JPH0261340A - Drive system control device including internal combustion engine and hydraulic pump - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a drive including an internal combustion engine and a hydraulic pump in a working machine equipped with a variable displacement hydraulic pump driven by an internal combustion engine, such as a hydraulic excavator. It relates to a system control device.

[Conventional technology]

Conventionally, in working machines such as hydraulic excavators that drive an internal combustion engine and a hydraulic pump to generate hydraulic power, (a) Individual control system ( b) Cross sensing method (c) Engine speed sensing method 03 types 11
'4n system was used.

For example, in the case of two hydraulic pumps, the individual control method (b) allocates 1/2 of the internal combustion engine's maximum output horsepower to each hydraulic pump, and detects the circuit pressure of each hydraulic pump independently. This method controls the discharge amount of the pump. With this system, even if one hydraulic pump is under no load, the other hydraulic pump cannot utilize its surplus horsepower, which can lead to problems.

The cross-sensing method (b) uses two hydraulic pumps to mutually transmit their respective circuit pressures, so that when the load on one hydraulic pump is light, the other hydraulic pump uses a portion of its excess horsepower. It has been made available. Although this method is superior to the individual control method in terms of horsepower control, the structure of the regulator that controls the pump discharge amount is complicated.

On the other hand, the engine speed sensing method (c) detects a decrease in the rotational speed of the internal combustion engine and limits the discharge amount of the hydraulic pump, and is the most excellent method in terms of horsepower utilization. As a conventional example, for example, S A E
-paper 760687 (T, P.

Written by Neal Electrohydraulic Co
ntrol of Hydrostatic Tra
This method is excellent in principle in that it detects a drop in the rotational speed of the internal combustion engine and limits the tilting angle of the hydraulic pump. This S
In the hydraulic pump control device (hereinafter referred to as "anti-stall circuit") described in A The deviation ΔN of the output signal of the rotation detector that detects the actual rotation speed of The input torque of the pump is limited.

[Problem to be solved by the invention]

By the way, the above SAE-paper 76068
The control device described in No. 7 had the following problems.

That is, in order to use the output of the internal combustion engine most effectively with the hydraulic pump, it is necessary to control the swash plate tilt angle of the hydraulic pump to decrease immediately before the fuel injection amount reaches its maximum value. but,
Generally, a mechanical all-speed governor is used in addition to an anti-stall circuit to control the fuel injection amount of an internal combustion engine. For this reason, in the conventional device described above, it is difficult to control the swash plate tilt angle to decrease immediately before the fuel injection amount reaches the maximum value. In other words, the mechanical all-speed governor controls the fuel injection amount by the balance between the centrifugal force of the flyweight and the spring.Since the centrifugal force of the flyweight is proportional to the square of the output rotation speed, the accelerator lever
If the set rotational speed differs, the adjustment amount of the fuel injection amount due to the increase/decrease in the rotational speed deviation ΔN will differ. Therefore, even if the value of the rotational speed deviation ΔN that reaches the maximum fuel injection amount at the rotational speed that generates the rated output is the same as the value of the rotational speed deviation ΔN that starts reducing the amount of tilting of the swash plate of the anti-stall circuit. Even if they can be set, if the set rotation speed is changed using the accelerator lever, there will be a "discrepancy" in these values, making it impossible to effectively use the output of the internal combustion engine as input to the hydraulic pump.

Further, the regulation range of the mechanical all-speed governor is very small at 150 rpm, compared to a wide range of set rotation speeds of 500 to 2000 rpm. And the mechanical all speed governor is this 15
From the minimum fuel injection amount to the maximum fuel injection amount between 0 rpm,
That is, it controls the internal combustion engine from the lowest output to the highest output. By the way, as mentioned above, in order to make the most effective use of the output of the internal combustion engine with the hydraulic pump, it is necessary to accurately set the point at which the swash plate tilting amount of the anti-slip circuit begins to decrease immediately before the maximum fuel injection amount of the internal combustion engine. Moreover, it is necessary to accurately set the above-mentioned reduction start point at any set rotational speed of the internal combustion engine.

However, as mentioned above, the regulation range of the mechanical all-speed governor is extremely small, so slight manufacturing errors or assembly errors for each product, or errors due to aging can have a large effect, making it extremely difficult to set the above-mentioned starting point of decrease. It is.

Further, even if an electronic governor using electronic elements is used to control the fuel injection amount, similar problems arise due to variations in accuracy of electronic components such as resistors, capacitors, and operational amplifiers.

The purpose of the present invention is to solve the problems in the above-mentioned prior art,
The setting relationship between the fuel injection amount and the input torque of the hydraulic pump can be maintained as set in advance at any set rotation speed of the internal combustion engine, thereby allowing the hydraulic pump to use the output of the internal combustion engine most effectively. It is an object of the present invention to provide a control device for a drive system including an internal combustion engine and a hydraulic pump, which is capable of providing a stable control system.

[Means to solve the problem]

To achieve the above object, the present invention includes an internal combustion engine controlled by adjusting the fuel injection amount of a fuel injection pump, and a small number of variable displacement hydraulic pumps driven by the internal combustion engine. an operating device for setting a target rotation speed of the internal combustion engine and generating a corresponding target rotation speed signal for the drive system; and a rotation control device for detecting the output rotation speed of the internal combustion engine and generating an output rotation speed signal corresponding thereto. a calculation device that calculates a rotation speed deviation signal that is the difference between the target rotation speed signal and the output rotation speed signal; and a calculation device that calculates a rotation speed deviation signal that is the difference between the target rotation speed signal and the output rotation speed signal; In a control device for a drive system including an internal combustion engine and a hydraulic pump, the input torque reducing means reduces the input torque of the hydraulic pump as the input torque increases. The target rack displacement amount of the fuel injection pump is increased based on the number deviation signal, and when the rotation speed deviation signal reaches another set value near the maximum fuel injection amount, which is slightly larger than the set value, the target rack displacement amount is increased. a first storage section that stores a function for suppressing an increase in the rack displacement amount; and a fuel injection amount that controls the fuel injection amount by adjusting the rack position of the fuel injection pump based on the target rack displacement amount retrieved from the storage section. a control device, and
The input torque reducing means includes a pressure detection device that detects the discharge pressure of the hydraulic pump and generates a pressure signal corresponding thereto, and an input torque signal that is inputted to the pressure signal for each rotational speed deviation signal that exceeds the predetermined set value. a second storage section that stores a tilting amount target value that sets the torque to a predetermined value; and a second storage section that stores a tilting amount target value that sets the torque to a predetermined value; A swash plate tilting angle control device for controlling the tilting angle.

[Effect]

When a target rotation speed Nr is given by the operating device, a rotation speed deviation signal Δ is generated from the target rotation speed Nr and the output rotation speed Ne of the internal combustion engine.
N is determined, a target rack displacement amount M is determined from the first storage section based on this rotation speed deviation signal ΔN, and the fuel injection amount is controlled so that the rack position becomes the target rack displacement amount M. At the same time, the target swash plate tilting amount Xi is retrieved from the second storage section based on the same rotational speed deviation signal ΔN as above and the discharge pressure P of the hydraulic pump, and the slant viW4 slant angle is controlled to become this value. do.

As the load on the hydraulic pump increases, the output rotation speed Ne of the internal combustion engine decreases, the rotation speed deviation signal ΔN gradually increases, the target rack displacement fiM gradually increases, and the fuel injection amount is controlled to increase. The power of the internal combustion engine increases. Further, when the load on the hydraulic pump increases, the rotational speed deviation signal ΔN reaches the other set value ΔN, and the increase in the fuel injection amount is restricted. That is, the output of the internal combustion engine reaches near the maximum output point. However, from the time when the predetermined set value ΔN0 is exceeded immediately before reaching the set value ΔN, the target swash plate tilting amount The amount of tilting of the swash plate is controlled to achieve a predetermined input torque, and as a result, the torque of the hydraulic pump is reduced, so that the output of the internal combustion engine remains at its maximum and is balanced with the input torque of the hydraulic pump.

Moreover, since the settings of the set values ΔN1 and ΔN0 are stored in the first and second storage sections in advance, they can be set accurately, and the target values of the fuel injection amount and the amount of swash plate tilting of the hydraulic pump can be set at the same rotation speed. Since control is performed using the deviation signal, the relationship between the two can be reproduced with high accuracy no matter what target rotation speed is set using the operating device.

Furthermore, in controlling the amount of swash plate tilting of the hydraulic pump, the input torque to be controlled is determined as the target swash plate tilting ffl X H from the rotation speed deviation signal ΔN and the discharge pressure P of the hydraulic pump. A control system that is stable against changes can be obtained.

〔Example〕

Hereinafter, the present invention will be explained based on illustrated embodiments.

FIG. 1 is a system diagram showing a system of an internal combustion engine and a variable displacement pump according to an embodiment of the control device of the present invention. In FIG. 1, 1 is an internal combustion engine, and 2 and 3 are variable displacement hydraulic pumps (hereinafter simply referred to as hydraulic pumps) driven by the internal combustion engine 1. In FIG. 4 and 5 are swash plate operating mechanisms for controlling the tilting angle of the swash plate (or slant shaft, hereinafter referred to as swash plate) of the hydraulic pumps 2 and 3, respectively, and a specific example of its configuration is shown in FIG. This is an indication. 6 is a fuel injection pump for the internal combustion engine 1, and this fuel injection pump 6 supplies a desired amount of fuel to the internal combustion engine by operating a rack provided thereon. A concrete example of the structure of the rack driving means of this fuel injection engine pro is shown in FIG. Reference numeral 7 indicates an operation amount detector for a throttle lever (not shown) of the internal combustion engine 1, and reference numeral 8.9 indicates an operation lever (not shown) for externally controlling the maximum value of the swash plate tilting amount of the hydraulic pumps 2 and 3. ) manipulated variable detector, 1
0 is a detector for detecting the output rotation speed of the internal combustion engine 1, and 11 is a detector for detecting rack displacement of the fuel injection pump 6. 12 is a control device for the internal combustion engine 1, and is this control bag? ! i1
2 is the throttle lever operation amount signal from the detector 7 (target value of internal combustion engine 10 revolutions)? a, a rack operation signal 12a is output to the fuel injection pump 6 based on the internal combustion engine 10 rotational speed signal 10a from the detector 10 and the rack displacement signal 11a of the fuel injection pump 6 from the detector 11; The rotation speed deviation signal 12b is sent to the hydraulic pump 2.
Rule of 3? Output to I device 13.

The control device 13 of the hydraulic pump 2.3 receives an external operation signal 8a for the amount of tilting of the swash plate of the hydraulic pump 2, an external operation signal 9a for the amount of tilt of the swash plate of the hydraulic pump 3, and a signal for the amount of tilt of the swash plate of the hydraulic pump 2. 4
a, swash plate tilting amount signal 5a of hydraulic pump 3, pressure detector 1
4, the discharge pressure signal 14a of the hydraulic pump 2 detected by the pressure detector 15, and the discharge pressure signal 15 of the hydraulic pump 3 detected by the pressure detector 15.
a and the rotational speed deviation signal 12b of the internal combustion engine 1 given from the control device 12 of the internal combustion engine 1, the swash plate operation signal 13a of the hydraulic pump 2 and the swash plate operation signal 13b of the hydraulic pump 5 are set for each hydraulic pump. Swash plate operation mechanism 4,
Output to 5.

A specific example of the above-mentioned fuel injection pump 6 and rack operating device will be described with reference to FIG. In this figure, the same reference numerals as in FIG. 1 indicate the same parts. The amount of fuel injected into the internal combustion engine 1 has a functional relationship with the displacement of the rack 16. This rack 16 is driven by a movable wire wheel 17. 18 is a yoke, 19 is a permanent magnet, and 20 is a rack return spring. Reference numeral 21 denotes a current amplifier, which receives the rack operation signal 12a from the control device 12 of the internal combustion engine 1, converts it into a DC current signal or pulse width modulation signal 21a, and drives the movable wire wheel 17. Rack displacement detector 11
The output is sent to the control device 1 of the internal combustion engine 1 as a rack displacement signal 11a via an amplifier or a waveform shaping circuit 22.
Return to 2.

A specific embodiment of the swash plate operating mechanism 4 of the hydraulic pump 2 described above will be described with reference to FIG. In this figure, the same reference numerals as in FIG. 1 indicate the same parts. Swash plate 2a of hydraulic pump 2
are driven by hydraulic cylinders 23a and 23b. The hydraulic cylinders 23a, 23b are controlled by four second-position W2-way magnetic valves 24-27. That is, the magnetic valves 24 and 2
When the solenoids 24a and 25a of the hydraulic pump 2 are excited, the pressure oil from the pilot hydraulic pressure a28 acts on the hydraulic cylinder 23a, and the hydraulic cylinder 23b is connected to the tank 29, so that the amount of inclination of the swash plate 2a of the hydraulic pump 2 increases. Conversely, when the solenoids 26a and 27a of the electromagnetic valves 26 and 27 are energized, the amount of tilting of the swash plate of the hydraulic pump 2 decreases. Then, when the solenoids 25a and 27a of the electromagnetic valves 25 and 27 are energized, all the electromagnetic valves 24 to 27 close the circuit, so that the amount of tilting of the swash plate of the hydraulic pump 2 maintains that state. 3
0 is a detector that detects the amount of tilting of the swash plate 2a of the hydraulic pump 2, and its output signal is sent to the pump control device 13 as a swash plate rotation amount signal 4a via an amplification amount or waveform shaping circuit 31.
will be returned to. Since the swash plate operating mechanism 5 of the hydraulic pump 3 is similarly configured, detailed explanation thereof will be omitted.

Next, the control procedure in the control device 12 of the internal combustion engine 1 is explained as follows.
The diagram will be explained. FIG. 4 is a control flowchart when a microcomputer is used as the control device 12.

First, in step 40, the state quantities, that is, the throttle lever operation amount (target rotational speed Nr), output rotational speed No., and rack displacement Z are read and stored in appropriate storage addresses in the storage section of the control II device 12. Next, in step 41, the rotation speed deviation ΔN=N r -N e of the internal combustion engine 1 is calculated and the result is stored, and in step 42, the value of the rotation speed deviation ΔN is used as a signal 12b to control the hydraulic pump control device 1.
Output to 3. Next, it is determined whether or not it is idling from the value of the target rotation speed Nr, and if it is idling, step 4
4, the rack displacement target function Mwfi (Δ
N) and find the rack displacement target value M during idling.
Determine the value of and move on to step 45.

Here, the rack displacement target function has a form as shown in FIG. That is, the rack displacement target value M is a monotonically increasing function with respect to the rotation speed deviation ΔN.

In Figure 5, the function f (ΔN) is a predetermined set value ΔN
Although shown as a broken line function with 1 as a breaking point, it is not necessarily such a broken line, but may be a curved line. Note that the reason why the linear function is used is to gradually increase the output torque just before reaching the maximum fuel injection amount even at a rotation speed below the maximum torque point of the internal combustion function. There is also a method in which three types of rack displacement target value functions are prepared, one for idling, one for medium speed, and one for high speed, and used depending on the target rotational speed Nr. Figure 4 shows this method. That is, if it is not idling in step 43, it is determined in step 46 whether it is medium speed or high speed (the maximum value of the medium speed rotation range is indicated by the value Nro), and if it is high speed, step 47 is performed. Rack displacement target value function M = f h (ΔN
), and determine the rack displacement target value M at this time, and then proceed to step 45. In addition, in case of medium speed, step 48
Then, the rack displacement target value function M=f, (ΔN) for medium speed is inquired, and the value of the rack displacement target value M at this time is determined, and then the process moves to step 45.

Hand: In li 45, from the output rotation speed Ne, the maximum value M, A, of the rack displacement target value M written in advance in the ROM is calculated.
=g (Nθ), and in the next step 46, the value of this rack displacement target value M and its maximum value M m m x are compared. If M > Mmax, the value of M is replaced with M□8 in step 47, and the process moves to step 48. If M < M m m X, do step 48 without changing the value of M.
Move to.

Maximum value of rack displacement target value Mmsx = g (N e
) is in a relationship that decreases with respect to the output rotational speed Ne as shown in FIG. The purpose of this is as follows. That is, in general, the fuel injection amount per cycle of the fuel injection pump 6 tends to increase as the rotational speed of the internal combustion engine 1 increases when the rack displacement is significant. Therefore, as the rotational speed decreases, the output torque decreases. Therefore, if the maximum value of rack displacement is adjusted to a large value in order to secure torque in the low rotation range, the amount of fuel injected in the high rotation range will become too large and incomplete combustion will occur, causing the internal combustion engine to black out. Smoke comes out. In order to overcome such problems, as shown in FIG. 6, the maximum value M3. It is sufficient to set the relationship with X to a downward sloping characteristic. This is known as Angleich.
) characteristics. This characteristic is achieved with a mechanical governor by combining very complicated mechanisms, but it can be achieved very easily by using a microcomputer as the control device.

After determining the target value M of rack displacement as described above, in step 48 shown in FIG. It outputs to the current amplifier 21 shown in FIG. 3 and returns to the beginning.

Next, the control procedure in the pump control device 13 will be explained with reference to FIG. FIG. 7 is a control flowchart when the pump control device 13 is implemented using a microcomputer.

First, in step 50, the state quantity of the drive system related to the hydraulic pump 2,
In other words, the external operation signal X of the hydraulic pump 2 and the amount of swash plate tilting Y
, the rotational pressure P and the rotational speed deviation ΔN of the internal combustion engine 1 are read and stored. Next, in step 51, input torque control function f,
A swash plate tilting amount command value X)l based on (ΔN, P) is determined. The procedure for determining the swash plate tilting amount command value X will be explained.

The input torque T of the hydraulic pump 2 is proportional to the product of the swash plate tilting amount Y of the hydraulic pump 2 and the discharge pressure P. In this embodiment, the input torque T is the output rotation speed Ne of the internal combustion engine 1.
In other words, the rotational speed deviation ΔN is controlled according to the increase or decrease in the rotation speed deviation ΔN. Rotational speed deviation Δ in such control
The relationship between input torque T of the hydraulic pump and N is shown in FIG.

In other words, the input torque T of the hydraulic pump is ΔN≦ΔNO(
The value ΔN0 is the maximum value T'nax (a predetermined set value), and when the rotation speed deviation ΔN exceeds the set value ΔN0, it decreases as the rotation speed deviation ΔN increases, and the rotation speed deviation ΔN exceeds the set value ΔN mix. is the input torque, and T is the minimum value T.

It is determined that

By the way, as mentioned earlier, the input torque T of the hydraulic pump is proportional to the product of the discharge pressure of the hydraulic pump and the amount of tilting.

Therefore, in this embodiment, the input torque T is obtained according to the function shown in FIG. 8, which corresponds to a certain rotational speed deviation ΔN. Then, the swash plate tilt amount (target value of the swash plate tilt amount) is determined so that the product of the detected discharge pressure and the swash plate tilt amount becomes the obtained input torque T. If the tilting of the swash plate is controlled by the amount of tilt of the swash plate determined in this way, it is possible to obtain the corresponding input torque T in FIG. 8 for a certain rotational speed deviation ΔN. The 9th one expresses these relationships.
This is the input torque control function f, (ΔN, P) shown in the figure.

The horizontal axis in FIG. 9 is the circuit pressure P, and the vertical axis is the input horsepower control function f.

The target value X of the swash plate tilt amount is based on (ΔN, P).

The input torque control numerical values f, (ΔN, P) are a hyperbolic group or an approximate hyperbolic group, and are represented by a curve group that satisfies the input torque characteristics shown in FIG. Using the rotational speed deviation ΔN of the internal combustion engine 1, the corresponding input torque function f is determined, and the optimum swash plate tilting amount command value X1 is determined from the hydraulic circuit pressure P.
4 can be determined. That is, the input torque control function f.

(ΔN, P) corresponds to the size of the rotational speed deviation ΔN, and f
l. (ΔNo, P), f++ (ΔN,,P)...
....fl(ΔN!, P) and a plurality of function tables are stored in advance in the storage section of the control device 13, and a function table corresponding to the rotation speed deviation closest to the actual rotation speed deviation is stored in advance. The desired swash plate tilt amount command value may be calculated using linear interpolation.

At this time, when the rotation speed deviation ΔN is less than the set value ΔNo,
The input torque function f, is a function f,. is calculated, and as the rotation speed deviation ΔN becomes larger than the set value ΔN0, the function fl
l"fl!...fli is required.

In addition, as a method for finding the torque control function f,
An m-type method may also be used. This is done by moving one hyperbola fo (P) in parallel according to the value of the rotational speed deviation ΔN as shown in Fig. 10, and tilting the swash plate corresponding to the hydraulic circuit pressure P and the rotational speed deviation ΔN. This is to find the target value XII of the quantity. The method of parallel movement at this time will be described below using FIG.

In Figure 11, the hyperbola f0 (ΔP) that is now the standard
Assume that a relationship between the pressure P and the swash plate tilting amount command value XM is used so that the absorption torque T0 of the hydraulic pump 2 becomes the minimum absorption torque T0. At this time, ΔP”g + (ΔN) changes according to the rotational speed deviation ΔN of the internal combustion engine 1.
Using the function f, replace the pressure signal P with P'=P-ΔP.

If we try to find X)l from
-ΔP), the shape is obtained by moving r, (P) by ΔP in the horizontal axis direction.

This curve is quite different from the curve where the absorption torque is approximately constant. Therefore, one more point is the rotation speed deviation ΔN
The target value XH of the swash plate tilting amount is corrected using a function ΔX=gz(ΔN) that changes according to. That is, the calculation XH-fa(P-ΔP)+ΔX is performed to move the curve fo (P-ΔP) by ΔN in the vertical axis direction. The resulting curve is shown in FIG. 11 as a broken line. When translating in this way, a fairly good curve of constant absorption torque is obtained depending on the respective rotational speed deviation.

Here, in order to control the absorption torque T of the hydraulic pump 2 to decrease in the form shown in FIG. 8 with respect to the increase in the rotation speed deviation ΔN of the internal combustion engine 1, a correction function ΔP=g+(ΔN) is used.
, Δx=g2 (ΔN) have the shapes shown in FIGS. 12 and 13, respectively.

FIG. 14 shows the procedure described above in the form of a flowchart. Note that if a straight line is used instead of a hyperbola as the reference input torque control function f0, the error from the constant human torque curve will increase; Since the stability is much better than the method described above, the use of a straight line as the input torque control function f0 does not go against the spirit of the present invention.

X1l=f+(Δ
N, P) are determined as above, but in this case,
The setting value ΔN of the rotational speed deviation ΔN at the corner point where the fuel injection amount starts to be limited as shown in FIG. 5 is the rotational speed deviation at which the input torque T of the hydraulic pump starts to be limited as shown in FIG. Δ
Since it is set to a value slightly larger than N0, the output of the internal combustion engine can be used most effectively as the human torque of the hydraulic pump.

Returning to FIG. 7 again, the control procedure starting from step 52 will be explained. After determining the target value XH of the swash plate tilting amount regarding the human torque from the input torque control function fl (ΔN, P), the value is temporarily stored and the process moves to the next step 52. Step 5
2, when the circuit pressure P increases abnormally, the swash plate tilting i1Y is reduced regardless of the lever operation amount XL and the target value Xll for limiting the input torque, and the relief valve (not shown) of the hydraulic circuit is activated. This is to prevent pressure oil from relieving itself and causing energy loss. For this purpose, a function xc =fz (P) as shown in FIG. 15 is prepared in the storage section. By referring to this function, the target value Xe of the swash plate tilting amount according to the circuit pressure is determined.

Next, in step 53, the target values XL, X, l, and Xc of the swash plate tilt amount determined in the above steps are compared, and the minimum value is set as the target value of the swash plate tilt l according to Hiiragi. Select as X,
The process moves on to step 54, which is control of the amount of tilting of the swash plate.

Next, the hydraulic pump control routine executed in step 54 is
This will be explained using Figure 6. First, in step 61, the target value X of the swash plate tilting amount of the hydraulic pump 2, the tilting angle X of the hydraulic pump 2,
. and the tilting angle deviation of pump 2 Zt ”'X Xr.

Calculate. Subsequently, in step 62, it is determined whether the tilt angle deviation Z2 of the pump 2 is positive or negative.

If the result is positive, it is checked in step 63 whether the tilt angle deviation Z2 is larger than the dead zone Δ. If Zz > Δ, the process moves to step 64, and a command to increase the tilting angle of the hydraulic pump 2 (the solenoid 24a of the solenoid valve 24, 25 shown in FIG.
25a is excited (↑ command) and returns to the main routine. If Zz<Δ in step 63, then in step 65 a command to hold the tilting angle of the hydraulic pump 2 (electromagnetic valve 25.2 shown in FIG. 3) is issued.
A command to excite the solenoids 25a and 27a of No. 7 is output, and the process returns to the main routine. In step 62, tilt angle deviation Z2
If the value of is negative, the process moves to step 66, the absolute value of the tilt angle deviation Z2 is taken, and 22=1221 is newly set. Next step 6
In step 7, the magnitude of the tilt angle deviation Z2 and the dead zone Δ is compared. Then, if Zz>Δ, in step 6B, a command to reduce the tilting angle of the hydraulic pump 2 (the solenoid 26a of the electromagnetic valve 26, 27 shown in FIG. 3) is issued.

27a) and returns to the main routine. If Z<A in step 57, the process moves to step 65, issues a command to maintain the tilt angle of the hydraulic pump 2, and returns to the main routine. Although the explanation so far relates to the hydraulic pump 2, the control routine for the hydraulic pump 3 is also similar to this, so the explanation will be omitted.

The hydraulic pump 2 has been controlled in the steps 50 to 54 shown in FIG. 7 above, but the same procedure is also performed for the hydraulic pump 3, and once that is completed, the process returns to the beginning and repeats the same control procedure. Here, if the absorption horsepower of hydraulic pump 2 and hydraulic pump 3 is to be distributed equally, XH determined in step 51 can be used as is in step 55, so the procedure for determining XH is as follows. 55, it can be omitted.

The above explanation has been about a so-called single-tilt type hydraulic pump in which the swash plate tilting amount Y of the hydraulic pumps 2 and 3 can take only positive values, but a so-called double-tilt type hydraulic pump in which Y can take positive and negative values A similar concept can be applied to a hydraulic closed path drive device using a hydraulic pump.

In addition, in the above-mentioned embodiment, in order to make the content of the present invention easier to understand, the control device 12 of the internal combustion engine 1 and the control device 13 of the hydraulic pump were explained as separate hardware.
It is also possible to construct the same hardware using two microcomputers.

[Effects of the Invention] As described above, in the present invention, in order to control the fuel injection amount, the function of the target rack displacement amount with respect to the rotational speed deviation signal ΔN is stored in the first storage section, and the hydraulic pump For input torque control, the function of the rotational speed deviation signal ΔN and the tilting amount target value for the hydraulic pump discharge pressure, which is the same as above, is stored in the second storage section, so that the fuel injection amount and the hydraulic pump's The target value of the swash plate tilting amount is controlled at the same time by the same rotation speed deviation signal, and no matter what value is set as the target rotation speed by the operating device, the relationship between the two can be reproduced with high accuracy. Ru.

In addition, in the above-mentioned storage in each storage section, the set value ΔN3 at which the increase in fuel injection amount begins to be restricted and the set value ΔN0 at which the input torque begins to decrease are also stored, so accurate settings can be made. These set values Δ
N1 is the set value ΔN.

Since the value is set to a slightly larger value, the output of the internal combustion engine can be utilized to the maximum extent as the input torque of the hydraulic pump. When this is combined with the above-mentioned effect of highly accurate reproducibility, this has the effect that the output of the internal combustion engine can be utilized to the maximum extent by the hydraulic pump, no matter what operating state the internal combustion engine is in.

Furthermore, since the target value of the tilting amount of the swash plate is determined from the discharge pressure P of the hydraulic pump together with the rotational speed deviation signal ΔN, stable control can be performed in response to changes in the discharge pressure P.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of a drive system for an internal combustion engine and a liquid pump according to an embodiment of the control device of the present invention, and FIG. 2 shows a configuration of a fuel injection pump and rack drive means of the internal combustion engine shown in FIG. 1. System diagram, FIG. 3 is a system diagram showing the configuration of the swash plate operating mechanism of the hydraulic pump shown in FIG. 1, FIG. 4 is a flowchart explaining the operation of the internal combustion engine control device, and FIG. Characteristic diagram showing the relationship between deviation and rack displacement command value, No. 6
The figure is a characteristic diagram showing an example of the relationship between the internal combustion engine rotation speed and the maximum engine rotation speed deviation of the rack displacement command value and the hydraulic pump input torque. FIG. 10 is a characteristic diagram showing the relationship between the amount of swash plate tilting and the command value, and FIG. 11
The figure is an explanatory diagram for explaining the method of parallelly moving the line diagram shown in Figure 10, Figure 12 is a characteristic diagram showing the relationship between rotation speed deviation and circuit pressure correction value, and Figure 13 is rotation speed deviation. FIG. 14 is a flowchart illustrating the operation for determining the swash plate tilt amount command value based on the input torque control function, and FIG. A characteristic diagram showing a control function used to regulate the maximum value of the circuit pressure, and FIG. 16 is a flowchart explaining the control operation of the swash plate operating mechanism. 1... Internal combustion engine, 2, 3...
...Hydraulic pump, 4.5... Swash plate operation mechanism, 6... Fuel injection pump, 7...
...Made by throttle lever fi! Detector, 8.
9......Operation゛lever operation amount detector, I
O...Output rotation speed detector, 11...
・・・・・・Rack position detector, 12・・・・・・・・・
Internal combustion engine control device, 13... Hydraulic pump control device. Figure 32 Figure 4 Mmax 1 I ■ Figure 5 Figure 8 Figure 9 Figure 7 Figure 0 Figure 11 Figure 12 Figure 8 N0 ΔNmax ΔN Figure 13 ΔN0 ΔNmax ΔN Figure 4 Figure 15 Pc .

Claims (1)

[Claims] Setting a target rotation speed of the internal combustion engine for a drive system including an internal combustion engine controlled by adjusting the fuel injection amount of the fuel injection pump and at least one variable displacement hydraulic pump driven by the internal combustion engine. an operating device that generates a target rotational speed signal corresponding to the target rotational speed signal; a rotational speed detection device that detects the output rotational speed of the internal combustion engine and generates an output rotational speed signal corresponding to the output rotational speed signal; a calculation device that calculates a rotation speed deviation signal that is a difference between the rotation speed deviation signal and the rotation speed deviation signal; and when the rotation speed deviation signal exceeds a predetermined set value, the input torque of the hydraulic pump is reduced as the rotation speed deviation signal increases. In a control device for a drive system including an internal combustion engine and a hydraulic pump, the input torque reducing means controls the fuel injection pump according to an increase based on the same rotational speed deviation signal used by the input torque reducing means. A first function that increases the target rack displacement amount and suppresses an increase in the target rack displacement amount when the rotation speed deviation signal reaches another set value near the maximum fuel injection amount that is slightly larger than the set value. and a fuel injection amount control device that controls the fuel injection amount by adjusting the rack position of the fuel injection pump according to the target rack displacement amount retrieved from the storage portion, and the input torque reducing means. , a pressure detection device that detects the discharge pressure of the hydraulic pump and generates a pressure signal corresponding thereto; and a predetermined input torque for the pressure signal for each rotational speed deviation signal exceeding the predetermined set value. A second tilting amount target value that is set as a value is stored.
and a swash plate tilt angle control device that controls the swash plate tilt angle of the hydraulic pump based on the tilt amount target value retrieved from the second storage unit. A drive system control device that includes an internal combustion engine and a hydraulic pump.