JP2534655B2 - Drive device for system including prime mover and hydraulic pump - Google Patents

Description

The present invention relates to a prime mover that controls the discharge amount of a variable displacement hydraulic pump driven by a prime mover with a solenoid valve by detecting a tilt angle and pressure. The present invention relates to a drive device of a system including a hydraulic pump.

<Prior Art> As a drive device for a system including a prime mover and a hydraulic pump of this type, a conventional drive device is disclosed in JP-A-57-65822.
The publication described in the issue) is known. This drive device obtains a rotational speed deviation, which is the difference between the target rotational speed set by the accelerator amount of the engine and the output rotational speed (actual rotational speed), and the hydraulic pressure increases as the rotational speed deviation increases. To reduce the input torque to the pump, calculate the target value of the swash plate tilt amount of the hydraulic pump from the rotational speed deviation and the discharge pressure of the hydraulic pump of your own, and input horsepower control based on this calculation result. Is to do. That is, by controlling the input horsepower of the hydraulic pump driven by the engine based on the deviation of the engine speed,
The deviation of the rotation speed is controlled so as to converge to zero, and the engine is always rotated at the target rotation speed so that the output can be effectively utilized. Such a control system of the input horsepower of the hydraulic pump is called a speed sensing horsepower control system.

<Problems to be Solved by the Invention> In the conventional drive device adopting such a speed sensing horsepower control method, since the input horsepower control of the pump is performed according to the discharge pressure of the pump, work having a large inertial body When driving an actuator for operating this inertial body in a machine, etc., the control system cannot fully respond to changes in pump input torque due to fluctuations in pump discharge pressure that occur when the actuator is driven, causing hunting in the control system. There is a problem that it is easy. Explaining this point in detail, in order to improve the control accuracy of the speed sensing horsepower control method in which the input horsepower of the hydraulic pump is controlled by the engine speed deviation, the control gain of the speed sensing horsepower control is made as large as possible (ΔN described later).
Taking the example of Figure 4 showing the relationship between [delta] _N, in the fourth diagram of change of ΔN a change rate of the pump input speed control value [delta] _N is increased to relative inclination i.e. the deviation ΔN of the graph [delta] _N
Must be set so that it changes as sensitively as possible). However, when the control gain is increased in this way, the set value of the input torque of the hydraulic pump changes significantly with respect to the fluctuation of the engine speed, which causes the output torque of the engine to change rapidly. The whole system becomes oscillatory. Such a phenomenon is particularly remarkable when the actuator having a large inertial body is started or when the driving speed thereof is changed, and causes a so-called hunting phenomenon. For this reason, in the conventional drive device adopting the speed sensing horsepower control system, the control gain of the horsepower control is lowered to adjust so as not to cause hunting (see FIG. 4 described later as an example. For example, if the inclination of the graph in FIG. 4 is reduced, the pump input speed control value δ _{N with} respect to the deviation ΔN
There is then less change rate [delta] _N to the change of ΔN is set to be insensitive to) necessary, Then, since the control accuracy is deteriorated and can not be effectively utilized engine output. That is, if the control gain is lowered in this way,
Since the control to converge the engine speed deviation to zero in order to effectively utilize the engine output cannot be performed accurately, especially when the maximum output of the engine is utilized, the input torque of the hydraulic pump should be adjusted to match this maximum output. Cannot be set, and the engine output cannot be fully utilized.

In addition to the drawbacks described above, the conventional drive apparatus may not be adaptable to different working conditions because it can perform only one type of input horsepower control method for the hydraulic pump.

The present invention has been made by paying attention to the drawbacks of the conventional techniques, and an object thereof is to provide a drive device of a system including a prime mover for driving a plurality of variable displacement hydraulic pumps by one prime mover and a hydraulic pump. Even if the control gain of speed sensing horsepower control is adjusted to prevent hunting, it is possible to provide a drive device that can fully utilize the prime mover output compared to the conventional technology that independently adopts the speed sensing horsepower control method. is there.

<Means for Solving Problems> In order to achieve these objects, the present invention provides a control device including a microcomputer for controlling input horsepower of a first variable displacement hydraulic pump and a second variable displacement hydraulic pump. A first calculation means for obtaining a pump input rotation speed control value from a deviation between a target rotation speed of the prime mover and an actual rotation speed, a pump input rotation speed control value obtained by the first calculation means, and a second calculation means.
Determining the first pump input control value for the first variable displacement hydraulic pump from the discharge pressure of the variable displacement hydraulic pump, and determining the second pump input rotation speed control value and the second variable displacement hydraulic pump from the discharge pressure of the first variable displacement hydraulic pump. Second computing means for obtaining a second pump input control value for the variable displacement hydraulic pump, and a first variable displacement hydraulic pump based on the first pump input control value obtained by the second computing means. And a third computing means for determining a second pump input torque related to the second variable displacement hydraulic pump on the basis of the second pump input control value. The target discharge amount of the first variable displacement hydraulic pump is obtained from the pump input torque including the first pump input torque obtained by the calculation means and the discharge pressure of the first variable displacement hydraulic pump, and the second discharge amount is calculated. And a pump input torque and discharge pressure of the second variable displacement hydraulic pump including a pump input torque second
And a fourth calculating means for obtaining a target discharge amount of the variable displacement hydraulic pump, and an instruction means for instructing to selectively perform the calculation performed by these calculating means is provided. Then, the first computing means, the second
The second calculation by setting the pump input speed control value to be calculated by the first calculation means and the calculation performed by the third calculation means, the third calculation means, and the fourth calculation means to a predetermined constant value. Means, the arithmetic operations performed by the third arithmetic means and the fourth arithmetic means, and the first pump input torque and the second pump input torque to be obtained by the third arithmetic means are set to equal constant values given in advance. And at least one of the calculations performed by the fourth calculation means can be selectively performed.

<Operation> The present invention is configured as described above, and in accordance with the deviation between the target rotational speed of the prime mover and the actual rotational speed and the discharge pressure of a variable displacement hydraulic pump other than its own variable displacement hydraulic pump,
Since it is possible to control the input horsepower of the variable displacement hydraulic pump of its own, the rotation that controls the input horsepower of the hydraulic pump according to the deviation of the number of lines of the prime mover according to the instruction of the instruction device. Number detection type total horsepower control, hydraulic detection type total horsepower control that controls the input horsepower of the hydraulic pump so as not to exceed the output of the prime mover, and the discharge of each hydraulic pump so that the hydraulic pump has a pre-assigned output The individual control system horsepower control or the like for obtaining the discharge amount from the pressure can be selectively implemented.

<Example> Hereinafter, a drive device of a system including a prime mover and a hydraulic pump of the present invention will be described with reference to the drawings.

FIG. 1 is a circuit diagram showing the overall configuration of an embodiment of the present invention,
FIG. 2 is an explanatory diagram showing the configuration of the control device provided in the embodiment shown in FIG.

In FIG. 1, 1,1 'are the first and second variable displacement hydraulic pumps, 2,2' are variable displacement volume mechanisms of the variable displacement hydraulic pumps 1,1 ', and 3,3' are variable displacement volumes. Mechanism 2,
Servo pistons driving 2 ', 4, 4'servo pistons
Servo cylinder for storing 3,3 '. 4a, 4a ′ and
Reference numerals 4b and 4b 'denote the left and right chambers of the servo cylinders 4 and 4'divided by the servo pistons 3 and 3'. The cross-sectional areas D of the left chambers 4a and 4a 'are the right chambers 4b and 4b, respectively. It is formed larger than the sectional area d of ′. 5 is a servo cylinder 4,
An oil pressure source for supplying pressure oil to 4 ', and an oil tank 6 for storing hydraulic oil in this circuit.

7,7 'are hydraulic power source 5 and left chambers 4a, 4 of servo cylinders 4,4'
a'for connecting the hydraulic pressure source 5 and the right side chambers 4b, 4b 'of the servo cylinders 4, 4', 9,
Reference numeral 9'is a return conduit for connecting the conduits 7,7 'and the oil tank 6, 10,10' is a solenoid valve interposed between the hydraulic power source 5 and the conduits 7,7 ', 11,11 Reference numeral ′ is a solenoid valve provided between the pipelines 7 and 7 ′ and the return pipelines 9 and 9 ′. These solenoid valves 10, 10 ', 11,
11 'is a normally closed solenoid valve (function to return to the closed state when de-energized). 12, 12 'in displacement meter, a variable displacement hydraulic pump 1, 1' displacement of the variable mechanism 2, 2 'detects the displacement of the discharge quantity signal Q _p in proportion to the amount of displacement, Q _p' and outputs the . Reference numerals 13 and 13 'are discharge pipes of the variable displacement hydraulic pumps 1 and 1'.

16,16 'is the discharge pipe line 13,1 of the variable displacement hydraulic pump 1,1'
A pressure detector provided at 3'detects the pressure of the pressure oil discharged from the variable displacement hydraulic pumps 1,1 ', and outputs electric signals, that is, discharge pressure signals P, P'. 17, 17 'is variable displacement hydraulic pump 1, 1' shall apply in the command device for changing the displacement of the target discharge quantity signal Q _r, and outputs a Q _r '. 1
4 is a prime mover, and 20 is a rotation speed detector for detecting the rotation speed of the prime mover 14.

Reference numeral 18 is a control device composed of a microcomputer.
As shown in the figure, the central processing unit 18a and the output I / O
Output from the interface 18b, the amplifiers 18c, 18d, 18e, 18f connected to the solenoid valves 10, 10, 10 ', 11', the memory 18h for storing the control procedure program, and the displacement gauges 12, 12 '. Discharge amount signals Q _p , P _p ′, discharge pressure signals P, P ′ output from pressure detectors 16 and 16 ′, and target discharge amount signals Q _r and Q output from command devices 17 and 17 ′. Convert _r ′ to digital signal A
The / D converter 18g and a counter 18j that detects a pulse corresponding to the rotation speed output from the rotation speed detector 20 and measures the interval of the pulse are provided.

Next, the control method for the drive device of the present embodiment will be specifically described. The greatest feature of the drive device of the present embodiment is that the control device 18 is provided with its own calculation means described later,
By introducing the concept of the cross-sensing horsepower control method to the speed sensing horsepower control method described above, the output of the prime mover 14 should be fully utilized even if the control gain of the speed sensing horsepower control is adjusted to prevent hunting. The point is that it was devised to implement a new control method that enables In short, the cross-sensing horsepower control system can utilize the surplus horsepower of the prime mover generated by the existence of the light load hydraulic pump to drive the other heavy load hydraulic pumps when driving multiple hydraulic pumps with one prime mover. It is a control method for controlling as described above. The present invention applies the concept of this cross-sensing horsepower control method to distribute the increments of the pump input torque obtained as a result of the speed-sensing horsepower control. In order to implement such a control method of the present invention, in the present embodiment, a change in the load of one hydraulic pump is detected using the discharge pressure of that hydraulic pump, and the input torque of the other hydraulic pump is detected based on the detection result. I am trying to reduce. The above points are directly expressed in the equations (5) and (7) described later.

In describing the control method according to the present embodiment, basic terms will be briefly described in advance so that the features can be easily understood.

Pump input speed control value δ _N Increment of pump input torque obtained from deviation ΔN between target speed N _O and actual speed Ne in speed sensing horsepower control, that is, minimum input torque setting of variable displacement hydraulic pumps 1, 1 ′ The pump input torque added to the values T _MIN and T _MIN ′. This pump input speed control value δ
_N is obtained from the relationship illustrated in FIG. 4, in other words, the relationship represented by the equations (2) to (4) described below.

Pump input control value δ, δ'Increment of pump input torque obtained by speed sensing horsepower control and cross-sensing horsepower control, that is, minimum input torque set value of variable displacement hydraulic pump 1, 1 '
Pump input torque added to T _MIN and T _MIN ′. In other words, it is the sum of the pump input torque increment generated as a result of the cross-sensing horsepower control and the pump input speed control value δ _N. The pump input control values δ and δ ′ are obtained from the relationship illustrated in FIG. 5, in other words, the relationship expressed by the equations (5), (6) or (7), (8) described later. .

Therefore, to describe the control system according to the present embodiment, the memory 18h and the central processing unit 18a described above,
First computing means for obtaining a pump input rotational speed control value δ _N from the deviation between the target rotational speed N _O of the prime mover 14 and the actual rotational speed N _e ;
From the pump input speed control value including the pump input speed control value δ _N obtained by the first computing means and the discharge pressure signal P ′ of the second variable capacity hydraulic pump 1 ′, the first variable capacity hydraulic pump The first pump input control value δ related to the first variable displacement hydraulic pump 1 ′ is calculated from the above-described pump input rotation speed control value and the discharge pressure signal P of the first variable displacement hydraulic pump 1. The second computing means for obtaining the second pump input control value δ ′ and the first variable displacement hydraulic pump 1 based on the first pump input control value δ obtained by the second computing means. Of the second variable displacement hydraulic pump 1'based on the second pump input control value δ'obtained by the second calculation means. Third calculation means to be obtained and this third calculation With obtaining the target discharge amount Q _ps from the first pump input torque includes a pump input torque T of the first discharge pressure signal P of the variable displacement hydraulic pump 1 obtained first variable displacement hydraulic pump stage, From the pump input torque including the above second pump input torque T ′ and the discharge pressure signal P ′ of the second variable displacement hydraulic pump 1 ′, the second
Of the variable displacement hydraulic pump 1 ', a fourth calculating means for obtaining the target discharge amount _Q'ps of the variable displacement hydraulic pump 1', a fifth calculating means for setting the pump input speed control value δ _N to a constant value, and a pump input torque T,
And a sixth arithmetic means for setting T'to a constant value.

Reference numeral 30 shown in FIG. 1 is connected to the control device 18, and any one of a plurality of pump input horsepower control modes, for example, a rotational speed detection type horsepower control, a hydraulic pressure detection type total horsepower control, and an individual control type horsepower control. It is an instruction means for selectively instructing one, for example, a dial type switch that can be manually operated by an operator. This switch 30 is, for example, SW1, SW2, SW3
There are three designated positions, and when the designated position SW1 is designated, the rotational speed detection type total horsepower control is performed as described below, and when the designated position WS2 is designated, the hydraulic pressure detection type total horsepower control is performed. The individual control system horsepower control is performed when the designated position SW3 is designated.

Then, the control device 18 described above appropriately outputs the discharge amount signals Q _p and Q ′ _p from the displacement gauges 12 and 12 ′ and the pressure detectors 16 and 16 ′ in response to the instruction from the switch 30. The discharge pressure signals P, P ', the target discharge amount signals Q _r , Q' _r output from the command devices 17, 17 ', and the pulse intervals detected by the rotation speed detector 20 are counted by the counter 18j. Based on the rotational speed N _e obtained by measurement, the variable displacement hydraulic pump 1,1 ′ based on a control procedure program described later stored in the memory 18h.
Drive command value is calculated and the command signals Q _O and Q ′ _O are _output to the solenoid valve.
Servo pistons so that the discharge amount signals Q _p , Q ′ _p , which are the outputs of the displacement gauges 12, 12 ′, are output to 10, 10 ′, 11, 11 ′ and are equal to the command signals Q _O , Q ′ _O. The 3 and 3'positions are controlled by an on-off servo using an electro-hydraulic servo.

In the on / off servo, when the solenoid valves 10 and 10 'are excited to switch to the switching position B, the left chambers 4a and 4a' of the servo cylinders 4 and 4'communicate with the hydraulic power source 5 and the left chambers 4a and 4a '. And the right side chambers 4b and 4b 'are different in area, the servo pistons 3 and 3'are the first
Move to the right on the figure. When the solenoid valves 10 and 10 'and the solenoid valves 11 and 11' are demagnetized and returned to the switching position A, the oil passages in the left side chambers 4a and 4a 'are broken and the servo pistons 3 and 3'are disconnected.
Is held stationary at that position. Also, solenoid valve 1
When 1,11 'is excited and switched to the switching position B, the left side chamber 4
a, 4a 'and the oil tank 6 communicate with each other, the pressure in the left side chambers 4a, 4a' decreases, and the servo pistons 3, 3'are moved to the left side in FIG. 1 by the pressure in the right side chambers 4b, 4b '. Moving.

Next, a control procedure performed by the control device 18 of the embodiment configured as described above will be described with reference to FIG.

First, in step 111, the state quantity is read into the central processing unit 18a, that is, the discharge pressure signal P of the pressure detector 16, the discharge pressure signal P'of the pressure detector 16 ', and the discharge amount signal of the displacement gauge 12.
Counter according to Q _p , displacement meter 12 ′ discharge amount signal Q ′ _p , command device 17 target discharge amount signal Q _r , command device 17 ′ target discharge amount signal Q ′ _r and rotation speed detector 20 signal The rotation speed N _e of the prime mover 14 obtained at 18j is read.

Next, the procedure proceeds to step 112, where it is judged which of the designated positions is output from the switch 30, and the designated position is switched to the SW.
If it is determined to be 1, the process proceeds to step 113.

In step 113, ΔN = N _e −N _o (1) is calculated in the first calculation means from the read rotational speed N _e and the preset target rotational speed N _o (for example, the rated rotational speed of the prime mover 14). ) Is performed, and from ΔN obtained by the equation (1), a pump input rotation speed control value δ _N = f (ΔN) is calculated. FIG. 4 is an explanatory diagram showing an example of the functional relationship of δ _N = f (ΔN), and is expressed as follows when expressed by an equation.

When ΔN <−ΔN ₁ δ _N = 0 (2) −ΔN ₁ ≦ ΔN ≦ ΔN ₂ δ _N = α · ΔN + δ _NO (3) When ΔN> ΔN ₂ δ _N = δ _N2 (4) Next, the procedure proceeds to step 114, and the pump input speed control value δ _N obtained by the above-mentioned first calculating means and the second variable displacement hydraulic pump 1 From the discharge pressure signals P and P ′ of 1 and 1 ′, the first pump input control value δ = g in the second calculation means.
(P ′, δ _N ), second pump input control value δ ′ = g (P,
An operation for obtaining δ _N ) is performed. FIG. 5 is an explanatory diagram showing an example of these functional relationships, and is expressed as follows when expressed by an equation.

When P ≦ P ₁ δ = −β · P ′ + δ ₁ + δ _N (5) [where β = δ ₁ / P ₁ , δ ₁ and P ₁ are constants] When P> P ₁ δ = δ _N (6 ) Similarly, when P ′ ≦ P ₁ ′, δ ′ = − β ′ · P + δ ₁ ′ + δ
_N (7) [where β ′ = δ ₁ ′ / P ₁ ′, δ ₁ ′ and P ₁ ′ are constants] When P ′> P ₁ ′, δ ′ = δ _N (8) (-Β · P '+ in (5)
δ ₁ ) and (-β ′ · P ′ + δ ₁ ′) in the equation (7) are
In the cross-sensing horsepower control, the pump input torque increment obtained from the partner pump discharge pressure P'or P,
That is, it is an increment of the pump input torque added to the minimum input torques T _MIN and T _MIN ′ preset by the variable displacement hydraulic pumps 1 and 1 ′, and δ _N is, as described above, speed sensing. It is an increment of pump input torque due to horsepower control. The sum of the pump input torque increments due to the cross-sensing horsepower control and the pump input torque increments due to the speed sensing horsepower control δ, δ ′
Is a basic numerical value for obtaining the torque of the variable displacement hydraulic pump 1, 1'as shown in the following equations (9) and (11).

Next, the procedure proceeds to step 115, and the third computing means performs the following processing. That is, the preset minimum input torque T _{min of} the first variable displacement hydraulic pump 1 and the first pump input control value δ obtained by the second calculating means described above.
From the above, the first pump input torque T relating to the first variable displacement hydraulic pump 1 is obtained as follows.

T = T _min + δ (9) Similarly, with respect to the second variable displacement hydraulic pump 1 ′, similarly, the minimum input torque T ′ _min set in advance and the second pump input control value δ ′ described above Pump input torque T'is determined as follows.

T '= T' _min + δ '(10) Next, the procedure proceeds to step 116, and the following processing is performed by the fourth computing means. That is, from the discharge pressure signal P of the first variable displacement hydraulic pump 1 and the first pump input torque T of the equation (9), the target discharge amount _{Qps of} the first variable displacement hydraulic pump 1 is as follows. Required to.

Q _ps = T / P (11) Similarly for the second variable displacement hydraulic pump 1 '
Of the variable displacement hydraulic pump 1'of
From the second pump input torque T'of the equation (0), the target discharge amount _{Q'ps of} the second variable displacement hydraulic pump _1'is obtained as _follows .

_Q'ps = T '/ P' (12) In this case, although the equations (11) and (12) may be divided as they are, the division usually takes a long calculation time. It is also possible to take an objective method.

That is, as shown in FIG. 6, for example, a reference hyperbola f _o (P) = 1 / P is stored in the memory 18h in advance, and the value of this hyperbola is calculated from the discharge pressure signal P = Pa, for example.
f _o (Pa) is read from the memory 18h and multiplied in the form of Q _ps = f _o (Pa) × (T _min + δ) (13) for calculation. In this way, the calculation time becomes short.

As another method, a hyperbola of Q _ps = T _min / P (14) is stored in the memory 18h and Q corresponding to δ
It is also possible to convert the coordinate axes of _ps and P to obtain an approximate value of Q _ps .

After the calculation by the first, second, third, and fourth calculation means is performed as described above, the procedure proceeds to step 117.

In this procedure 117, and selects the minimum value of the target discharge quantity signal Q _r of the first variable displacement hydraulic pump 1 of the target discharge amount Q _ps and the command device 17 obtained in step 116, which command signal Q _o age,
Select the minimum value of _r 'target discharge quantity signal Q' of the second variable displacement hydraulic pump 1 _ps and the command device 'target discharge amount Q of' 17, processing is performed to do this the command signal Q _'o .

Next, at step 118, the discharge amount of the first variable displacement hydraulic pump 1 and the discharge amount of the second variable displacement hydraulic pump 1'are controlled using _Qo and _Q'o as target values.

In this control, the number of revolutions of the prime mover 14 is detected, and the discharge pressure and discharge amount of other variable displacement hydraulic pumps and the discharge pressure and discharge amount of its own variable displacement hydraulic pump Since the discharge rate of the pump is controlled, it is possible to implement a total horsepower control with a rotation speed detection method that provides stable performance.This method is used when performing work that makes full use of horsepower, such as digging in a hydraulic shovel. It is suitable when performing heavy excavation work.

That is, in this control, the torque T considering the first pump input torque δ and the discharge pressure signal P of the first variable displacement hydraulic pump 1 are calculated by the third calculating means and the fourth calculating means. seeking by connexion first variable displacement hydraulic target discharge amount Q _ps pump 1, and 'torque T in consideration of the' second pump input torque [delta], the discharge pressure signal P of the second variable displacement hydraulic pump 1 ' Since the target discharge amount Q'ps of the second variable displacement hydraulic pump _1'is obtained from the above, the first variable displacement hydraulic pump 1 and the second variable displacement hydraulic pump 1'are different from each other. Can obtain independent discharge amounts.

Further, the second calculation means obtains the first pump input control value δ for the first variable displacement hydraulic pump 1 from the discharge pressure signal P ′ of the second variable displacement hydraulic pump 1 ′, and the first variable Since the second pump input control value δ ′ relating to the second variable displacement hydraulic pump 1 ′ is obtained from the discharge pressure signal P of the displacement hydraulic pump 1, the input torque of the other pump can be compared with the input torque of the other pump. Can be increased or decreased so that the total input torque is within the output range of the prime mover 14.

Further, based on the pump input rotational speed control value δ _N obtained by the first calculation means, the second calculation means calculates the first pump input control value δ for the first variable displacement hydraulic pump 1, Since the second pump input control value δ ′ for the variable displacement hydraulic pump 1 ′ is obtained, the total input torque can be controlled according to the output of the prime mover 14.

In this embodiment, the first computing means, the second computing means, and the third computing means are adopted to introduce the concept of the cross-sensing horsepower control method into the speed sensing horsepower control method. The control gain of the horsepower control (change rate of δ _N with respect to ΔN) is
Even if the adjustment is made so that hunting does not occur, the output of the prime mover 14 can be fully utilized, unlike the conventional technology in which the speed sensing horsepower control system is independently adopted. Therefore, the reason for this will be described while explaining the characteristic phenomenon that occurs when the speed sensing horsepower control method and the cross sensing horsepower control method are individually adopted.

As described above, in the speed sensing horsepower control system of the present embodiment, the pump input torque is calculated from the deviation ΔN (actual speed Ne−target speed N _O ) between the target speed and the actual speed of the prime mover 14. The input torque of 1,1 ′ of the variable displacement hydraulic pump is controlled by obtaining the incremental pump input speed control value δ _N. The deviation ΔN and the rotation speed of the prime mover 14 which is the basis for calculating the deviation ΔN are The signal is a signal that changes slowly with respect to a change in pump input torque due to the influence of the flywheel inertia of the prime mover 14 itself. By the way, in order to perform accurate control by this speed sensing horsepower control method, the pump input speed control value δ _{N is} calculated from the deviation ΔN.
It is necessary to set a large coefficient for obtaining the control gain, that is, if the control gain is set to a large value, even if the deviation ΔN is the same, the change in the pump input torque caused by the control with the deviation ΔN becomes large. For example, regarding the case where the pump input torque increases as a result of the control with the deviation ΔN, the rotation speed of the prime mover 14 and the deviation ΔN are signals that change slowly with respect to the change of the pump input torque as described above. Therefore, the change of the rotation speed of the prime mover 14 with respect to the increase of the pump input torque occurs with a delay, the degree of the change becomes large, and the rotation speed of the prime mover 14 tries to decrease more than necessary. In such a case, it is necessary to reduce the torque applied to the prime mover 14 by reducing the pump input torque, but since the change in the rotation speed of the prime mover 14 occurs with such a delay, the timing of reducing the torque is After that, the decrease in the rotation speed of the prime mover 14 becomes large. On the contrary, when the pump input torque decreases as a result of the control with the deviation ΔN, the pump input torque decreases excessively, and the rotation speed of the prime mover 14 exceeds. In the speed-sensing horsepower control method, by repeating such actions, low-cycle hunting occurs in the prime mover / pump system. Therefore, when the speed sensing horsepower control method is independently adopted, it is not possible to control using a large control gain, and as described above, the output of the prime mover 14 cannot be fully utilized.

The characteristic phenomenon that occurs when the cross-sensing horsepower control system is adopted will be described. The cross-sensing horsepower control system of this embodiment changes the load (change of input torque) of the counterpart hydraulic pump to the discharge pressure of the pump. The pump input torque is detected based on the detection result. The signal relating to the discharge pressure of the hydraulic pump is the deviation ΔN described above.
Unlike the motor and the rotation speed of the prime mover 14, the signal is a signal that changes rapidly in response to changes in the load of the hydraulic pump. The cross-sensing horsepower control method controls the pump input torque using a signal that changes rapidly in response to such load fluctuations, so it controls its own pump input torque with a quick response to the load fluctuations of the partner hydraulic pump. It is possible to prevent the prime mover 14 from being overloaded.

However, in this embodiment, when the pump input speed control value δ _N , which is the increment of the pump input torque obtained by the speed sensing horsepower control method, is processed, (5),
Since the concept of the cross-sensing horsepower control method is introduced as shown in the equation (7), the speed-sensing horsepower control method can be used even if the control gain of the speed-sensing horsepower control is adjusted so that hunting does not occur. The control gain can be increased as compared to the case where it is used alone, and the output of the prime mover 14 can be fully utilized. That is,
When the speed sensing horsepower control system and the cross sensing horsepower control system are combined in this manner, the above-described prime mover generated by the speed sensing horsepower control system is generated.
The problem of the delay in the change in the rotational speed of 14 can be corrected in advance by the cross-sensing horsepower control method. For example, the first
Assuming a case where the load of the second variable displacement pump 2 ′ increases and the load applied to the prime mover 14 increases while the variable displacement pump 2 and the second variable displacement pump 2 ′ of FIG. Although the rotation speed decreases due to the increase in the load, the cross-sensing horsepower control causes the pump input torque of the first variable displacement pump 2 to be decreased in advance in a quick response during the decrease process, so that the prime mover 14 is not overloaded. However, it is possible to prevent the rotation speed of the prime mover 14 from dropping as in the case where the speed sensing horsepower control system is independently adopted. Therefore, the control gain of the speed sensing horsepower control can be stabilized even if the control gain is increased as compared with the case where the horsepower control is independently adopted, so that accurate control can be performed and the output of the prime mover 14 is sufficiently high. Can be used for. In other words, in order to prevent hunting, even if the control gain of the speed sensing horsepower control is adjusted to a stable value so that the control system does not oscillate, it is different from the conventional technology that independently adopted the speed sensing horsepower control method. , The output of the prime mover 14 can be fully utilized.

As described above, the present invention provides the concept of the cross-sensing horsepower control method by the speed-sensing horsepower control method for the purpose of fully utilizing the prime mover output even if the control gain is adjusted to prevent hunting. The present invention is applied to the processing of the pump input rotational speed control value δ _N , which is the increment of the pump input torque, and the idea is novel.

Further, the functional relationships utilized in the first computing means and the second computing means are not limited to the linear functional relationships shown in FIG. 4 and FIG. 5, and can be easily changed as necessary, It is possible to obtain desired characteristics without changing or adjusting other components other than the control device 18.

Further, in step 112 shown in FIG. 3, when it is determined that the indicated position output from the switch 30 is SW2, the process proceeds to step 119, and the operation in the fifth operation means, that is, δ _N = D (15 ) [Where D is a constant given in advance], and then the above-mentioned steps 114, 115,
116, 117, 118 are carried out.

In this control, the pump input speed control value δ _N is set to a constant value D in advance so that the sum of the outputs of the variable displacement hydraulic pumps 1, 1 ′ does not exceed the output of the prime mover 14. It is possible to perform full horsepower control with the oil pressure detection method. In this method, the horsepower corresponding to the output of the prime mover 14 cannot be obtained, but since the rotation speed of the prime mover 14 is not detected, stable horsepower control without a sudden change in the rotation speed can be obtained, and It is possible to perform horsepower control so that the total output of the variable displacement hydraulic pumps 1 and 1'does not exceed a given value. For example, in a town where it is not desirable that the rotational noise of the prime mover 14 changes. Suitable for light work etc.

Further, in step 112 shown in FIG. 3, when it is determined that the designated position output from the switch 30 is SW3, the process proceeds to step 120, and the operation in the sixth operation means, that is, T = T '= K (16) Then, the procedure proceeds to step 116, and the target discharge amount Q _ps of the first variable displacement hydraulic pump 1 and the second variable displacement are obtained by the input torque T, T ′ of the pump obtained by the equation (16). is required _ps 'target discharge amount Q of the' displacement hydraulic pump 1, steps 117 and 118 are implemented following.

For this control, each variable displacement hydraulic pump
The individual control system horsepower control for controlling the input horsepower can be performed based on the input horsepower constant K given to 1,1 'and the respective discharge pressure signals P, P'.

In this method, work that does not want its own discharge rate to change with the discharge pressure of another variable displacement hydraulic pump, that is, work that does not require a large amount of horsepower but does not like speed changes, such as hydraulic pressure It is suitable for slope excavation work carried out at Sjobel.

<Effects of the Invention> As is apparent from the above description, the "driving device for the system including the prime mover and the hydraulic pump" of the present invention introduces the concept of the cross-sensing horsepower control method into the speed sensing horsepower control method and claims the invention. By embodying as described in the range, even if the control gain of the speed sensing horsepower control is made larger than that when the horsepower control is independently adopted, the control can be stabilized and accurate control can be performed. It will be possible. Therefore, according to the present invention, the control gain of the speed sensing horsepower control is adjusted so as to prevent hunting in a drive device of a system including a prime mover and a hydraulic pump that drives a plurality of variable displacement hydraulic pumps with one prime mover. Even so, it is possible to obtain a novel drive device that can fully utilize the output of the prime mover as compared with the conventional technology in which the speed sensing horsepower control system is independently adopted.

Further, by providing an instruction means for instructing to selectively perform various operations performed by the first arithmetic means, the second arithmetic means, the third arithmetic means and the fourth arithmetic means, these already deployed It is possible to effectively switch the control system of the input horsepower of the hydraulic pump to a plurality of types by effectively utilizing the calculation means of, and it is possible to adapt to different working conditions.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit diagram showing the overall configuration of an embodiment of a drive device for a system including a prime mover and a hydraulic pump of the present invention, and FIG. 2 is provided for the embodiment shown in FIG. FIG. 3 is an explanatory diagram showing the configuration of the control device, FIG. 3 is a flowchart showing the control procedure processed by the control device shown in FIG. 2, and FIG. 4 is a rotational speed deviation and pump set by the control device shown in FIG. FIG. 5 is an explanatory view showing an example of the relationship with the input rotational speed control value, and FIG. 5 shows an example of the relationship between the discharge pressure signal of the variable displacement hydraulic pump set by the control device shown in FIG. 3 and the pump input control value. Explanatory drawing, FIG. 6 is a figure explaining the approximation method of the calculation performed by the 4th calculating means of the control apparatus shown in FIG. 1 ... First variable displacement hydraulic pump, 1 '... Second variable displacement hydraulic pump, 10,10'11,11' ... Solenoid valve, 12,12 '
...... Displacement meter, 14 ...... Motor, 16,16 '...... Pressure detector, 1
7, 17 '... Command device, 18 ... Control device, 18a ... Central processing unit, 18b ... I / O interface, 18c, 18d, 18e,
18f ... Amplifier, 18g ... A / D converter, 18h ... Memory, 18j ... Counter, 20 ... Rotation speed detector, 30 ... Switch (indicator).

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Watanabe 650 Kintatecho, Tsuchiura City, Hitachi Construction Machinery Co., Ltd.Tsuchiura Plant (72) Inventor Shigetaka Nakamura 650, Jinmachicho, Tsuchiura City, Hitachi Construction Machinery Co., Ltd. Within

Claims (1)

(57) [Claims] 1. A system including one prime mover and at least a first variable displacement hydraulic pump and a second variable displacement hydraulic pump, wherein a first variable displacement hydraulic pump and a second variable displacement hydraulic pump are provided. In a drive device having a control device composed of a microcomputer for controlling input horsepower, the control device obtains a pump input rotation speed control value from a deviation between a target rotation speed and an actual rotation speed of a prime mover,
A first pump input control value for the first variable displacement hydraulic pump is obtained from the pump input rotational speed control value obtained by the first calculation means and the discharge pressure of the second variable displacement hydraulic pump, and the pump is controlled. Second calculation means for obtaining a second pump input control value for the second variable displacement hydraulic pump from the input rotational speed control value and the discharge pressure of the first variable displacement hydraulic pump, and the second calculation means. A first pump input torque relating to the first variable displacement hydraulic pump is obtained based on the obtained first pump input control value, and a second variable displacement hydraulic pump relating to the second variable displacement hydraulic pump is determined based on the second pump input control value. Second
Of the pump input torque including the first pump input torque obtained by the third calculating means and the discharge pressure of the first variable displacement hydraulic pump. The target discharge amount of the variable displacement hydraulic pump is calculated, and the target discharge amount of the second variable displacement hydraulic pump is calculated from the pump input torque including the second pump input torque and the discharge pressure of the second variable displacement hydraulic pump. Fourth
And an instruction means for instructing to selectively perform the arithmetic operation performed by these arithmetic means. According to the instruction of the instruction means, the first arithmetic means and the second arithmetic means are provided. Means, the third arithmetic means, and the arithmetic operation performed by the fourth arithmetic means, and the pump input speed control value to be obtained by the first arithmetic means are set to a predetermined constant value, and the second arithmetic means is set. The first pump input torque and the second pump input torque to be obtained by the third computing means and the fourth computing means and the third computing means are set to a predetermined equal constant value, 4. A drive device for a system including a prime mover and a hydraulic pump, wherein at least one of the calculations performed by the calculation means of 4 is selectively performed.