JP6774502B2 - Stroke position reset processing method - Google Patents

Description

The present invention relates to a stroke position reset processing method capable of accurately obtaining a reset position by a reset position detection sensor even if there is a change in the distance between the sensor and the rod due to vibration or the like or a disturbance such as electromagnetic noise. This stroke position reset processing method is used, for example, to accurately detect the stroke of a working machine arm cylinder or boom cylinder of a hydraulic excavator which is an information technology construction machine (ICT construction machine).

A permanent magnet is provided on the piston that moves directly inside the cylinder tube such as a hydraulic cylinder together with the rod, and a magnetic force sensor is provided on the outside of the cylinder tube to detect the magnetic force passing through the magnetic force sensor to determine the position of the cylinder piston. There is something to measure.

For example, the cylinder head is provided with a rotary encoder that detects the amount of linear motion of the rod as the amount of rotation, and a magnetic force sensor for resetting is provided on the outer peripheral surface of the tube in the middle of the cylinder tube. Some magnets detect the magnetic force generated by a magnet fixed to a linearly moving piston, and when the magnetic force reaches the peak value, the measurement position obtained from the detected value of the rotary encoder is reset to the origin position.

Here, since the tube of the hydraulic cylinder is made of a magnetic material, there is a certain time delay (transmission delay) before the magnetism generated inside the tube reaches the magnetic force sensor outside the tube via the tube. On the other hand, the speed at which the piston inside the cylinder tube moves is not constant, so the stroke position obtained by arithmetic processing when the magnetic force detected by the magnetic force sensor (reset sensor) reaches its peak is true depending on the piston movement speed. It is deviated from the stroke position (origin position) of.

Therefore, in Patent Document 1, the correspondence between the passing speed directly under the reset sensor of the piston and the amount of displacement from the origin position (peak position correction amount) is acquired in advance and stored in a table format, and each stroke is stored. At times, the passing speed directly under the reset sensor is detected and the origin position is corrected.

In Patent Document 2, a plurality of detected recesses are provided on the outer peripheral surface of the cylinder block at intervals in the circumferential direction, and an electromagnetic pickup type rotation sensor detects the detected recesses when the cylinder block rotates. The one that measures the rotation speed of the cylinder block is described.

Japanese Unexamined Patent Publication No. 2006-226909 JP-A-2002-310062

By the way, the stroke position detection sensor provided in the cylinder tube measures the stroke position of the piston rod by converting the rotation amount of the rotating roller that is pressed by the piston rod and rotates into the stroke amount. It is inevitable that slippage will occur between the rotating roller and the piston rod, and this slippage will occur between the stroke position of the piston rod obtained from the detection result of the stroke position detection sensor and the actual stroke position of the piston rod. Causes a cumulative error due to slippage. Therefore, in order to reset the stroke position obtained from the detection result of the stroke position detection sensor to the origin position (reference position), a reset that separately detects the detected portion provided on the piston rod and resets the stroke position. A position detection sensor is provided.

Since it is necessary for the reset position detection sensor to accurately determine the reset position of the detected portion, two position detection sensors are arranged with respect to the sliding direction of the cylinder rod, and the detection results of each position detection sensor are used. I'm looking for a reset position.

However, if the detected portion provided on the piston rod is increased, the cost increases and the rod strength decreases, so it is necessary to make the detected portion as small as possible. Therefore, the detectable signal has to be small. As a result, there is a possibility that a change in the distance between the sensor and the rod due to vibration or the like or an erroneous detection due to disturbance such as electromagnetic noise may occur.

The present invention has been made in view of the above, and even if there is a change in the distance between the sensor and the rod due to vibration or the like or a disturbance such as electromagnetic noise, the reset position by the reset position detection sensor is obtained with high accuracy. It is an object of the present invention to provide a method of resetting a stroke position that can be performed.

In order to solve the above-mentioned problems and achieve the object, the stroke position reset processing method according to the present invention is provided on the stroke position detection sensor for detecting the stroke position of the linear motion member and on the linear motion member. This is a stroke position reset processing method for resetting the stroke position by using two reset position detection sensors that detect a detected portion having a width of a predetermined distance in the linear motion direction, and each reset position detection sensor. A detection step for detecting the output waveform of the above, a difference calculation step for calculating the difference waveform of the two detected output waveforms, and a stroke position at one end of the detected portion based on the difference waveform and the stroke position. It is characterized by including a reset position calculation step for calculating a reset position and a reset step for resetting the stroke position using the value of the reset position.

Further, in the stroke position reset processing method according to the present invention, in the above invention, the stroke position detection sensor and each reset position detection sensor perform position detection at predetermined sampling intervals, and the reset position calculation step is described. The value obtained by subtracting the second measurement value of the difference waveform behind by the predetermined distance from the first measurement value of the difference waveform calculated in the difference calculation step is obtained as the evaluation value of the first measurement value, and each stroke position is obtained. It is characterized in that the value obtained by weighted averaging with the evaluation value is calculated as the reset position.

Further, the stroke position reset processing method according to the present invention is characterized in that, in the above invention, the weighting averaging processing is performed when the evaluation value is equal to or more than a predetermined value.

Further, in the stroke position reset processing method according to the present invention, in the above invention, the two reset position detection sensors are magnetic sensors, and the detected portion is a groove provided on the background of the linear motion member. It is characterized in that it is a part that has been surface-treated with a non-magnetic material inside.

Further, in the stroke position reset processing method according to the present invention, in the above invention, the two reset position detection sensors are eddy current sensors, and the detected portion is provided on the sliding surface of the linear motion member. It is a metal in the groove, and is characterized in that the resistance value is lower than that of the material of the linear motion member.

Further, in the stroke position reset processing method according to the present invention, in the above invention, the two reset position detection sensors are optical sensors, and the detected portion is provided on the sliding surface of the linear motion member. It is a colored portion, and the color of the colored portion is different from the color of the sliding surface of the linear motion member.

Further, in the stroke position reset processing method according to the present invention, in the above invention, the two reset position detection sensors are optical sensors, and the detected portion is provided on the sliding surface of the linear motion member. It is characterized by being a light reflecting member or a light absorbing member.

According to the present invention, even if there is a change in the distance between the sensor and the rod due to vibration or the like or a disturbance such as electromagnetic noise, the reset position by the reset position detection sensor can be obtained with high accuracy.

FIG. 1 is a diagram showing an external configuration of a hydraulic cylinder with a stroke position detection function according to the first embodiment of the present invention. FIG. 2 is a cross-sectional view showing a detailed configuration of the hydraulic cylinder shown in FIG. FIG. 3 is an enlarged view showing a detailed configuration of the stroke position detection sensor shown in FIG. FIG. 4 is a diagram showing the configuration of the reset position detection sensor shown in FIG. 3 and the reset position detection process. FIG. 5 is an explanatory diagram illustrating the weighted averaging process. FIG. 6 is a flowchart showing a reset processing procedure by the arithmetic processing unit. FIG. 7 is a diagram showing the relationship between the measured stroke of the stroke position detection sensor and the actual stroke when the reset position detection sensor is arranged on the roller support portion of the stroke position detection sensor. FIG. 8 is a diagram showing the relationship between the measured stroke of the stroke position detection sensor and the actual stroke in the case of the conventional configuration in which the reset position detection sensor is not arranged on the roller support portion. FIG. 9 is a diagram showing a configuration and an output waveform of the reset position detection sensor used in the second embodiment of the present invention. FIG. 10 is a diagram showing a configuration of a reset position detection sensor according to a third embodiment of the present invention. FIG. 11 is a diagram showing an output waveform of the reset position detection sensor shown in FIG. FIG. 12 is a diagram showing a configuration of a reset position detection sensor according to a fourth embodiment of the present invention. FIG. 13 is a diagram showing an output waveform of the reset position detection sensor shown in FIG. FIG. 14 is a diagram showing a configuration of a reset position detection sensor according to a fifth embodiment of the present invention. FIG. 15 is a diagram showing an output waveform of the reset position detection sensor shown in FIG. FIG. 16 is a diagram showing a configuration of a reset position detection sensor according to a sixth embodiment of the present invention. FIG. 17 is a diagram showing an output waveform of the reset position detection sensor shown in FIG.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the accompanying drawings.

[Embodiment 1]
(Cylinder structure)
FIG. 1 is a diagram showing an external configuration of a hydraulic cylinder with a stroke position detection function (hereinafter, referred to as a hydraulic cylinder) 1 according to the first embodiment of the present invention. Further, FIG. 2 is a cross-sectional view showing a detailed configuration of the hydraulic cylinder 1 shown in FIG. Further, FIG. 3 is an enlarged view showing a detailed configuration of the stroke position detection sensor 10 shown in FIG.

As shown in FIGS. 1 and 2, the piston rod 3 which is a linear motion member is slidably provided on the cylinder tube 2 which is the wall of the hydraulic cylinder 1 via the piston 20. The piston 20 is attached near the cylinder bottom 9 side of the piston rod 3. Further, the piston rod 3 is slidably provided on the cylinder head 8. The chamber defined by the cylinder head 8, the piston 20, the inner wall of the cylinder tube 2, and the piston rod 3 constitutes the cylinder head side oil chamber 13H. Further, the chamber defined by the cylinder bottom 9, the piston 20, the inner wall of the cylinder tube 2, and the piston rod 3 constitutes the cylinder bottom side oil chamber 13B. The cylinder head side oil chamber 13H and the cylinder bottom side oil chamber 13B are positioned so as to face each other in the cylinder tube 2 via the piston 20. The hydraulic oil LH flows into and out of the cylinder head side oil chamber 13H via a hydraulic port 4 provided in the vicinity of the cylinder head 8. Further, the hydraulic oil LB flows into and out of the cylinder bottom side oil chamber 13B through the hydraulic port 5 provided in the vicinity of the cylinder bottom 9.

For the hydraulic oils LH and LB, the flow rate and direction of the hydraulic oil from the hydraulic pump (not shown) can be switched by adjusting the flow rate adjusting valve corresponding to the operation amount of the operating lever (not shown). When the hydraulic oil LH flows into the cylinder head side oil chamber 13H via the hydraulic port 4, the hydraulic oil LH pushes the piston 20 toward the cylinder bottom 9 side, so that the piston rod 3 moves to the cylinder bottom 9 side. Then, the hydraulic oil LB in the cylinder bottom side oil chamber 13B flows out to a hydraulic oil tank (not shown) through the hydraulic port 5. On the other hand, when the hydraulic oil LB flows into the cylinder bottom side oil chamber 13B via the hydraulic port 5, the hydraulic oil LB pushes the piston 20 toward the cylinder head 8 and the piston rod 3 moves toward the cylinder head 8. Then, the hydraulic oil LH in the cylinder head side oil chamber 13H flows out to a hydraulic oil tank (not shown) via the hydraulic port 4. As a result, the piston rod 3 reciprocates in the cylinder tube 2 in the linear motion direction AR due to the inflow of the hydraulic oils LH and LB.

The cylinder head 8 is provided with a rod seal 30 and a dust seal 32 that seal the gap with the piston rod 3 and prevent contamination such as dust from entering the cylinder head side oil chamber 13H.

(Stroke position detection mechanism)
A stroke position detection sensor 10 is provided outside the cylinder head 8. The stroke position detection sensor 10 is covered with a case 11. The case 11 is fastened to the cylinder head 8 with bolts or the like and fixed to the cylinder head 8. That is, the stroke position detection sensor 10 and the case 11 can be easily attached to and removed from the cylinder tube 2.

The surface of the rotating roller 12 constituting the stroke position detection sensor 10 comes into contact with the surface of the piston rod 3, is supported by the roller support portion 13, and is rotatably provided according to the reciprocating movement of the piston rod 3. That is, the linear movement amount of the piston rod 3 is converted into a rotation amount by the rotating roller 12.

The rotary roller 12 is arranged so that its rotation center axis 12C is orthogonal to the reciprocating direction of the piston rod 3. The case 11 is provided with a dust seal 31 that seals the gap between the piston rod 3 and prevents contamination such as dust from entering between the rotating roller 12 and the piston rod 3. As a result, it is possible to avoid a situation in which dust or the like enters between the rotary roller 12 and the piston rod 3 and the rotary roller 12 malfunctions. That is, the stroke position detection sensor 10 has a dustproof structure formed by a dust seal 31 provided on the case 11 and a dust seal 32 provided on the cylinder head 8.

A pressing spring 14 is arranged between the roller support portion 13 and the case 11. The pressing spring 14 presses the rotating roller 12 toward the piston rod 3 via the roller support portion 13 so that the rotating roller 12 does not slip with respect to the piston rod 3.

The stroke position detection sensor 10 has a rotation sensor unit (not shown) that detects the amount of rotation of the rotation roller 12. The signal indicating the amount of rotation of the rotating roller 12 detected by the rotation sensor unit is sent to the arithmetic processing unit 7 and converted into the stroke position of the piston rod 3. The arithmetic processing unit 7 outputs the calculated stroke position to a controller (not shown). The arithmetic processing unit 7 may be provided in the stroke position detection sensor 10.

It is inevitable that slip will occur between the rotating roller 12 of the stroke position detection sensor 10 and the piston rod 3, and the stroke of the piston rod 3 obtained from the detection result of the stroke position detection sensor 10 due to this slip. An error (cumulative error due to slippage) occurs between the position and the actual stroke position of the piston rod 3. Therefore, in order to reset the stroke position obtained from the detection result of the stroke position detection sensor 10 to the origin position (reference position), the roller support portion 13 is provided with the reset position detection sensor 15. The reset position detection sensor 15 is provided below the rotation center axis 12C of the rotation roller 12 (on the piston rod 3 side). This is because the lower part of the roller support portion 13 is closer to the piston rod 3 and the detected portion 40 can be detected more accurately. Further, the reset position detection sensor 15 is supported by the roller support portion 13 at the same fulcrum as the rotating roller 12. Further, the reset position detection sensor 15 and the rotary roller 12 are arranged on a straight line parallel to the linear motion direction AR of the piston rod 3.

The reset position detection sensor 15 detects the position of one end of the detected portion 40 provided at a predetermined surface position of the piston rod 3. As shown in FIG. 4A, the reset position detection sensor 15 of the first embodiment has magnetic sensors S1 and S2 such as Hall elements arranged in the linear motion direction AR. A magnet 41 is arranged above the reset position detection sensor 15. Further, the piston rod 3 is formed of a magnetic material, and a film of a non-magnetic material 43 is formed on the piston rod 3. Since the thickness of this film may be about 50 μm, for example, the thickness of the groove 42 having a depth of 50 μm is about 100 μm. The groove 42 is provided in a part of the ground surface (surface) of the piston rod 3. The non-magnetic material 43 is formed by a surface treatment (plating treatment) on the entire background including the groove 42.

(Reset process)
As shown in FIG. 4A, when the stroke direction is A1, the detected unit 40 is detected in the order of the magnetic sensors S1 and S2. When the magnetic sensors S1 and S2 approach the detected portion 40, the magnetic field is reduced due to the decrease in the magnetic material, and the Hall voltage of the Hall element is reduced. As a result, the magnetic sensors S1 and S2 output the output waveforms LS1 and LS2 shown in FIG. 4B, respectively. The output waveform LS1 is the detection result of the magnetic sensor S1, and the output waveform LS2 is the detection result of the magnetic sensor S2. As shown in FIG. 4C, the reset position detection sensor 15 outputs the difference waveform LΔV obtained by subtracting the output waveform LS2 from the output waveform LS1 to the arithmetic processing unit 7. The distance between the peaks of the difference waveform LΔV is characterized by being determined by the width W1 of the groove 42 of the detected portion 40.

Here, the arithmetic processing unit 7 can set the position where the difference waveform LΔV is maximum as the reset position d. In the first embodiment, the evaluation of the first measured value is obtained by subtracting the second measured value of the difference waveform behind the predetermined distance (width W1 of the detected unit 40) from the first measured value of the difference waveform. It is calculated as a value, and the value obtained by weighting and averaging each stroke position with each evaluation value is calculated as the reset position. FIG. 4D is a diagram showing changes in the evaluation value with respect to the stroke position. When the change in the evaluation value is weighted and averaged at the stroke position, the reset position d can be obtained. As described above, by utilizing the feature that the inter-peak distance of the difference waveform LΔV is the width W1 of the groove 42 of the detected portion 40, the reset position can be obtained without being affected by the disturbance.

FIG. 5 is an explanatory diagram illustrating the weighted averaging process. The difference waveform LΔV shown in FIGS. 5A to 5D corresponds to FIG. 4C and has sampling points SP1 to SP7. In FIG. 5A, the evaluation value “0” is obtained by subtracting the second measured value of the sampling point SP1 from the first measured value of the sampling point SP4. In FIG. 5B, the evaluation value “3” is obtained by subtracting the second measured value of the sampling point SP2 from the first measured value of the sampling point SP5. In FIG. 5C, the evaluation value “3” is obtained by subtracting the second measured value of the sampling point SP3 from the first measured value of the sampling point SP6. In FIG. 5D, the evaluation value “0” is obtained by subtracting the second measured value of the sampling point SP4 from the first measured value of the sampling point SP7. That is, the evaluation value shown in FIG. 5 (e) is obtained. In the subtraction process for obtaining the evaluation value, the distance between the sampling points is set to the width W1, but if there is no sampling point corresponding to the width W1, the sampling point closest to the width W1 is substituted.

Here, when the evaluation value exceeds a predetermined value, for example, "2", a weighted averaging process is performed to obtain the reset position d, which is the end position P1 on the cylinder bottom side of the detected unit 40. When the stroke positions of the sampling points SP4 to SP7 at each sampling point are "1 mm", "2 mm", "3 mm", and "4 mm", each stroke position is set to each evaluation value "0", "3", "3". , "0", the weighted averaging process is performed as in the following equation to obtain the reset position d by estimation.
d = (1 mm x 0 + 2 mm x 3 + 3 mm x 3 + 4 mm x 0) / (0 + 3 + 3 + 0) = 2.5 mm

Then, the arithmetic processing unit 7 resets the stroke position at the obtained reset position d. Specifically, when the reset position d is the origin (stroke position = 0 mm), the value obtained by subtracting the reset position d (= 2.5 mm) from the current stroke position is corrected as the true stroke position (origin).

Here, the reset processing procedure by the arithmetic processing unit 7 will be described with reference to the flowchart shown in FIG. This process is performed at each sampling interval. First, the arithmetic processing unit 7 holds the stroke position detected by the stroke position detection sensor 10 and each output waveform (each output) detected by the magnetic sensors S1 and S2, which are the two reset position detection sensors (step). S101). After that, the arithmetic processing unit 7 calculates a difference waveform obtained by taking the difference between the two output waveforms, and holds the difference waveform (step S102).

After that, as shown in FIGS. 5A to 5D described above, the evaluation value at the current sampling point is calculated (step S103). Further, it is determined whether or not the calculated evaluation value is equal to or greater than a predetermined value, for example, "2" or more (step S104).

When the evaluation value is equal to or greater than a predetermined value (step S104, Yes), the stroke positions of a predetermined number of sampling points before and after the current sampling point (predetermined distance before and after the current sampling point) are weighted with the evaluation value of each sampling point. The average value is calculated as the reset position d (step S105). After that, the stroke position is reset at the calculated reset position d (step S106), and the processing at the current sampling point is completed. On the other hand, if the evaluation value is not equal to or higher than the predetermined value (steps S104, No), the process at the current sampling point is terminated as it is. Then, the above-described processing is repeated at each sampling time point.

The evaluation value does not have to be calculated every time. For example, the calculation of the evaluation value may be started by triggering that one of the two output waveforms is lowered.

(Arrangement of reset position detection sensor)
In the first embodiment, as described above, the reset position detection sensor 15 is arranged on the roller support portion 13 of the stroke position detection sensor 10. As shown in the schematic view of the state 1 of FIG. 7, since the roller support portion 13 moves up and down, a gap ΔG is provided on the sliding surface between the roller support portion 13 and the case 11. As a result, when the piston rod 3 slides, the rotating roller 12 and the roller support portion 13 may tilt obliquely with respect to the linear motion direction of the piston rod 3. The inclination of the roller support portion 13 becomes a stroke error.

FIG. 7 is a diagram showing the relationship between the measured stroke of the stroke position detection sensor 10 and the actual stroke when the reset position detection sensor 15 is arranged on the roller support portion 13 of the stroke position detection sensor 10. In FIG. 7, the roller support portion 13 is in a neutral state (state 1) where there is no inclination, the roller support portion 13 is tilted in the positive direction (stroke direction with respect to the piston rod 3) from the state 1, and the reset position is in the state 2. Schematic diagram when the roller support portion 13 is tilted in the negative direction (opposite to the stroke direction with respect to the piston rod 3) from the state 3 where the detection sensor 15 has detected the reset position and the state 2 after the state 3. And the detection characteristics of the measured stroke and the actual stroke are shown. The straight line L1 shown in the detection characteristics shows the characteristics of the measured stroke and the actual stroke in the neutral state. The straight line L2 shows the characteristics of the measured stroke and the actual stroke when the inclination of the roller support portion 13 in the positive direction is maximum. The straight line L3 shows the characteristics of the measured stroke and the actual stroke when the inclination of the roller support portion 13 in the negative direction is maximum.

First, in the state 1, the piston rod 3 is at the reference position, that is, the detected portion 40 is at the position of the actual stroke 0, the roller support portion 13 is not tilted, and the measurement stroke and the actual stroke are “0”. At this time, the position detected by the reset position detection sensor 15 is at a distance "B" in the positive direction (stroke direction) with respect to the reference position. The stroke position detection sensor 10 detects the relative stroke as the measurement stroke with the position of the detected portion 40 as the reference position “0”.

After that, when the piston rod 3 extends in the positive direction, the measurement stroke and the actual stroke change along the straight line L1. Here, when the roller support portion 13 is in the state 2 tilted in the positive direction, the stroke position detection sensor 10 is rotated by the tilt, and the rotating roller 12 is excessively rotated clockwise in the drawing as shown by the arrow. Since the distance "A" is measured extra, the measurement stroke is increased by "+ A", and the measurement stroke and the actual stroke change along the straight line L2.

In the state 3 in which the reset position detection sensor 15 detects the detected portion 40 which is the reset position in this state 2, the actual stroke is "BA", but the measurement stroke is reset as "B". Therefore, the measurement stroke has an error of "+ A" with respect to the actual stroke.

Further, when the state 3 is changed to the state 4, the roller support portion 13 is tilted in the positive direction, the roller support portion 13 is tilted in the negative direction (counterclockwise stroke direction), and the rotating roller 12 is indicated by an arrow. In the figure, it rotates counterclockwise extra, and the distance "-2A" for this rotation is extra-measured. Therefore, the measurement stroke is measured less than the actual stroke by "-A". Therefore, the measurement stroke has an error of "-A" with respect to the actual stroke.

On the other hand, as shown in FIG. 8, when the reset position detection sensor 115 is not arranged on the roller support portion 113, the error ΔE of the measurement stroke is outside ± A with respect to the actual stroke, and the accuracy of the stroke measurement becomes low. ..

FIG. 8 is a diagram showing the relationship between the measured stroke of the stroke position detection sensor and the actual stroke in the case of the conventional configuration in which the reset position detection sensor 115 is not arranged on the roller support portion 113. States 1 to 4 in FIG. 8 are the same as states 1 to 4 in FIG. The rotary roller 112 and the roller support portion 113 correspond to the rotary roller 12 and the roller support portion 13, respectively. The reset position detection sensor 115 corresponds to the reset position detection sensor 15, and detects the detected portion 141, which is a magnet arranged on the cylinder tube and arranged on the piston 20.

First, in the state 1 of FIG. 8, the piston rod 3 is at the reference position, that is, the detected portion 141 is at the position of the actual stroke 0, the roller support portion 113 is not tilted, and the measurement stroke and the actual stroke are “0”. .. At this time, the position detected by the reset position detection sensor 115 is at a distance "B" in the positive direction (stroke direction) with respect to the reference position. The stroke position detection sensor detects the relative stroke as the measurement stroke with the position of the detected unit 141 as the reference position “0”.

After that, when the piston rod 3 extends in the positive direction, the measurement stroke and the actual stroke change along the straight line L1. Here, when the roller support portion 113 is tilted in the positive direction 2, the stroke position detection sensor rotates the rotating roller 112 extra clockwise as shown by the arrow due to the tilt, and the amount of this rotation is increased. Since the distance "A" is additionally measured, the measurement stroke is increased by "+ A", and the measurement stroke and the actual stroke change along the straight line L2.

In the state 3 where the reset position detection sensor 115 detects the detected portion 141 which is the reset position in this state 2, the stroke measured by the stroke position sensor is "B + A", but it is measured by resetting the reset position detection sensor 115. The stroke is reset as "B". Therefore, the measurement stroke is "B", which is the same as the actual stroke.

Further, when the state 3 is changed to the state 4, the roller support 113 is tilted in the positive direction, the roller support 113 is tilted in the negative direction (reverse stroke direction), and the rotating roller 112 is indicated by an arrow. In the figure, it rotates counterclockwise extra, and the distance "-2A" for this rotation is extra-measured. Therefore, the measurement stroke is measured less than the reset actual stroke by "-2A". Therefore, the measurement stroke has an error of "-2A" with respect to the actual stroke.

That is, as shown in the state 3 of FIG. 8, when the reset position detection sensor 115 detects the reset position while the roller support portion 113 is tilted in the positive direction, the measurement stroke “B” is reset to the actual stroke “B”. However, the reset is performed when the roller support portion 113 is tilted. Then, in the state 4, the inclination of the roller support portion 113 changes from the positive direction to the negative direction, so that the measurement stroke is reduced (“-2A”) by “2A” from the straight line L1 and is out of the range of the error ΔE. It sticks out.

In the first embodiment, even if the roller support portion 13 is tilted to the maximum in the positive direction or the negative direction, the reset position detection sensor 15 is arranged on the roller support portion 13, so that the measurement stroke is actual. The error ΔE is within ± A with respect to the stroke, and highly accurate stroke measurement becomes possible.

[Embodiment 2]
In the first embodiment described above, two magnetic sensors S1 and S2 are used, but in the second embodiment, the reset position d is detected by using one magnetic sensor S3.

FIG. 9 is a diagram showing a configuration and an output waveform of the reset position detection sensor 15 used in the second embodiment of the present invention. As shown in FIG. 9, the reset position detection sensor 15 detects the detected portion 40 with one magnetic sensor S3. The magnetic sensor S3 outputs the output waveform LS3 shown in FIG. 9B. The arithmetic processing unit 7 detects the rising position of the output waveform LS3 as the reset position d.

[Embodiment 3]
In the first embodiment described above, the magnetic sensors S1 and S2 are used as the reset position detection sensor 15, but in the third embodiment, the eddy current sensors S51 and S52 are used as the reset position detection sensor 15. ..

As shown in FIG. 10, the eddy current sensors S51 and S52 are coils, and the detected portion 40a of the piston rod 3 uses a metal having a resistance value lower than that of the material of the piston rod 3, for example, copper.

The arithmetic processing unit 57 corresponding to the arithmetic processing unit 7 corresponds to the eddy current sensors S51 and S52, and corresponds to the oscillation circuit 50, the resonance circuits 51a and 51b, the detection circuits 52a and 52b, the amplifier circuits 53a and 53b, and the differential amplifier circuit. Has 54. The resonance circuits 51a and 51b are connected to the eddy current sensors S51 and S52, respectively, generate a high-frequency resonance frequency corresponding to the oscillation frequency from the oscillation circuit 50, and generate a magnetic field of the resonance frequency from the eddy current sensors S51 and S52, respectively. ing. The detection circuits 52a and 52b detect the resonance waveforms of the resonance circuits 51a and 51b, respectively. The amplifier circuits 53a and 53b amplify the detection waveform, respectively. The differential amplifier circuit 54 outputs a difference waveform obtained by subtracting the amplification waveform output by the amplifier circuit 53b from the amplification waveform output by the amplifier circuit 53a. Then, the arithmetic processing unit 57 detects the reset position and resets the stroke position based on the difference waveform in the same manner as in the first embodiment.

When the eddy current sensors S51 and S52 approach each other, the detected unit 40a generates an eddy current in the detected unit 40a to increase the impedance. When the impedance of the detected unit 40a increases, the resonance frequencies of the resonance circuits 51a and 51b change, so that the amplitude of the detection waveform detected by the detection circuits 52a and 52b becomes small. Therefore, as shown in FIG. 11A, the voltage of the amplified waveforms L53a and L53b output by the amplifier circuits 53a and 53b decreases due to the proximity of the detected unit 40a.

The differential amplifier circuit 54 generates a differential waveform L53ΔV obtained by subtracting the amplification waveform L53b from the amplification waveform L53a as described above. The width W5 between the peak values of the difference waveform L53ΔV corresponds to the width W5 of the detected portion 40a. This difference waveform L53ΔV corresponds to the difference waveform LΔV shown in FIG. 4C.

[Embodiment 4]
In the third embodiment described above, two eddy current sensors S51 and S52 are used, but in the fourth embodiment, the reset position d is detected by using one eddy current sensor S52.

FIG. 12 is a diagram showing a configuration of a reset position detection sensor using the eddy current sensor S52 according to the fourth embodiment of the present invention. In the reset position detection sensor shown in FIG. 12, the eddy current sensor S51 shown in FIG. 10 is deleted, and the resonance circuit 51a, the detection circuit 52a, the amplifier circuit 53a, and the differential amplifier circuit 54 in the arithmetic processing unit 57 are deleted. It was done. Therefore, as shown in FIG. 13, the arithmetic processing unit 57'corresponding to the arithmetic processing unit 57 detects the rising position of the amplification waveform L53b output by the amplifier circuit 53b as the reset position and resets the stroke position.

[Embodiment 5]
In the first embodiment described above, the magnetic sensors S1 and S2 are used as the reset position detection sensor 15, but in the fifth embodiment, an optical sensor is used as the reset position detection sensor 15. As shown in FIG. 14, the optical sensor has a light emitting element S60 and two light receiving elements S61a and S61b. That is, the reset position detection sensor of the fifth embodiment has two optical sensors in which the light emitting element S60 and the light receiving element S61a are one optical sensor and the light emitting element S60 and the light receiving element S61b are one optical sensor.

The arithmetic processing unit 67 corresponding to the arithmetic processing unit 7 receives light from the output waveforms of the light emitting circuit 60 for emitting the light emitting element S60, the light receiving signals 61a and 61b for receiving the light receiving signals from the light receiving elements S61a and S61b, and the light receiving circuit 61a. It has a differential amplifier circuit 62 that outputs a difference waveform obtained by subtracting the output waveform of the circuit 61b. Based on this difference waveform, the arithmetic processing unit 67 detects the reset position and resets the stroke position in the same manner as in the first embodiment.

The detected portion 40b is a colored portion, and the color of the colored portion is different from the color of the sliding surface of the piston rod 3. Specifically, it is black and absorbs light. When the detected unit 40b approaches the light reflection position, the amount of reflection of the light receiving circuits 61a and 61b decreases, and as shown in FIG. 15A, the voltages of the output waveforms L61a and L61b decrease. As shown in FIG. 15B, the differential amplifier circuit 62 generates a differential waveform L62ΔV obtained by subtracting the output waveform L61b from the output waveform L61a. The width W6 between the peak values of the difference waveform L62ΔV corresponds to the width W6 of the detected unit 40b. This difference waveform L62ΔV corresponds to the difference waveform LΔV shown in FIG. 4C.

The detected portion 40b may be a reflective member that reflects light. Further, the member may be colored with a predetermined color. When colored with a predetermined color, it is preferable that the light receiving elements S61a and S61b can receive only the predetermined color.

[Embodiment 6]
In the above-described fifth embodiment, two optical sensors are used, but in the sixth embodiment, as shown in FIG. 16, one optical sensor including the light emitting element S60 and the light receiving element S61b is used to set the reset position. It is being detected.

FIG. 16 is a diagram showing a configuration of a reset position detection sensor using one optical sensor according to the sixth embodiment of the present invention. The reset position detection sensor shown in FIG. 16 is obtained by deleting the light receiving element S61a shown in FIG. 14 and deleting the light receiving circuit 61a and the differential amplifier circuit 62 in the arithmetic processing unit 67. Therefore, as shown in FIG. 17, the arithmetic processing unit 67'corresponding to the arithmetic processing unit 67 detects the rising position of the output waveform L61b output by the light receiving circuit 61b as a reset position and resets the stroke position.

The reset process of the first embodiment shown in FIG. 6 can be applied to the third and fifth embodiments using the two reset position detection sensors. Further, in the second to sixth embodiments, the reset position detection sensor is arranged on the roller support portion 13, so that the measurement stroke has an error ΔE within ± A with respect to the actual stroke as shown in the first embodiment. Therefore, highly accurate stroke measurement becomes possible. Needless to say, the present invention is applied not only to hydraulic excavators but also to construction machines and industrial vehicles having working machines such as bulldozers, loaders and graders.

1 Hydraulic cylinder, 2 Cylinder tube, 3 Piston rod, 4, 5 Hydraulic port, 7, 57, 57', 67, 67' Arithmetic processing unit, 8 Cylinder head, 9 Cylinder bottom, 10 Stroke position detection sensor, 11 case, 12,112 rotary roller, 12C rotary center shaft, 13H cylinder head side oil chamber, 13B cylinder bottom side oil chamber, 13 roller support, 14 pressing spring, 15,115 reset position detection sensor, 20 piston, 30 rod seal, 31, 32 Dust seal, 40, 40a, 40b Detected part, 41 magnet, 42 groove, 43 non-magnetic material, 50 oscillation circuit, 51a, 51b resonance circuit, 52a, 52b detection circuit, 53a, 53b amplifier circuit, 54, 62 Differential amplifier circuit, 60 floodlight circuit, 61a, 61b light receiving circuit, 141 detected part, AR linear motion direction, d reset position, L1 to L3 straight line, L53a, L53b amplification waveform, L53ΔV, L62ΔV, LΔV difference waveform, L61a , L61b, LS1, LS2, LS3 Output waveform, LH, LB hydraulic oil, P1 end position, S1, S2, S3 magnetic sensor, S51, S52 vortex current sensor, S60 light emitting element, S61a, S61b light receiving element, SP1 to SP7 Sampling point, W1, W5, W6 width, ΔE error, ΔG gap.

Claims (5)

A stroke position detection sensor that detects the stroke position of the linear motion member, and a groove provided on the linear motion member and provided on the surface of the linear motion member and having a width of a predetermined distance in the linear motion direction to be detected. It is a stroke position reset processing method for resetting the stroke position by using two reset position detection sensors for detecting a unit.
A detection step that detects the output waveform of each reset position detection sensor,
A difference calculation step for calculating the difference waveform of the two detected output waveforms, and
A reset position calculation step for calculating a reset position, which is a stroke position at one end of the detected portion, based on the difference waveform and the stroke position.
A reset step that resets the stroke position using the value of the reset position, and
Including
The stroke position detection sensor and each reset position detection sensor perform position detection at predetermined sampling intervals, and then perform position detection.
In the reset position calculation step, a value obtained by subtracting the second measurement value of the difference waveform located at the predetermined distance and behind from the first measurement value of the difference waveform calculated in the difference calculation step is used as the evaluation value of the first measurement value. A method for resetting a stroke position, which comprises calculating a value obtained by weighting and averaging each stroke position with each evaluation value when the evaluation value is equal to or more than a predetermined value as the reset position. The two reset position detection sensors are magnetic sensors.
The object detection unit, a reset processing method of the stroke position according to claim 1, characterized in that a portion subjected to surface treatment with a non-magnetic material in the groove provided in the background of the linear motion member. The two reset position detection sensors are eddy current sensors.
Wherein the detected portion, the linear motion member is a metal in the grooves provided on the sliding surface of stroke position according to claim 1, characterized in that a lower resistance value than the material of the linear motion member Reset processing method. The two reset position detection sensors are optical sensors.
The detected portion is a colored portion provided on the sliding surface of the linear motion member, and the color of the colored portion is different from the color of the sliding surface of the linear motion member according to claim 1 . The method of resetting the stroke position described. The two reset position detection sensors are optical sensors.
The stroke position reset processing method according to claim 1, wherein the detected portion is a light reflecting member or a light absorbing member provided on a sliding surface of the linear motion member.

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