating states immediately before the change when the throttle is suddenly operated, one of the pump control signal immediately before the change and the actual engine speed and the load state of the actuator driven by the pump are used. The method for controlling a variable displacement pump according to claim 1, wherein