JPH0243899B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention controls the fuel injection amount of a prime mover and the discharge amount of a hydraulic pump based on a rotation speed deviation signal between a target rotation speed signal of the prime mover and an output rotation speed signal. This invention relates to a control device for a system including a prime mover and a hydraulic pump.

[Background of the invention]

FIG. 5 is a block diagram showing a conventional control device for a system including a prime mover and a hydraulic pump as disclosed in detail in Japanese Patent Application Laid-Open No. 57-65822.

In the figure, 1 indicates a prime mover such as a diesel engine, and 2 is a so-called electronic fuel injection pump that electrically controls the amount of fuel injected into the prime mover 1.
3 is a variable displacement hydraulic pump driven by the prime mover 1; 4 is a so-called electronic pump regulator that controls the tilt angle of the swash plate (or oblique shaft) of the hydraulic pump 3 by an electric signal; It is. Command rotation speed signal of prime mover 1 N ₃₀ (in this case, target rotation speed signal No.
) is set by the driver using the fuel throttle lever 5, while the output rotational speed signal N of the prime mover 1 is detected and output by the rotational speed detector 6, and the adder 7 outputs the target rotational speed signal No. Rotation speed signal N
The rotation speed deviation signal ΔN is calculated and output. The displacement of a rack (not shown) of the fuel injection pump 2 is detected by a rack position detector (not shown), and a rack position signal L is output. Adder 8 receives rotational speed deviation signal ΔN given as easy target position signal.
The rack position is controlled based on the deviation signal Lo between the rack position signal L and the rack position signal L, and the fuel injection amount of the fuel injection pump 2 is determined.

Further, 9 is a pump control function generator which inputs the pressure signal P from the pressure detector 11 provided in the discharge pipe 10 of the hydraulic pump 3 and the rotation speed deviation signal ΔN from the adder 7. A pump tilting signal _Xq for controlling the discharge amount is output to the regulator 4.

The rotational speed deviation signal ΔN increases as the load on the hydraulic pump 3 increases and the output rotational speed signal N decreases, and conversely, as the load on the hydraulic pump 3 becomes lighter and the output rotational speed signal N increases. becomes smaller.
Therefore, as ΔN increases, the electronic fuel injection pump 2 moves its easy position in the direction of increasing the fuel injection amount, increases the output of the prime mover 1, suppresses the decrease in the output rotational speed signal N, and also When becomes smaller, the fuel injection amount is reduced to prevent the output rotational speed signal N of the prime mover 1 from becoming overspeeded.

The input torque of the hydraulic pump 3 is proportional to the product of the swash plate tilting amount and the discharge pressure. Therefore, when the load on the hydraulic pump 3 increases (discharge pressure P rises), the output rotational speed signal N of the prime mover 1 decreases, and the rotational speed deviation signal ΔN increases, the pump control function generator 9 changes the value of ΔN. As this increases, the product _of the pump tilting amount signal The displacement amount signal _Xq is outputted so that the displacement amount signal Xq is decreased, and the discharge amount of the hydraulic pump 3 is decreased.

In the conventional control device for a system including a prime mover and a hydraulic pump configured as described above, the output of the prime mover 1 is regulated by the target rotation speed signal No (=Nso) commanded by the fuel throttle lever 5. It had the disadvantage of being accepted. That is, if the throttle lever 5 is used to command, for example, the maximum target rotation speed of the prime mover 1, the prime mover 1 will be driven at the maximum output rotation speed even when the load on the hydraulic pump 3 is small, resulting in a worsening of the fuel consumption rate. In addition, if a target rotation speed that is relatively low compared to the maximum target rotation speed is commanded by the throttle lever 5, when the load on the hydraulic pump 3 becomes large, the output of the prime mover 1 will be increased to the high output at the high target rotation speed. It is not possible to drive a large load. Therefore, the driver must constantly operate the fuel throttle lever 5 according to the load on the hydraulic pump 3 in order to solve the above problem, and this operation is not only troublesome but also requires skill. It was difficult to completely follow load fluctuations with the operating feel.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned drawbacks of the conventional control device, and when the load applied to the hydraulic pump is small, the prime mover is used in a region with relatively low rotation and relatively low output, and when the load becomes large, the motor is automatically activated. By increasing the target rotation speed, the prime mover can be used in a region with high rotation speed and high output, while also avoiding sudden changes in the discharge amount of the hydraulic pump when the target rotation speed increases, and improving fuel consumption and operability. The purpose is to improve.

[Summary of the invention]

In order to achieve this object, the present invention uses an increased rotational speed signal set in response to an increase or decrease in a rotational speed deviation signal, which is the difference between a target rotational speed signal and an output rotational speed signal, to a commanded rotational speed of a fuel throttle lever. The target rotation speed signal is added to the target rotation speed signal, and the fuel injection amount and the discharge amount of the hydraulic pump are controlled based on this target rotation speed signal, and the increase rate and decrease rate with respect to time of the increased rotation speed signal are set in advance. By limiting the load to below the value, when the load on the hydraulic pump is light,
Controls the prime mover output rotation speed based on a relatively low target rotation speed signal commanded by the throttle lever,
When the load on the hydraulic pump increases, the output rotation speed of the prime mover is controlled based on the high target rotation speed signal that increases in accordance with the increase in the rotation speed deviation signal, and the discharge amount of the hydraulic pump is controlled when the target rotation speed signal increases. This is to avoid sudden changes in the pressure and to smoothly operate the actuator driven by the hydraulic pump.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

FIG. 1 shows a control block diagram of a system including a prime mover and a hydraulic pump according to an embodiment of the present invention.
The same parts as in FIG. 5 are given the same reference numerals.

12 is an increased rotational speed generating means, that is, an increased rotational speed function generator, which receives the rotational speed deviation signal ΔN from the adder 7.
is input, and an increased rotational speed signal N′ _o is generated. 13
inputs the increasing rotational speed signal N′ _o from the increasing rotational speed function generator 12 to the increasing rate limiting means, that is, the increasing rotational speed change rate limiting device, and limits the maximum value of the increasing rate or decreasing rate for that time. Outputs an increased rotational speed signal _No. Reference numeral 14 denotes an adder provided between the fuel throttle lever 5 and the adder 7, which adds an increased rotation speed signal No to the command rotation speed signal _Nso of the fuel throttle lever 5 to obtain a target rotation speed signal No. , this No. is output to the adder 7.

FIG. 2 shows an example of the functional relationship ΔN-N' _o of the increased rotational speed signal generator 12.

In Figure 2, the vertical axis shows the increased rotational speed signal N' _o and the horizontal axis shows the rotational speed deviation signal ΔN. When ΔN increases and exceeds point a, the rotational speed increases in proportion to the magnitude of ΔN. When the signal N′ _o increases and ΔN reaches point b,
N′ _o is the preset N′ _o max.
Further, the functional relationship of ΔN-N' _o may be such that when ΔN exceeds a set value a, N' _o max is reached in a stepwise manner.

FIG. 3 shows one embodiment of the specific configuration of the increased rotational speed change rate limiting device, which is an integrator configured with an electronic circuit.

The rate of change of the output N _o with respect to the input N' _o over time is determined by the resistance R and the capacitance C of the capacitor. That is, by increasing the resistance R or the capacitor capacity, the rate of change of N _o relative to N' _o per time can be reduced.

Figure 4 shows N _o when N′ _o changes in a step-like manner.
, where the vertical axis represents voltage V and the horizontal axis represents time t. When N′ _o is output through an integrator, the output N′ _o (solid line) _is
(Dotted line) has a characteristic having a slope, and the rate of change per time can be limited to a certain value or less.

If the rate of change of the increased rotational speed N′ _o corresponding to time is not limited, when the load on the hydraulic pump increases, the increased rotational speed signal generator 12 will output N′ _o directly to the adder 14, and the target rotational speed No. is increased by N′ _o . However, since the prime mover 1 is a large inertial body with a flywheel, the output rotational speed signal N does not increase immediately, so the rotational speed deviation signal ΔN which is the difference between the target rotational speed signal No. and the output rotational speed signal N becomes large, and due to this ΔN, the pump control function generator 9
reduces the displacement amount signal _Xq of the hydraulic pump 3 to reduce the discharge amount.

Here, if N′ _o changes suddenly, the hydraulic pump 3
Since the discharge amount of the hydraulic pump 3 also changes suddenly, the speed of an actuator (not shown) driven by the hydraulic pump 3 changes suddenly, resulting in poor operability such as a shock.

As described above, by limiting the increased rotational speed signal N' _o and the rate of change to below a certain value and outputting it as N _o , sudden changes in the speed of the actuator can be avoided.

Next, the operation shown in FIG. 1 will be further explained. When the command rotation speed signal Nso of a relatively low rotation speed is commanded by the fuel throttle lever 5, the output rotation speed signal N of the prime mover 1 and the command rotation speed signal Nso are close to each other when the load on the hydraulic pump 3 is small. Since Nso becomes the target rotational speed signal No., the fuel injection amount of the fuel injection pump 2 and the hydraulic pump 3
The discharge amount is controlled.

From this state, when the load on the hydraulic pump 3 increases and the output rotation speed signal N of the prime mover 1 decreases,
When the rotational speed deviation signal ΔN increases and ΔN exceeds a, the increased rotational speed generator 12 generates an increased rotational speed signal.
_N'o is generated, and the increased rotational speed signal _No is added to the commanded rotational speed signal Nso by the adder 13 via the increased rotational speed change rate limiting device 13 to become the target rotational speed signal No. Therefore, the fuel injection amount of the fuel injection pump 2 and the discharge amount of the hydraulic pump depend on the command rotation speed signal Nso commanded by the throttle lever 5 _.
It will be controlled by the high target rotation speed signal No.

According to the above embodiment, the following effects are achieved.

(1) When the load on the hydraulic pump 3 is small, the prime mover 1 can be used in a low rotational speed and low output range to improve the fuel consumption rate and reduce the noise generated by the prime mover 1.

(2) When the load on the hydraulic pump 3 increases, the target rotation speed of the prime mover 1 is automatically increased, and the prime mover 1 can be operated in a high rotation speed and large output range.

(3) The prime mover 1 responds to changes in the load on the hydraulic pump 3.
Since the target rotation speed can be automatically followed, the troublesome operation by the driver is eliminated and the operability is improved.

(4) When the target rotation speed increases, the rate of change of the increasing rotation speed signal over time is limited to a certain value or less.
It is possible to avoid sudden changes in the discharge amount of the hydraulic pump, enabling smooth drive of the actuator and improving operability.

〔Effect of the invention〕

According to the present invention described above, in a control device for a system including a prime mover and a hydraulic pump, when the load on the hydraulic pump is small, the prime mover is controlled in a low output region, and when the load on the hydraulic pump is large, the prime mover is controlled in a high output region. It is possible to automatically control the rotation speed of the prime mover, which is controlled by The operability can be extremely improved.

[Brief explanation of the drawing]

FIG. 1 is a control block diagram of a system including a prime mover and a hydraulic pump according to the present invention, FIG. 2 is a diagram showing an example of a function set for the increased rotation speed generator of FIG. 1, and FIG.
The figure shows an example of a specific configuration of the increasing rotational speed change rate limiting device, Fig. 4 shows the characteristics of the output N _o with respect to the input N' _o , and Fig. 5 shows a conventional system including a prime mover and a hydraulic pump. FIG. 1... Prime mover, 2... Fuel injection pump, 3...
Hydraulic pump, 4... Regulator, 5... Fuel throttle lever, 6... Rotation detector, 7, 8, 1
4... Adder, 11... Pump control function generator,
12... Increased rotation speed function generator, 13... Increased rotation speed change rate limiting device, N... Output rotation speed signal,
No...Target rotation speed signal, _No , N′ _o ...Increase rotation speed signal, Nso...Command rotation speed signal, ΔN...Rotation speed deviation signal.

Claims (1)

[Claims] 1 includes a prime mover and a hydraulic pump driven by the prime mover, obtains a rotation speed deviation signal that is the difference between the target rotation speed signal and the output rotation speed signal of the prime mover, and calculates the rotation speed of the prime mover based on this rotation speed deviation signal. A control device for a system including a prime mover and a hydraulic pump that controls the fuel injection amount and the discharge amount of the hydraulic pump outputs an increased rotation speed signal that becomes larger as the value of the rotation speed deviation signal increases. and increase rate limiting means for limiting the increase rate of the increased rotational speed signal outputted from the increased rotational speed generation means to a preset value or less, and the increased rotational speed signal output from the increased rotational speed limiting means. is,
A control device for a system including a prime mover and a hydraulic pump, characterized in that an increased rotational speed signal whose increase rate is limited is added to a commanded rotational speed of a fuel throttle lever to obtain the target rotational speed signal.