JPS6065951A - Automatic neutral point detecting device of hydraulic pump - Google Patents

Abstract

PURPOSE:To automatically detect a neutral point by displacing a variable mechanism for controlling the squeeze capacity of a variable-capacity hydraulic pump in + and - directions to find a neutral point from the average of displacement of the variable mechanism when the discharge pressure of the hydraulic pump amounts to a set pressure. CONSTITUTION:A hydraulic motor 11 is rotated forward and backward by oil pressure discharged from a double swash plate variable capacity hydraulic pump 1, and the hydraulic motor 11 is braked by a bake device 15. This arrangement further includes a displacement detector 4 for detecting the displacement of a swash plate 1a and a control device 9 for detecting the neutral point of the hydraulic pump 1. The conical device 9 operates the brake device 15 according to indication of a start device 10 and displaces the swash plate 1a in + and -directions once at least until each detected pressure of pressure detectors 8a, 8b is substantially equal to a preset pressure. At this time, the displacement values of the swash plate 1a are accumulated to take an average.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic neutral point detection device for a non-hydraulic pump that automatically detects the neutral point of a hydraulic pump that drives at least one actuator. A neutral point automatic hydraulic pump equipped with a variable displacement mechanism that can be displaced in both directions, automatically operates the variable displacement mechanism to control the discharge amount and control the operation of the oilfield actuator. This invention relates to a detection device.

In recent years, in order to achieve energy saving and high functionality, hydraulic pumps used in various hydraulic machines and hydraulic devices have been equipped with a displacement displacement mechanism that can be displaced in the (+) direction and (-) direction. A device that electrically controls this displacement volume variable mechanism to adjust the discharge amount has been proposed and is in use. In such a control device, the displacement of the variable displacement mechanism of the hydraulic pump is automatically detected,
Control is performed using the signal. In this case, it is necessary to accurately match the neutral point of the hydraulic pump to the signal from the displacement detection device that detects the displacement of the variable displacement mechanism at that time. For this reason, the control device for the oil field pump has used a D point correction circuit that finds the neutral point of the hydraulic pumper and corrects the signal of the displacement detection device.

FIG. 1 is a system diagram of a hydraulic circuit and an electric circuit of a hydraulic pump control device equipped with a zero point correction circuit.

In the figure, 1 is a double tilting variable displacement hydraulic pump (hereinafter simply referred to as an oil field pump), and 1a is a variable displacement mechanism of the hydraulic pumper 1. The variable displacement mechanism 1a has a swash plate, a slant shaft, etc. depending on the type of oil field bomb f10, and in the following explanation, the swash plate will be used as a representative. 2 is a regulator that drives and operates the swash plate 1a according to an input electric signal;
Reference numeral 11 denotes a hydraulic motor driven by a hydraulic cylinder 7''1, which is used, for example, to drive a traveling body. Reference numeral 15 denotes a brake device, which is composed of a brake shoe 15a, a cylinder chamber 15b, and a spring 150. By sending pressure oil from an oil field source 16 to the cylinder chamber 15b, the spring 150 is compressed and the brake shoe 15& is released from the hydraulic motor 11, and the cylinder chamber 1
When 5'b is communicated with the tank 17, the spring 150 is extended, and the brake shoe 15a contacts the hydraulic motor 11 to apply the brake. 3 is a brake switching valve that switches the connection between the cylinder chamber 151) of the brake device 15 and the oil field source 16 and tank 17. The switching valve 3 is switched by an electric signal, and is set to the A position by the electric signal O11'F, and the brake device 1 is switched to the A position.
Activate 5 and turn it on to position B. Brake device-15
Release. A displacement detector 4 detects the displacement, that is, the amount of tilting, of the swash plate 1a, and is composed of a potentiometer or the like. The displacement detector 4 is mechanically coupled to the swash plate 1a, and outputs a signal corresponding to the amount of tilt of the swash plate 1a.

Reference numeral 5 denotes an O point correction circuit for correcting 400 points of the displacement detector, and is composed of a variable resistor 5a and an addition circuit 5b. The zero point correction and the zero point correction circuit 5 will be described later. Reference numeral 6 denotes an operating lever for operating the actuator, and outputs a signal according to the amount of operation thereof. 7 is a control device that outputs control signals to the layer generator 2 and the switching valve 3 based on the signal from the zero point correction circuit 5 and the signal from the operating lever 6;
Using this control signal, the amount of tilting of the swash plate 1a is made to match the amount of tilting instructed by the operating lever 6, and the OJ of the switching valve 3 is
Controls OFF.

Here, the zero point correction and O point correction circuits will be described.

In order to detect the amount of tilting of the swash plate 1a, the displacement detector 4 detects the neutral point of the hydraulic pumper, that is, the neutral point of the swash plate 1a, and a corresponding signal output from the displacement detector 4 at that time, for example, O
v must match. However, swash plate 1a
and the displacement detector 4 are mechanically coupled, and it is extremely difficult to couple them so that the neutral point of the swash plate and the corresponding signal (Ov) completely match. However, if there is a mismatch between the neutral point of the swash plate 1a and the signal of the displacement detector 4, the signal of the displacement detector 4 becomes the neutral point signal even though the swash plate 1a is not at the neutral point position, and the control device 7 Control is performed using the tilting position of the swash plate 1a as a neutral point, and as a result, even though the operating lever 6 is in the neutral position, in other words, the discharge amount of the hydraulic cylinder f1 is instructed to be 0. Despite this, the actual tilting position of the swash plate 1a does not reach the neutral point, and pressure oil is discharged from port a or port b of the hydraulic pump 1. In this case, since the operating lever 6 is in the neutral position, the switching valve 3 is in the A position and the brake device 15 is operating. Therefore, if the discharged pressure oil tries to drive the hydraulic motor 11 and pulls the brake device 15, or if the brake force is strong, the circuit pressure on the discharge side of the hydraulic pump 1 increases, and the pressure oil is transferred to the IJ (not shown). The oil will be released into the oil tank through the IJ valve, and the energy contained in the pressure oil will be wasted. Furthermore, even if the control lever 6 instructs the port a side and the port b side of the hydraulic pump 1 to have the same discharge amount, the actual discharge amount will be different, and even if you try to rotate the hydraulic motor 11 in one direction, A situation may occur in which the hydraulic motor momentarily rotates in the opposite direction and then rotates in the opposite direction, which has an extremely undesirable effect on the operation of the hydraulic motor.

Therefore, in the conventional device, a zero point correction circuit 5 is provided to correct the mismatch between the neutral point of the swash plate 1- and the corresponding signal from the displacement detector 4. That is, when the swash plate 1a is at the neutral point, the variable resistor 5a generates a signal corresponding to the deviation between the signal that should be output from the displacement detector 4 and the actually output happy signal, and this signal is sent to the adder circuit 5b. Correction is performed by adding it to the output signal of the displacement detector 4. Therefore, the neutral point of the swash plate 1a and the corresponding signal input to the control device 7 coincide, and the above-mentioned drawbacks are eliminated.

The amount of correction indicated by the variable resistor 5a of the zero point correction circuit 5 is set as follows. That is, first, the hydraulic pump 1 is driven by the prime mover, and the operating lever 6 is placed in the neutral position. In this state, the variable resistor 5a is adjusted so that the discharge amounts of ports a and b of the hydraulic pump 1 are both zero, that is, the swash plate 1a is at the neutral point. The value of the variable resistor 5a at this time becomes a value corresponding to the correction amount.

However, it is extremely troublesome to manually adjust the variable resistor 5a, and as the number of units increases, the trouble increases in proportion to this. It is clear that it is not desirable for such adjustments to be inserted into the manufacturing process before shipment. Furthermore, even if the product is properly adjusted and sold, discrepancies will continue to occur due to drift of the zero point correction circuit 5 due to subsequent temperature changes, aging of the joint between the swash plate 1a and the displacement detector 4, etc. Monitoring and coordination will be required, and the effort required for this will be significant.

An object of the present invention is to eliminate the above-mentioned conventional drawbacks, to automatically detect the neutral point of a hydraulic pump without manual intervention, and to enable accurate control of the hydraulic pump. The goal is to provide equipment.

To achieve this objective, the present invention, as shown in FIG. 2, includes a displacement detection device 4 and a brake device 15, as well as a pressure detection device 8 at 8 for detecting the port pressure of a hydraulic pump.
b, a start device 10 that instructs to start detecting the neutral point of the oil IIE ponzo 1, and a control device 9 that detects the neutral point of the hydraulic cylinder 7''1, and the control device 9 includes (1)
A brake actuation means 90 that instructs the operation of the brake device 15 in response to an instruction from the start device 10, and (+1) a displacement variable mechanism 1a based on information from the pressure detection devices 3a, B'b and the displacement detection device 4. to (+) direction and (
-) direction at least once each until the discharge side port pressure of the hydraulic cylinder 'f1 detected by the pressure detection devices 8a + 3b becomes at least approximately equal to the same predetermined set pressure; data collection means 91 for collecting the displacement value of the displacement variable mechanism 1a at the time when the port pressure becomes approximately equal to the set pressure;
An automatic neutral point detection device for a hydraulic pump is provided, characterized in that it is equipped with an average value means 92 for calculating the average value of the values collected by the 01D data collection means 91.

Preferably, the control device 9 further includes (iv) in response to an instruction from the start device 10, the displacement variable mechanism 1, prior to the operation of the data collection means 91 and the average value means 92.
Pump neutral means 93 for displacing a to the neutral position at that time
It is equipped with

Preferably, the control device 9 also (based on the information from the pressure detection devices sa*sb, the data collection means 91
In addition, prior to the operation of the average value means 92, an initial setting means 94 is provided which determines the initial displacement direction of the displacement volume variable mechanism 1a in the data collection means.

As shown in FIG. 3, the data collection means 91 preferably includes a port pressure determination means 910 for determining whether or not the discharge side port pressure of the hydraulic bonder 1 is greater than a set pressure;
Pump unit amount displacement means 911 displaces the displacement variable displacement mechanism 1a by a predetermined unit amount when the port pressure is not greater than the set pressure, and reads the displacement of the displacement variable displacement mechanism 1a when the port pressure becomes approximately equal to the set pressure. displacement reading means 912.

The data collecting means 91 also preferably includes a reversing means 913 for displacing the variable displacement mechanism 1a in the initial displacement direction determined by the initial setting means 94 and collecting data, and then reversing the direction of change.

The initial setting means 94 preferably includes, as shown in FIG.
a port)E force determination means 940 for determining whether or not one port pressure of the hydraulic pump 1 is greater than the set pressure when the displacement displacement variable mechanism 1a is in the neutral position;
When the E force is not greater than the set pressure, the first displacement direction is made to coincide with the direction in which the port (port) E force rises, and when the port pressure is greater than the set pressure, the first displacement direction is made to match the direction in which the port hE increases.
Displacement direction determining means 941 to match the direction in which the force decreases
and has.

The present invention will be explained below based on the embodiments shown in FIGS. 5 to 10.

FIG. 5 schematically shows an overall view of an automatic neutral point detection device for a hydraulic pump according to an embodiment of the present invention.

In Section 5@, the same or substantially the same parts as in FIGS. 1 and 2 are designated by the same reference numerals, and their explanations will be omitted. Pressure detector 8a provided on the port) asb side of the hydraulic cylinder 7''1
t8b outputs signals Pa and Pb corresponding to the pressures on the a and b sides. 9 is a control device configured using a microcomputer, and a multiluxer 9 a
, A/D converter 9bs central processing unit (hereinafter OP
It's called U. ) 90%lJ-de-only memory (hereinafter referred to as
It's called 1'tOM. )9d1 random access memory (hereinafter referred to as RAM) 9θ, an output device 9f, and an input device 9g.

The multi-pressure sensor 9a receives the signal Y from the displacement detector 4, the signal x from the explosive control lever 6, the signals Pa and P from the pressure detectors 8a and 8b.
b is switched and inputted by the control signal of OPU 9a. The A/D converter 9b receives the input analog signal x
, y, pa, 'pb into digital signals. ROM 9 (1 is a memory that stores the operating procedure of the control device 9, and OPU 9 o performs necessary calculations and control based on this operating procedure. RAM 9 e stores signals X, Y, Pa, Pb
This is a storage device that temporarily stores calculation results etc. calculated in the O'PU 90 and the O'PU 90. The output device 9f outputs a control signal obtained as a result of calculation and control to the layer generator 2 and the switching valve 3. In addition, the input device 9g is turned on by a switch 100, which will be described later.
Enter the off state. 10 is a start switch that is closed when starting detection of the neutral point of the hydraulic bonder.

Next, the operating procedure of the control device 9 stored in the RoM 9a will be explained with reference to the flowcharts shown in FIGS. 6 to 10. In this flowchart, each step is indicated by a symbol S1, S2, . . . .

In FIG. 6, the steps shown within the two-dot chain line indicate the neutral point automatic detection procedure, and the steps shown outside the two-dot chain line are normal procedures used to control the swash plate 1a. First, the normal control operation of the swash plate 1a will be explained.

When the power is turned on, the CPU 9C in the control device 9 operates the multiplexer 9a and the A/D converter 9b according to the operating procedure stored in the ROM 9d, and operates the control lever 6.
The lever command value x1, which is a signal from the displacement detector 4, the hydraulic pressure ponto displacement amount Y1, which is a signal from the displacement detector 4, and the pressures Pa and P'b, which are signals from the pressure detector 5assb, are taken in and stored in the RAM 9θ (Sl). Next, the state of the switch 10 is read from the input device 9g, and it is determined whether the switch 10 is on or off (S2).

When the switch 10 is off (when the start of neutral point automatic detection is not instructed), the 0 correction f) tYO calculated and stored by the neutral point automatic detection described later is taken out, and the pump tilting that was taken earlier is taken out. This 0 correction ff1Y from the amount Y
Calculate the corrected pump tilt My by subtracting o (
S3). Next, turn on the switching valve 3.

The OFF control is performed to control the operation of the brake device 15 (EI4), and the flow moves to a pump control servo routine (Sδ) to control the amount of tilting of the swash plate 1a to the amount instructed by the operating lever 6. FIG. 7 shows the detailed procedure of the pump control servo routine. That is, first, the new bonder tilting amount Y calculated in step 71''S3 is subtracted from the lever command value X taken in earlier, and the deviation ΔY is calculated (B
s-1). Here, it is determined whether this deviation ΔY is positive, negative, or D (S5-2), and if the deviation ΔY is positive, the swash plate 1
A signal for driving a in the (+) direction shown in FIG. 5 is output to the layer generator 2 (Bs-5). If the deviation ΔY is negative, a signal to drive the swash plate 1a in the (-) direction is output (5s-5), and if the deviation ΔY is 0, a signal to stop the swash plate 1a is output (85-4). ). When the procedure of step fS5 is completed, the procedure returns to step S1 again, and thereafter steps 81 to S5 are repeated to control the swash plate 1a.

When the start switch 10 is turned on to detect the neutral point of the hydraulic pump, an automatic neutral point detection procedure is executed. That is, when the switch 10 is turned on, the procedure shown in FIG. 6 moves from step 71'S2 to step S6, which is the neutral point automatic detection procedure within the two-dot chain line. Here, before explaining the neutral point automatic detection procedure, an outline of the procedure will be described below.

First, the oil field bong 7°1 is driven by the prime mover, and the switching valve 3 is turned OFF (position A) to operate the brake device 15. In this state, the swash plate 1a is moved in the [+] direction and (-) direction until a certain set pressure is generated.
move in the direction. Even when the brake device 15 is activated, there is a slight leakage between the ports A1 and B1 tanks in the oil field tank fl, or similarly in the motor 11, from the high pressure side to the low pressure side. There is a range in which no pressure is generated even if the plate 1a is moved.

Therefore, the movement of the swash plate 1a exceeds the above range. Whether or not the set pressure has been generated can be determined by looking at the signals Pa5Pb from the pressure detectors 8a and 8b. When the set pressure is generated, a signal Y from the displacement detector 4 is output according to the amount of tilting of the swash plate 1a at that time.

This rotation is performed each time the swash plate 1a moves in the (+) direction and (-) direction, and this reciprocation is performed multiple times. Finally, if these sampled values are totaled and the average value is calculated, this average value becomes the signal value of the displacement detector 4 corresponding to the actual neutral point of the swash plate 1eL. Then, this signal value and the signal value at the neutral point of the displacement detector 4 (i.e., the swash plate 1a
The difference between the swash plate 1a and the signal value that is to be output from the displacement detector 4 when the displacement detector 4 is at the neutral point is the deviation between the swash plate 1a and the displacement detector 4. The above is an outline of the neutral point automatic detection procedure.

This procedure will be explained in detail below. In the Stella 7's2 shown in FIG. 6, if the start switch 10 is closed, the process enters step S6 and shifts to a neutral point automatic detection procedure. First, the switching valve 3 is turned OFF and the brake device 15 is put into operation.

(S6). Next, it is determined whether or not this is the first time that the automatic neutral point detection routine has been entered (S7). This judgment is made by storing the numerical value 0 in one of the addresses of the RAM 9a when the start switch 10 is closed, and the procedure starts at step S.
This can be determined by setting the value to 1 when moving from 1 to Stella 711'S8, and checking whether the value at this address is 1 or O in Stellar S7.

In this case, since it is the first time that the neutral point automatic detection routine is entered, the procedure moves to step S8. Stetsu7°S8
Now, the Ponzo tilt command Xr, which is the drive command for the swash plate 1a.
, is neutral. This command is the same as the command after setting the operating lever 6 to the neutral position, but in this procedure, a command is issued to set the Ponzo tilting command XL to the neutral position regardless of the operating lever 6.

As a result, the lever command value X is changed to the ponno tilting command xL.
is assigned. Next, the procedure moves to step S5 in which the ponno tilt is a routine, and the process shown in FIG. 7 is performed. As a result, the swash plate 1a is displaced by the displacement detector 4.
If there is a mismatch between the neutral points of the swash plate 1a and the displacement detector 4, the swash plate 1a will tilt in the (+) direction or the (-) direction. is in a state of

The procedure returns to step B1 again, and step S2. S6
Then, the process reaches step S. Here, it is determined by looking at the contents of the address that this is the second time to enter the neutral point automatic detection routine, so the procedure moves to step S9. In step S9, it is determined that this is the second time, and the process moves to Stella 7'slQ.

At this time, the numerical value stored at the address becomes a value incremented by 1.

Step 810 is an initial setting routine, the detailed procedure of which is shown in FIG. As mentioned above, if there is a mismatch between the neutral points of the swash plate 1a and the displacement detector 4, the swash plate 1a
a is inclined in either direction, and if the inclination is severe (if the discrepancy is large), it is possible that the inclination is such that a pressure equal to or greater than the set pressure is generated. By the way, this neutral point automatic detection procedure includes a procedure of sequentially moving the swash plate 1a in the (+) direction and (-) direction, and also includes a procedure of sequentially moving the swash plate 1a in the (+) direction and (-) direction. Since the signal Y is sandaled, if the swash plate 1a is already at a tilting amount that generates a pressure higher than the set pressure, tilting in that direction is meaningless. The initial setting routine in step 810 is a routine that eliminates such meaningless tilting and first determines in which direction the swash plate 1a should be tilted. First, the signal P of the pressure detector 8a, which is taken in by the STETSU 70S1.
a The O value is the set pressure (this value is set as Pr).
It is determined whether or not the above is satisfied (S1o-1). Swash plate 1a
If the amount of tilting has not reached the point where the set pressure Pr is generated, it is effective to tilt the swash plate 1a in the (+) direction, so the tilting direction flag is set to (+) (S
:co-2). Moreover, if the signal Pa of the pressure detector 8a is already higher than the set pressure Pr, the swash plate 1a is further adjusted to (+
) direction is meaningless as mentioned above, so set the tilt direction flag to (-) (51o-3)
. This determines the initial tilting direction of the swash plate 1a in a data collection routine to be described later. Next, issue a command to set the pump tilting command hole to neutral (51o-4), and substitute this pump tilting command xL to the lever command value X (81o-5).
.

As a result, when the procedure moves to the pump tilt servo routine (s5) via the next step fS10-6, the swash plate 1
Keep the tilting of a stopped at the current position.

In STETSUNO S1o and -6, the sandal counter is cleared to 0◇In other words, as mentioned above, the swash plate 1a is reciprocated multiple times in the (+) direction and the (-) direction,
During this period, the value of the signal Y of the displacement detector 4 is collected every time the set pressure Pr is reached. This number of times of collection is set in advance, and when the set number of times of collection is reached, this collection is terminated. Therefore, it is necessary to count the number of times of collection. The sample counter is a counter used for this purpose, and the sample counter is a counter used for this purpose.
In LO-6, this counter is set to O in advance in preparation for the next collection of the value of the signal Y.

When the procedure of step 51o-a is completed, the procedure returns to step S1 again via step S5. The procedure then starts again at step 7''s1., and this time reaches step day 9 via steps fs2.s, . . . s7.

Looking at the address value at step 7°S9, this value already corresponds to the third time, so it is determined as 1 that it is not the second time, and the process moves to the next step 811. In step 811, it is determined whether the value of the sample counter mentioned above has reached the set value.

In this case, since the value of the signal Y has not yet been collected, the value of the sample counter is 0, and the process moves to the next step 7°S12.

ST7PS12 is a data collection routine. Until step 'h2 is entered, the swash plate 1a receives the pump tilting command xL.
The amount of tilting is maintained in accordance with the signal that sets the position to neutral. It is only after entering the data collection routine that the swash plate 1a is tilted in the (+) direction or (-) direction and the data (
Signal Y of displacement detector 4 when set pressure Pr occurs
) will be collected.

The detailed procedure of step fB12 is shown in FIG.

First, in step 'f812-1, step 810
Determine whether the tilting direction flag set in -2 or step 7'5IO-3 is (+] or (-). If the tilting direction flag is (+), the pressure detected by the pressure detector 8a Signal P
Determine whether a is greater than or equal to the set pressure Pr+ (B1
12-2). If the pressure signal Pa has not reached the set pressure Pr, then the pump tilting command xL is increased by 1 (B12-3). The increasing value 1 corresponds to a predetermined tilting angle of the swash plate 1a. For example, if this tilting angle is set to 5 degrees, the pump tilting command xL increases by the value 1. Tilt servo routine (Sg)
, the swash plate 1a is driven by 0.5 degrees. That is, the tilting angle of the swash plate 1a increases by 0.5 degrees until the set pressure Pr is generated. Next, the new pump tilting command xL, which was increased in Step No. B1 to 3,
.

is substituted into the lever command value position. The procedure is again step Lim “2+
86+87+””9sS11+ 812-Is 5IJ
-2 is repeated, and the set pressure P is set at step fB12-2.
If it is determined that r has not been reached, the pump tilting command xL is further increased by 1 (512-3),
As mentioned above, via Stetsu 7″B12-4, Stetsu 7″S
5, the swash plate 1a is further driven in the (+) direction by a tilting angle corresponding to the value 1. This repetition is performed by the pressure detector 8a.
This process is continued until the pressure Pa detected at the point becomes equal to or higher than the set pressure Pr. When the pressure Pa exceeds the set pressure Pr,
The procedure moves to Stetsuno 5Xa-5, takes in the pump tilting amount Y detected by the displacement detector 4 at that time, and stores it in the RAM.
9 Store in a predetermined address of e. Then RAM
At the same time as the predetermined address of 9θ is increased by one, the number of the Sunnor counters is also increased by one."12-6
), set the tilt direction flag to (-). Note that the address does not necessarily have to be incremented by one, that is, it is not necessary to use an adjacent address, but this makes it easier to calculate the average value of the detected values. Increasing the number of this sample counter by one means that one piece of data has been stored, and contributes to the judgment in step 7'all. Furthermore, setting the tilting direction flag to (-) means preparing to tilt the swash plate 1a in the (-) direction in the next step.

When the step 7°5x2-y procedure is completed, Stella 7's
5 and return to Stella 7'S1. In the next repetition, since the tilting direction flag is (-), the process moves from Stella 7'812-1 to step 5xa-s.

In step S: L2-8, the pressure signal PI) from the pressure detector 8b is taken out and compared with the set pressure Pr. In this case, since the swash plate 1a is tilted in the (+) direction, the pressure signal PI) is less than the set pressure Pr. Therefore, in the next step 8xz-o, the pump tilting amount command x
Perform processing to decrease TJ by the value 1, and Stella 7'1
312 (at 0, this decreased pump tilting amount command XII is substituted for the lever command value X. Therefore, step 7''S5
, the swash plate 1a is driven in the (-) direction by a tilt angle corresponding to the value 1. As in the case of the (+) direction, this operation is repeated until the pressure signal PI) becomes equal to or higher than the set pressure pr. When the pressure signal Pb becomes equal to or higher than the set pressure Pr on step day 12-8, the procedure is Stella 7' Blz-
1x, and the signal Y1 of the displacement detector 4 at that time, that is, the pump tilting amount Y, is stored in the address next to the predetermined address of the RAM 9e. Then, set the address to the next address, and set the number of sample counters to 1.
(S: 12-12). Next, since the swash plate 1a is to be tilted in the (+) direction, the tilting direction flag is set to (+) (812-13).

As described above, the swash plate 1a is tilted by a predetermined amount in the (+) direction and the (-) direction, and the swash pump tilt amount Y at which the set pressure Pr is generated is memorized, and this is set in advance. Data collection is performed by repeating a number of times.

Once the data collection is completed, at Stetsuzo S Engineering,
Since it is determined that the number of sandals counter is the set value, the procedure moves to step s13.

Step 8.3 is an average value calculation routine that calculates the average value of the data collected by the steps up to that point, the details of which are shown in FIG. In the average value calculation routine s13, first, all the collected data are stored in the RAM.
'9e from each address and add them, and divide the added value by the number of data collection times (Sansol counter value) (B15-1).The obtained Xm is the pump's (
The average value obtained by adding the values of the signal Y when the same pressure is generated in the +) direction and the (-) direction and dividing the sum by the number of added values, in other words, the same pressure is generated ( +
This is the value of the signal Y at a position exactly halfway between the swash plate tilt position in the ) direction and the swash plate tilt position in the (-) direction. Therefore, this value Xm is the value of the signal Y when the actual pump tilt is in the neutral position. Note that in order to obtain such an average value, it is clear that the number of data collections must be the same in the (+) direction and the (-) direction, and the value of the Sansol counter (setting in Stetsuno S11) value) is an even number. Furthermore, by increasing this set value, a more accurate value Xm can be obtained. Next, this pump tilting neutral value Xm
Calculate the 0 correction amount Yo based on . The O correction amount Yo is the difference between the value of the signal Y when the pump tilt is actually at the neutral position and the value of the signal Y when the pump tilt is said to be at the neutral position (neutral value). This is the deviation value. Therefore, in order to compensate for the zero correction amount yo, the pump tilting neutral value Xm
An operation is performed to subtract the neutral value from (S1s-2
).

Note that when this neutral value is 0, the 0 correction amount y.

becomes the value Xm itself. When this calculation is completed, the procedure moves to step S5. 0 correction amount Y obtained in step 813-2. is stored at a predetermined address in the RAM 9θ, and will be taken out and used during processing in the step 7'S3 in subsequent control. When the start switch 10 is opened, the procedure from step S2 to step S6 is interrupted, the automatic neutral point detection operation is completed, and the normal control procedure is repeated.

In this way, in this embodiment, the swash plate is moved in the (+) direction and (-) direction.
The device is tilted alternately in multiple directions, and when a pressure higher than the set pressure is generated, a means is provided to receive the signal from the displacement detector and store the value, and a means to calculate the average value of these values. , the actual neutral point of the hydraulic pump can be automatically detected without manual intervention, and the hydraulic pump can be accurately controlled.

FIG. 11 is a system diagram of a part of the hydraulic circuit and electric circuit of an automatic neutral point detection device according to another embodiment of the present invention.

This embodiment differs from the embodiment shown in FIG. 5 only in that other detectors are used in place of the pressure detectors 8a+8b that continuously detect pressure, and the other configurations are as follows.
Since this embodiment is the same as the embodiment shown in the figures, explanation and illustration of the same parts will be omitted. Reference numeral 11 denotes a cylinder, which has ports &11 + bll communicating with ports (a and port) of the hydraulic pump 1 at both ends. 12 is cylinder 1
The pistons 13a and 13b moving left and right inside the piston 120 are connected to the piston 12 and the cylinder 1 at both ends of the piston 120.
It is a spring mounted between 10. Spring 13a.

13t) have the same spring force. 14a.

141) is a proximity switch that is actuated by movement of the piston 12. When the swash plate 1a is driven, pressure is applied to the port a11 or port a1)11', and the piston 12 is moved against the spring force of the Y4 spring 13a or spring 13b. A defined amount of movement of the piston 12 closes the proximity switch 14a or the proximity switch 141). The spring force of the springs 13a and 13b is adjusted, and when the aforementioned set pressure Pr is applied to the port a11 or port) bll, the proximity switch 14 & or the proximity switch 141
) is closed, automatic neutral point detection can be performed as in the previous embodiment. That is, the proximity switch 14a.

141) on/off state from the controller 90 input device 9
If input is made to ``g'', in step 810-4 of the initial setting routine and step 512-2 * 512-e of the data collection routine in the operation of the controller 9, it is necessary to determine whether the proximity switch 14a114b is on or off. This is a good thing, and the other steps do not need to be changed.

Note that the cylinder 11, piston 12, and spring 13a.

13b1 In place of the proximity switches 14a, 141), pressure switches are installed on the port a side and the port 1) side of the hydraulic cylinder f1, and the operating pressure is set as the set pressure, and the on/off state of the pressure switch is controlled by the controller. It may also be input to an input device.

It is clear that this embodiment also has the same effects as the rabbit embodiment.

In the description of the above embodiments, the start switch that instructs the start of automatic neutral point detection may of course be operated manually, but it is not operated manually and may be operated by some other operation, such as the prime mover that drives the pump. Closes in conjunction with the start operation of
The switch may be opened after a predetermined period of time, or the start of detection may be instructed when the switch is opened rather than when the switch is closed. Further, the reciprocating movement of the swash plate does not necessarily have to be performed multiple times, and detection may be performed by reciprocating once.

As is clear from the above, according to the present invention, the brake actuation device that instructs the operation of the brake device in response to the instruction from the start device, and the displacement variable mechanism of the hydraulic pump (+)
direction and (-) direction at least once each until the port pressure on the discharge side of the oil field pump detected by the pressure sensing device becomes at least approximately equal to the same predetermined set pressure, and the port pressure is A control device comprising: a data collection means for collecting the displacement value of the displacement variable mechanism at the time when the displacement becomes approximately equal to a set pressure; and an average value means for calculating the average value of the values collected by the data collection means. Since the neutral point of the pump is provided, the neutral point of the pump can be automatically detected without manual intervention, and the hydraulic pump can be controlled accurately.

[Brief explanation of the drawing]

Fig. 1 is a system diagram of an oil field circuit and an electric circuit of a conventional hydraulic pump control device equipped with a D-point correction circuit, and Fig. 2 is a block diagram showing the basic configuration of an automatic neutral point detection device for a hydraulic pump according to the present invention. 6 is a block diagram showing one embodiment of the data collection means in the control device shown in FIG. 2, FIG. 4 is a block diagram showing one embodiment of the initial setting means in the control device shown in FIG. 2, FIG. 5 is a block diagram showing an automatic neutral point detection device for an oil field pump according to an embodiment of the present invention;
FIG. 6 is a flowchart explaining the operation procedure stored in the ROM performed by the control device shown in FIG. 5, and FIGS. 7, 8, 9, and 10 are shown in FIG. 6, respectively. A flowchart showing details of the operating procedures of a bonder tilting servo routine, an initial setting routine, a data collection routine, and an average value calculation routine, No. 11 is one of the hydraulic bonder automatic neutral point detection apparatus according to another embodiment of the present invention. FIG. DESCRIPTION OF SYMBOLS 1... Hydraulic bonder, 1a... Swash plate, 2... Regulator, 3... Switching valve, 4... Displacement detector, 8a,
13b...Pressure detector, 9...Controller, 90
...Brake actuation means, 91...Data collection means,
92... Average value means, 93... Pump neutral means, 9
4... Initial setting means, 910... Port pressure determination means, 911... Bonder unit amount displacement means, 912...
Displacement reading means, 913... Reversing means, 940... Port pressure determining means, 941... Displacement direction determining means, 9
a...Multiplexer, 96 ・A/D converter,
9c...OPU, gam ROM. 9θ...RAM, 9f...Output device, 9g...Input device, 10...Switch, 11...Cylinder, 12.
... Gistone, 13a #131) - ... Spring, 14a1
141)...Proximity switch, 15...Brake device, 15a...Brake shoe, 15'b...Cylinder chamber, 15c...Spring, 16...Hydraulic pressure source, 17...
·tank. Agent Akira Asamura

Claims (8)

[Claims] (1) Automatic neutral point of an oil field pump that is equipped with a variable displacement mechanism that can be displaced in the (+) direction and (-) direction, is connected to at least one hydraulic actuator to form a hydraulic circuit, and drives the hydraulic actuator. The detection device includes: (a) a pressure detection device that detects port pressure of the hydraulic pump; (1)) a displacement detection device that detects displacement of the variable displacement mechanism; and (Q) a non-operating state of the hydraulic actuator. (d) a start device that instructs to start detecting the neutral point of the hydraulic pump; (e) a control device that detects the neutral point of the hydraulic pump; (f) The control device includes (I) a brake actuation means for instructing operation of the brake device in response to an instruction from the start device; and (I+) a variable displacement displacement device based on information from the pressure detection device and the displacement detection device. Mechanism (+
) direction and (-) direction at least once each, until the port pressure on the discharge side of the oil FE, - detected by the pressure sensing device becomes at least approximately equal to the same predetermined set pressure. data collecting means for collecting a displacement value of the variable displacement mechanism at the time when the port pressure becomes approximately equal to the set pressure;
01D An automatic neutral point detection device for a hydraulic pump, comprising: average value means for calculating an average value of the values collected by the data collection means. (2) The data collection means includes a port pressure determination means for determining whether or not the port pressure on the discharge side of the oil field pump is higher than the set pressure, and a port pressure determining means for determining whether the port pressure on the discharge side of the oil field pump is higher than the set pressure. It has a pump unit amount displacement means for displacing the variable displacement displacement mechanism by a predetermined unit amount, and a displacement reading means for reading the displacement of the variable displacement displacement mechanism when the poE force becomes approximately equal to the set pressure. An apparatus according to claim 1. (3) The control device is configured to (iV) respond to an instruction from the start device and displace the displacement volume variable mechanism to a neutral position at that time, prior to the operation of the data collection means and the average value means. 2. The device of claim 1 further comprising means. (4) (V) Based on the information from the pressure detection device, the control device determines the initial displacement direction of the displacement volume variable mechanism in the data collection device, prior to the operation of the data collection device and the average value device. 2. The apparatus of claim 1, further comprising initialization means for determining. (5) The initial setting means includes a port pressure determination means for determining whether or not one port pressure of the hydraulic ponder is greater than the set pressure when the displacement variable variable mechanism is in the neutral position; is not greater than the set pressure, the first displacement direction is made to match the direction in which the port pressure increases, and when the port pressure is greater than the set pressure, the first displacement direction is made to match the direction in which the port pressure decreases. 5. The device according to claim 4, further comprising displacement direction determining means for determining the displacement direction. (6) The data collecting means includes reversing means for reversing the displacement direction after collecting data by displacing the displacement variable mechanism in the initial displacement direction determined by the initial setting means. The device according to scope item 4. (7) Claim 1, wherein the pressure detection device is a pair of pressure detectors each connected to a pair of main pipes of the oil EE circuit and continuously measuring port pressure of the hydraulic pump. The device described. (8) The pressure detection device includes a cylinder connected between a pair of main pipes of the hydraulic circuit, a piston disposed within the cylinder and reciprocating therein, and a piston disposed in the cylinder and configured to move the piston. and a pair of proximity switches actuated by the apparatus of claim 1.