JPH0418165B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Application Field] The present invention provides a method for stopping a rotating body that automatically stops the rotating body at a predetermined position when a rotating body having a large inertia force is driven by a hydraulic motor. Regarding a control device.

[Conventional technology]

In a rotating body with a large inertial force, such as a hydraulic excavator, the upper rotating body, which is rotatably mounted on the traveling body, can rotate 360° with respect to the traveling body. Objects (e.g. earth and sand) can be transferred to other locations simply by pivoting the superstructure. Such a revolving body will be explained with reference to the drawings.

FIG. 3 is a top view of the upper revolving body of the hydraulic excavator. Reference numeral 1 indicates an upper revolving structure that is rotatably installed on a running body (not shown) of a hydraulic excavator;
is a front unit swingably attached to the upper revolving body 1. The front 2 is composed of a boom 3, an arm 4, and a bucket 5 that are swingably attached to each other. Reference numeral 6 denotes a hydraulic motor that drives the upper rotating body 1 to rotate relative to the traveling body. When the hydraulic motor 6 is driven in a certain direction, the revolving superstructure 1 rotates together with the front 2 on the traveling structure, for example, in the direction of arrow R, and when the hydraulic motor 6 stops, the revolving superstructure 1 also stops. Therefore,
Objects loaded on the bucket cart 5 can be transferred to a predetermined position, for example, the position indicated by the two-dot chain line in the figure.

FIG. 4 is a drive circuit diagram of the hydraulic motor. In the figure, 6 is the hydraulic motor shown in FIG. 3, 7 is a hydraulic pump that supplies pressure oil to the hydraulic motor 6, and 8 is the hydraulic motor 6 interposed between the hydraulic motor 6 and the hydraulic pump 7.
This is a directional control valve that controls the supply of pressure oil to.
A and B indicate the main circuit of the hydraulic motor 6. 9a, 9
b are relief valves connected between main circuits A and B, respectively.

Now, when the directional control valve 8 is switched to the left position in the figure, pressure oil from the hydraulic pump 7 is supplied to the hydraulic motor 6 via the main circuit A. This drives the hydraulic motor 6, and the oil from the hydraulic motor 6 is returned to the tank via the main circuit B. By driving this hydraulic motor 6, the upper revolving body 1 turns, for example, in the direction of arrow R in FIG. In this state, when the directional control valve 8 is returned to the neutral position as shown in the figure to stop the upper revolving structure 1, the pressure oil supply circuit from the hydraulic pump 7 and the return oil circuit from the hydraulic motor 6 to the tank are cut off. Then, the hydraulic motor 6 performs a pumping action due to the inertial force of the upper revolving structure 1, and the main circuit B becomes high pressure, and a braking force (stopping torque) corresponding to the pressure difference between the two main circuits A and B is generated. The revolving body 1 stops.

Incidentally, since the moment of inertia of the upper revolving structure 1 is extremely large, if the directional control valve 8 is set to the neutral position while the hydraulic motor 6 is being driven as described above, an abnormally high pressure will be generated in the main circuit B (the main circuit on the rotation direction side). occurs. For this reason, relief valves 9a and 9b are provided, and when the high pressure generated in the main circuit B exceeds the set pressure of the relief valve 9b, the pressure oil in the main circuit B is released to the main circuit A side.

In such a hydraulic circuit, the upper revolving body 1
Even if the directional control valve 8 is switched to the neutral position in an attempt to stop the hydraulic motor 6, the hydraulic motor 6 rotates while the pressure oil is relieved from the relief valve 9a or the relief valve 9b, and the upper rotating body 1 is rotated by the amount of pressure oil relieved. flows and stops. The amount of this flow (flow angle) is
As will be described later, the moment of inertia, the stopping torque, and the upper rotating structure 1 when the directional control valve 8 is changed.
Determined by the speed of

[Problem to be solved by the invention]

Conventionally, when an operator rotates the revolving upper structure 1, the operator stops the revolving upper structure 1 at a predetermined position while controlling the flow rate using the directional control valve 8 in consideration of the above flow rate. By the way, when the object (for example, earth and sand) loaded on the bucket cart 5 is transferred to a fixed fixed position and such transfer is performed repeatedly, there is a desire to automate the operation of the revolving upper structure 1. However, as mentioned above, when the revolving upper structure 1 is stopped, a flow rate determined by the moment of inertia, stopping torque, and speed occurs, and since these values are constantly changing, the flow rate is not constant. In automatic operation, there was a problem in that it was extremely difficult to stop the revolving superstructure 1 at a predetermined position. In this way, in order to implement automatic operation of the revolving superstructure 1, it is necessary to either ignore the extremely poor accuracy of its stopping position, or to
Alternatively, the only way to compensate for the deterioration in the accuracy of the stopping position was to extremely reduce the turning speed.

However, such transfer often requires precision in the stopping position, and a reduction in the rotation speed has the problem of significantly deteriorating work efficiency.

The present invention has been made in view of the above circumstances, and its purpose is to provide a stop control device for a rotating body that can solve the above-mentioned conventional problems and automatically stop a rotating body accurately at a predetermined position. is to provide.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a rotating structure having a large inertial force, a hydraulic motor for driving the rotating structure, and a hydraulic pump for supplying pressure oil to the hydraulic motor. A variable relief valve installed at the entrance and exit of the hydraulic motor,
a position detecting means for detecting the position of the rotating body; a first calculation means for calculating the speed and acceleration of the rotating body based on the detected value of the position detecting means;
a pressure detection means for detecting the pressure of the hydraulic motor; a stop position setting means for setting a position at which the rotating body should be stopped; a second calculating means for calculating a stopping torque and a moment of inertia of the rotating body; a third calculation for calculating the flow rate of the rotating body based on the detected value of the position detection means, the set value set by the stop position setting means, and the calculated values of the first calculation means and the second calculation means; means, and a stopping means for stopping the supply of pressure oil from the hydraulic pump to the hydraulic motor when the calculated value of the third calculating means becomes less than or equal to the distance from the current position of the rotating body to the set value. and relief pressure control means for controlling the set pressure of the variable relief valve so that the ratio of the stopping torque and the moment of inertia calculated by the second calculation means is constant.

[Effect]

When performing work using a revolving structure,
When the stopping torque and moment of inertia are calculated by the calculation means, based on these calculated values,
The flow rate of the rotating body when the rotating body is to be stopped is calculated by the third calculating means. and,
The flow rate is compared with the interval from the current position of the revolving body to the set position, and when the flow rate becomes equal to or less than the interval, a rotation stop operation of the revolving body is performed. Thereafter, the set pressure of the variable relief valve is controlled so that the ratio of the stopping torque to the moment of inertia at that point is constant.

〔Example〕

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

FIG. 1 is a system diagram of a stop control device according to an embodiment of the present invention. In the figure, parts that are the same as those shown in FIG. 4 are given the same reference numerals, and description thereof will be omitted. 8' is a directional control valve. While the directional control valve 8 shown in FIG. 4 may be either a manual type or an electromagnetic type,
The directional control valve 8' of this embodiment is of an electromagnetic type. Variable relief valves 11a and 11b are provided between the main circuits A and B, and their relief pressures can be changed in accordance with electrical signals.
12a and 12b are pressure sensors that detect the pressures of the main circuits A and B of the hydraulic motor b, respectively, and output signals corresponding to the pressures; 13 detects the rotation angle of the upper revolving structure 1 and outputs signals corresponding to the pressures; It is an angle sensor that outputs. Reference numeral 14 denotes a stop position setting device, which outputs a signal corresponding to the position (angle) at which the upper revolving body 1 is desired to be stopped. 15 is an arithmetic processing unit composed of a microcomputer, and includes pressure sensors 12a, 12b and an angle sensor 13.
and a signal from the stop position setter 14,
Calculations and controls are performed based on these input signals, and required signals are output to the directional switching valve 8' and the variable relief valves 11a and 11b to control them.

Next, the operation of this embodiment will be explained with reference to the flowchart shown in FIG. 2 and the top view of the revolving upper structure shown in FIG. In FIG. 3, S indicates a reference line for angles, and all angles in this embodiment are expressed as angles from the reference line S. This reference line may be set anywhere, but for example, the angle sensor 1
It is convenient to use the reference position No. 3 (for example, the position of output 0) as the reference line. θ is the angle of the current position of the revolving upper structure 1, and θ ₀ is the angle of the position at which the revolving upper structure 1 is desired to be stopped. The angle θ is obtained from the angle sensor 13, and
The angle θ ₀ is output from the stop position setting device 14 .

When the upper revolving body 1 turns in the direction of the arrow R in FIG.
is input from the angle sensor 13, and the angle θ ₀ is input from the stop position setting device 14 (step S ₁ shown in FIG. 2).
Based on these values, calculate the angular velocity θ〓, the angular acceleration θ¨, and the remaining angle from the current position to the stop position (θ−
θ ₀ ) is calculated (step S ₂ ). The method of calculating the angular velocity θ〓 and the angular acceleration θ〓 is well known, so a description thereof will be omitted.
Next, the signal p _i of the pressure sensor 12a and the signal p ₀ of the pressure sensor 12b are input (step S ₃ ), and the stopping torque T and the moment of inertia I are calculated based on these signals and the angular acceleration θ¨ calculated earlier. (Step _S4 ).

Here, calculation of the stopping torque T and the moment of inertia I will be explained. Both pressure sensors 12a, 12
Let P be the pressure difference between b and Q be the capacity of the hydraulic motor 6, then the stopping torque T can be calculated using the following equation.

T=P・Q/2π...(1) Moreover, the moment of inertia I can be calculated by the following formula.

I=T/θ... (2) In reality, these values are determined by taking motor efficiency etc. into consideration, but the details will be omitted.

Next, calculate the flow rate θ ₂ at that time (procedure
_S5 ). The flow rate θ ₂ can be calculated by the following equation based on the angular velocity at that time obtained in step S ₂ and the moment of inertia I and stopping torque T at that time obtained in step S ₄ .

θ ₂ = 1/2・I/T・(θ〓) ² ...(3) In other words, if the directional control valve 8' is set to the neutral position at that point and an attempt is made to stop the upper rotating structure 1, the upper rotating structure The angle through which the body 1 moves until it stops is calculated.

The flow rate θ ₂ calculated in this way is the remaining angle (θ − θ ₀ ) to the stop position calculated in step S ₂ .
(Step S ₆ ), and if the angle (θ - θ ₀ ) is larger than the flow angle θ ₂ , the procedure determines whether the angular velocity at that time is 0 (whether the upper rotating body 1 is in a stopped state or not). After making the determination in _S7 , return to step _S1 again. In this way, steps S ₁ to S ₇ are repeated, and eventually,
The _remaining angle (θ−
When it is determined that the flow angle θ ₀ ) has become equal to or less than the flow angle θ ₂ , the arithmetic and control unit 15 outputs a stop signal to the directional control valve 8' to switch it to the neutral position (step S ₈ ). The position of the revolving superstructure 1 determined as described above is shown by line C in FIG.
That is, if the directional control valve 8' is set to the neutral position at the position shown by line C, and the ratio of the moment of inertia I to the stopping torque T is kept constant as shown in equation (3), the upper rotating structure 1 flows by a flow rate θ ₂ and stops at the set position (position at angle θ ₀ ).

As mentioned above, in order to accurately stop the upper rotating body 1 at the set position, the moment of inertia I
Since it is assumed that the ratio between T and the stopping torque T is constant, a process for storing this ratio and keeping it constant will be executed below.

First, the ratio I/T between the moment of inertia I and the stopping torque T is calculated (step S 9 ), and it is determined whether this calculation is the first time (step S ₁₀ ). If it is the first time, the value I/T is calculated (step S ₉ ). It is stored in the storage unit as T=W ₀ (step S ₁₁ ), and the process returns to step S ₁ via step S ₇ described above. The processes of steps S ₁ to S ₆ and S ₈ to _{S 10} are repeated again, and this time, since the I/T calculation in step S ₉ is not the first time, the process moves to step S ₁₂ . In step _S12 , the value I/T calculated at that time in step _S9 is compared with the stored value _W0 . In this case, if there is a change in the moment of inertia I, the newly calculated value I/T and the value
It is inconsistent with W ₀ . Therefore, when a discrepancy occurs, a signal corresponding to the discrepancy is output to the variable relief valve (step _S12 ) to change the set pressure in order to make the discrepancy coincide. By changing this set pressure, the value of the stopping torque T changes in accordance with the change in the moment of inertia I, and the value I/T is always maintained to match the value _W0 . Thus,
When the upper revolving body 1 stops at the set stop position (angle θ ₀ ), the stop is determined in step _S7 , and the process ends.

In this way, in this embodiment, the flow rate is calculated based on the moment of inertia, stopping torque, and speed of the upper rotating body, and when the distance to the set stop position becomes less than the flow rate, the directional control valve is set to neutral. Since the variable relief valve is controlled to keep the ratio of the moment of inertia and the stopping torque constant, the upper revolving structure can be accurately stopped at a predetermined position.

In addition, in the description of the above-mentioned embodiment, an example was explained in which the hydraulic motor is controlled by the directional switching valve, but a double tilting hydraulic pump may be used as the hydraulic pump without using the directional switching valve. In this case, the stop signal output in step _S8 in the above embodiment becomes a signal output that makes the tilting of the double tilting hydraulic pump neutral.
Also, assuming that the set pressure in the variable relief valve is constant (relief valves, variable relief valves, even if the pressure is set to a certain value, the actual relief pressure usually fluctuates to some extent, If this is ignored), the pressure sensor is not required.

Furthermore, the moment of inertia is not necessarily calculated by the calculation method using equation (2), but may be calculated by the method described below. That is, an angle meter is attached to each swinging part of the front, and the position of the center of gravity of each link is calculated. Also, the weight of the load inside the bucket is detected by the pressure difference in the boom cylinder, etc. In this way, when the gravity m _i of each unit and the distance l _i from the center of rotation to the center of gravity are obtained, the moment of inertia I can be obtained from the following equation.

I=Σm _i・l _i ² /g ...(4) However, in the above formula, g is the gravitational acceleration.

Furthermore, in the description of the above embodiments, the upper revolving structure of a hydraulic excavator was exemplified as the revolving structure, but the present invention is not limited to this, and it goes without saying that other revolving structures may be used.

〔Effect of the invention〕

As described above, in the present invention, the flow rate is determined based on the moment of inertia, stopping torque, and speed of the rotating body, and when the distance to the set stop position becomes less than the flow rate, the pressure oil is supplied to the hydraulic motor. Since the variable relief valve is controlled to keep the ratio of the moment of inertia and the stopping torque constant, the rotating body can be accurately and automatically stopped at a predetermined position.

[Brief explanation of drawings]

FIG. 1 is a system diagram of a stop control device for a rotating body according to an embodiment of the present invention, FIG. 2 is a flowchart explaining the operation of the device shown in FIG. 1, and FIG. The top view and FIG. 4 are drive circuit diagrams of the hydraulic motor that drives the upper revolving body of the hydraulic excavator. DESCRIPTION OF SYMBOLS 1...Upper rotating body, 2...Front, 6...Hydraulic motor, 7...Hydraulic pump, 8'...Direction switching valve, 11a, 11b...Variable relief valve, 12
a, 12b...Pressure sensor, 13...Angle sensor, 14...Stop position setting device, 15...Arithmetic processing device.

Claims (1)

[Claims] 1 In a system equipped with a rotating body having a large inertial force, a hydraulic motor that drives the rotating body, and a hydraulic pump that supplies pressure oil to the hydraulic motor,
a variable relief valve attached to the entrance/exit of the hydraulic motor; a position detecting means for detecting the position of the rotating body; and a first means for calculating the speed and acceleration of the rotating body based on the detected values of the position detecting means. a calculation means, a pressure detection means for detecting the pressure of the hydraulic motor, a stop position setting means for setting a position at which the rotating body should be stopped, and a second calculation for calculating a stopping torque and a moment of inertia of the rotating body. a detection value of the position detection means, a set value set by the stop position setting means, and the first
and a third calculating means for calculating the flow rate of the rotating body based on the calculated value of the second calculating means, and the calculated value of the third calculating means is calculated from the current position of the rotating body to the setting. a stopping means for stopping the supply of pressure oil from the hydraulic pump to the hydraulic motor when the interval becomes less than or equal to the interval, and the ratio of the stopping torque to the moment of inertia calculated by the second calculating means is constant. A stop control device for a rotating body, characterized in that it is provided with relief pressure control means for controlling the set pressure of the variable relief valve.