JP2007333628A - Apparatus for measuring cylinder stroke position in working machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To readily adjust the resetting of a detent release position and in a short time, and allow fine adjustments over a wide range, as in the case of making fine adjustments on the mounting position of a proximity switch. <P>SOLUTION: A cylinder 200 is provided with a cylinder stroke sensor 300 for detecting a stroke position St of the cylinder 200 by using magnetism as a medium. An arithmetic processing section 400 compares the detection signal S of the cylinder stroke sensor 300 with a threshold T and the comparison result is output. The threshold T is, for example, set as a cylinder stroke position corresponding to a detent release position. In a threshold adjustment section 500 the magnitude of the threshold T is adjusted. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a cylinder stroke position measuring device in a work machine, and more particularly to a position measuring device that measures the position of a rod and a piston that move linearly inside a cylinder tube.

  As shown in FIG. 1A, in a construction machine such as a wheel loader 1, a boom cylinder (lift cylinder) 4 for operating a boom 3 at a front part of a vehicle body 2 and raising a boom in a boom lowering direction, a bucket A bucket cylinder (dump cylinder) 6 is provided to operate 5 in the tilt direction and the dump direction. As shown in FIG. 1B, when the operating lever 7 for the work implement provided in the driver's seat is operated from the neutral position, the boom operating valve 8 and the bucket operating valve 9 are opened according to the operation. The pressure oil is supplied to the boom cylinder 4 and the bucket cylinder 6, and the boom 3 and the bucket 5 are operated.

The work machine operation lever 7 has a detent function. The detent function is a function for holding the work machine operation lever 7 at a predetermined operation stroke position.

Whether the detent function is maintained or released is determined by a signal output from a proximity switch provided in the work machine.

That is, as shown in FIG. 1C, the proximity switch 12 is provided on the frame of the wheel loader 1. On the front surface of the detection surface of the proximity switch 12, a detection body 13 that operates together with the rotation operation of the boom 3 is disposed. When the height of the boom 3 is lower than the predetermined detent release position, the detection body 13 is present in front of the detection surface of the proximity switch 12, and therefore the current i1 for maintaining the detent function is output from the proximity switch 12. The Further, when the height of the boom 3 is equal to or higher than a predetermined detent release position, the detection body 13 is separated from the front surface of the detection surface of the proximity switch 12, and thus the current i1 output from the proximity switch 12 is turned off.

Therefore, as shown in FIG. 1B, when the operator operates the work implement operating lever 7 in the boom raising direction, as long as the boom 3 is below the detent release position, the proximity switch 12 i1 is added to the solenoid 14 of the boom detent portion of the work implement operating lever 7, and the solenoid 14 maintains the biased state, and the spool fixes the work implement operating lever 7 at a predetermined boom raising operation position. As a result, the boom 3 is raised while the work implement operating lever 7 is held at the predetermined boom raising position. When the height of the boom 3 reaches the detent release position, the current i1 output from the proximity switch 12 is turned off, the solenoid 14 is de-energized, the spool returns, and the work machine operation lever 7 is returned to the neutral position. The detent function is canceled. Such a function is called a boom kickout.

On the other hand, as shown in FIG. 1 (d), a proximity switch 15 is provided on the body of the bucket cylinder 6. On the front surface of the detection body of the proximity switch 15, a detection body 16 that operates together with the rotation of the bucket 5 is disposed. When the bucket 5 is closer to the dumping direction than the predetermined detent release position, the detector 16 is present in front of the detection surface of the proximity switch 15, and therefore the proximity switch 15 outputs a current i2 for maintaining the detent function. Is done. When the bucket 5 is on the tilt direction side with respect to the predetermined detent release position, the detection body 16 is separated from the front surface of the detection surface of the proximity switch 15, so that the current i2 output from the proximity switch 15 is turned off.

For this reason, as shown in FIG. 1B, when the operator operates the operating lever 7 for work implement in the tilt direction, the current i2 is supplied from the proximity switch 15 as long as the bucket 5 is on the dumping direction side of the detent release position. In addition to the solenoid 17 of the bucket detent portion of the work machine operation lever 7, the solenoid 17 maintains the biased state, and the spool fixes the work machine operation lever 7 at a predetermined tilt operation position. As a result, the bucket 5 tilts while the work implement operating lever 7 is held at the predetermined tilt position. When the bucket 5 reaches the detent release position, the current i2 output from the proximity switch 15 is turned off, the solenoid 17 is de-energized, the spool is returned, and the work machine operation lever 7 is returned to the neutral position. Is released. Such a function is called a bucket positioner.

The functions of the boom kickout and bucket positioner described above are to release the detent function when the boom or bucket reaches a predetermined position and posture, and are provided to improve operability during excavation and loading. Yes.

Patent Document 1 below discloses an invention in which a mechanism for winding a wire in response to movement of a rod of a boom cylinder is provided, and the cylinder stroke position is measured by detecting the winding amount of the wire with a potentiometer. Are listed.

In Patent Document 2 below, a magnet is provided on the rod of the lift cylinder, and a magnetic sensor is provided at each of two locations in the cylinder stroke direction outside the outer tube of the lift cylinder, and the detection outputs of the magnetic sensors are compared. An invention is described in which the cylinder stroke position is measured according to the magnitude of both detection outputs.
JP 2005-83106 A No. 4-40409

  The detent release position described above often needs to be changed according to the preference of the operator and the work content. For example, the detent release position may be changed depending on the height of the loading platform of the truck on which the load is loaded by the wheel loader, the size of the bucket attached to the wheel loader, or the like.

  However, in order to reset the detent release position, it is necessary to finely adjust the attachment positions of the proximity switches 12 and 15, and there is a problem that the adjustment is complicated and takes time.

  Patent Document 1 merely discloses a technique for measuring a potentiometer detection signal as a cylinder stroke position, and determines that a predetermined detent position has been reached from the potentiometer detection signal, or determines the detent release position. There is no particular description regarding the changes.

  Similarly, Patent Document 2 only discloses a technique for measuring the cylinder stroke position based on the magnitude of the detection output of each magnetic sensor, and has reached a predetermined detent position from the detection signal of the magnetic sensor. There is no particular description regarding the point of determining or changing the detent release position.

The present invention has been made in view of such circumstances, and when resetting the detent release position, the adjustment can be easily performed in a short time, and is similar to the case of finely adjusting the attachment position of the proximity switch. The problem to be solved is to enable fine adjustment over a wide range.

The first invention is
A cylinder stroke position measuring device in a work machine for measuring a stroke position of a cylinder (200) of the work machine (1),
A cylinder stroke sensor (300) attached to the cylinder (200) for detecting the stroke position of the cylinder using magnetism as a medium;
An arithmetic processing unit (400) that compares a detection signal of the cylinder stroke sensor (300) with a threshold value and outputs a comparison result;
And a threshold adjustment unit (500) for performing an input operation for adjusting the magnitude of the threshold.

The second invention is the first invention,
It is configured so that a detection signal having a characteristic of continuously outputting a convex peak upward and a convex peak downward can be obtained from the detection signal of the cylinder stroke sensor (300) as the cylinder stroke position changes. It is characterized by.

The third invention is the first invention,
At least two (301, 302) cylinder stroke sensors (300) are arranged in the direction in which the position of the cylinder stroke changes. By combining the detection signals of the cylinder stroke sensors (301, 302), the cylinder stroke sensor (300) protrudes upward. This is characterized in that a detection signal having a characteristic of continuously outputting a peak and a peak protruding downward is obtained.

The first invention will be described with reference to FIG. 2, FIG. 3, and FIG.

As shown in FIGS. 2 and 3, the cylinder 200 is provided with a cylinder stroke sensor 300 that detects the stroke position St of the cylinder 200 using magnetism as a medium. In the arithmetic processing unit 400, the detection signal S of the cylinder stroke sensor 300 and the threshold value T are compared and a comparison result is output. For example, the threshold value T is set as a cylinder stroke position corresponding to the detent release position. In the threshold adjustment unit 500, the magnitude of the threshold T is adjusted. As shown in FIG. 5 (c), in the cylinder stroke sensor 300 that detects the cylinder stroke position St using magnetism as a medium, the peak of the detection signal S is wide and the threshold value extends over a wide stroke range SA. The size of T can be changed. For this reason, the adjustment range of the detent release position can be widened. In other words, the adjustment range of the detent release position can be as wide as that in the case of finely adjusting the attachment position of the proximity switch in the prior art. Moreover, the detent release position is reset only by performing an input operation for adjusting the threshold value T in the threshold adjustment unit 500, and the proximity switch mounting position is finely adjusted as in the prior art. Therefore, the adjustment work can be easily performed in a short time.

  According to the second aspect of the present invention, as shown in FIG. 7 (d), as the cylinder stroke position St changes, an upward convex peak and a downward convex peak are continuously generated from the cylinder stroke sensor detection signal. A detection signal S having a characteristic to be output is obtained.

  According to the third invention, as shown in FIG. 3, at least two (301, 302) cylinder stroke sensors 300 are arranged in the direction in which the cylinder stroke position St changes, as shown in FIG. 7 (d). By combining the detection signals S1 and S2 of the cylinder stroke sensors 301 and 302, a detection signal S having a characteristic of continuously outputting an upward convex peak and a downward convex peak can be obtained. .

According to the second and third inventions, it is possible to easily determine whether the cylinder rod 202 has moved to the expansion side or the contraction side without using other direction determination means. Moreover, the detent release position can be reset over a wide stroke range SA as in the first aspect of the invention, and the adjustment work can be easily performed in a short time.

  Hereinafter, embodiments will be described with reference to the drawings. In the embodiment, a wheel loader is assumed as a construction machine, and a cylinder stroke position measuring device mounted on the wheel loader will be described.

  As described in the prior art, as shown in FIG. 1 (a), the wheel loader 1 includes a boom cylinder (the boom cylinder for raising the boom 3 at the front of the vehicle body 2 and operating it in the boom lowering direction). In order to operate the lift cylinder) 4 and the bucket 5 in the tilt direction and the dump direction, a bucket cylinder (dump cylinder) 6 is provided.

FIG. 2 shows a configuration diagram of a cylinder stroke position measuring apparatus according to the embodiment.

As shown in FIG. 2, when the work machine operating lever 7 provided in the driver's seat is operated from the neutral position, the boom operating valve 8 and the bucket operating valve 9 are opened according to the operation. Then, pressure oil is supplied to the boom cylinder 4 and the bucket cylinder 6, and the boom 3 and the bucket 5 are operated.

The work machine operation lever 7 has a detent function. The detent function is a function for holding the work machine operation lever 7 at a predetermined operation stroke position.

Whether the detent function is maintained or released is determined by a signal S output from the magnetic force sensor 300 provided in the boom cylinder 4 and the bucket cylinder 6.

FIG. 3A shows the positional relationship between the cylinder 200 used as the boom cylinder 4 and the bucket cylinder 6 described above and the magnetic force sensor 300 as a cylinder stroke sensor in a longitudinal sectional view.

  As shown in FIG. 3A, a piston 201 is slidably provided on a cylinder tube 250 that is a wall of the cylinder 200. A rod 202 is attached to the piston 201. The rod 202 is slidably provided on the cylinder head 203. A chamber defined by the cylinder head 203, the piston 201, and the cylinder inner wall constitutes a cylinder head side oil chamber 204H. An oil chamber opposite to the cylinder head side oil chamber 204H via the piston 201 constitutes a cylinder bottom side oil chamber 204B.

  The cylinder tube 250 is formed with hydraulic ports 206H and 206B. Pressure oil is supplied to the cylinder head side oil chamber 204H via the hydraulic port 206H, or pressure oil is discharged from the oil chamber 204H via the hydraulic port 206H. Pressure oil is supplied to the cylinder bottom side oil chamber 204B via the hydraulic port 206B, or pressure oil is discharged from the oil chamber 204B via the hydraulic port 206B.

  The pressure oil is supplied to the cylinder head side oil chamber 204H and the pressure oil is discharged from the cylinder bottom side oil chamber 204B, whereby the rod 202 is retracted (moved toward the contraction side), or the cylinder head side oil chamber 204H. When the pressure oil is discharged from the cylinder and the pressure oil is supplied to the cylinder bottom side oil chamber 204B, the rod 202 extends (moves to the extension side). That is, the rod 202 moves linearly in the left-right direction in the figure.

A magnetic force sensor 300 as a cylinder stroke sensor is provided outside the cylinder tube 250.

  That is, the piston 201 is provided with a magnet 350 that generates lines of magnetic force. The magnet 350 is provided on the piston 201 so that the N pole and the S pole are arranged along the linear movement direction of the piston 201 and the rod 202. The magnet 350 may be provided on the piston 201 so that the N pole and the S pole are arranged along the direction perpendicular to the linear movement direction of the piston 201 and the rod 202.

The magnetic force sensor 300 includes two magnetic force sensors 301 and 302 that are spaced apart from each other by a predetermined distance along the linear movement direction of the piston 201. The magnetic sensors 301 and 302 detect the magnetic force (magnetic flux density) through the magnetic force lines generated by the magnet 350, and output an electric signal (voltage) S corresponding to the magnetic force (magnetic flux density). The magnetic sensors 301 and 302 are provided at known origin positions. Based on the detection results of the magnetic sensors 301 and 302, the measurement position obtained from the detection result of the rotation sensor 100 is reset to the origin position (reference position).
Further, as will be described later, a determination is made as to whether or not to maintain the detent function based on the signal S output from the reset sensor 300.

  As the magnetic sensors 301 and 302, for example, Hall ICs are used.

  The magnetic sensors 301 and 302 are attached to the eaves 310. The eaves 310 is a member that covers the magnetic force sensors 301 and 302. The eaves 310 are attached to the band 320. The band 320 is fixed to the outer periphery of the cylinder tube 250. The band 320 is made of a magnetic material. As a material of the band 320, a magnetic material that is usually easily available, such as a general structural steel material, can be used.

  FIG. 3B shows a cross-sectional view taken along line AA in FIG. 3A, that is, a cross-sectional view of the cylinder tube 250.

  The band 320 is fixed in pressure contact with the outer periphery of the cylinder tube 250. The band 320 includes a band member 320A having a semicircular cross section corresponding to the outer diameter of the cylinder tube 250, and a band member 320B having a semicircular cross section, and the band member 320A and the band member 320B are The cylinder tube 250 is pressed against the outer periphery by being fastened. One band member 320 </ b> A is provided with a cover 310 that covers the eaves 310 and the eaves 310. For this reason, the magnetic force sensors 301 and 302 can be fixed to the outer periphery of the cylinder tube 250 without forming a screw hole in the cylinder tube 250 or performing processing such as welding the outer periphery of the cylinder tube 250. Moreover, since it is not necessary to process and process the cylinder tube 250, the thickness of the cylinder tube 250 can be maintained at a minimum thickness. In other words, when the cylinder tube 250 is processed and processed, the tube itself must be thickened to maintain the strength, but this is not necessary.

  In addition, the fixing position of the band 320 to the cylinder tube 250 can be easily and easily changed, and the magnetic force sensors 301 and 302 can be placed at arbitrary positions in the longitudinal direction of the cylinder tube 250 (the linear movement direction of the piston 201 and the rod 202). Can be easily and easily installed. By simply changing the diameter of the band 320, the common magnetic sensor 300 can be attached to cylinders of any size, so that there is versatility and cost reduction can be achieved.

  FIG. 4 shows details of the configuration of the magnetic sensors 301 and 302, the eaves 310, the cover 390, and the band 320.

  FIG. 4A is an enlarged vertical sectional view of the cylinder tube 250 corresponding to FIG. 4B is an enlarged cross-sectional view of the cylinder tube 250 corresponding to FIG. 3B (view B in FIG. 3A).

    As shown in FIG. 4, the magnet 350 is fixed to the surface of the piston 201 facing the cylinder head side oil chamber 204 </ b> H by a holder ring 351.

  The magnet 350 is fixed to the piston 201 by fastening the holder ring 351 and the magnet 350 together with the piston 201.

  The eaves 310 are made of a magnetic material and are disposed so as to cover the magnetic force sensors 301 and 302. The eaves 310 can be made of a magnetic material that is usually readily available, such as carbon steel or general structural steel.

  The arrangement of the eaves 310 and the magnetic sensors 301 and 302 is symmetrical in the left-right direction in FIG. 4A and has the same positional relationship, and therefore, one magnetic sensor 301 will be described as a representative.

  The eaves 310 are fixed to the band member 320A.

  The magnetic sensor 301 is fixed to the eaves 310 so that the upper surface is covered with the eaves 310. Further, the bottom surface of the magnetic sensor 301 is in close contact with the outer peripheral surface of the cylinder tube 250.

  Although one magnetic sensor 301 has been described, the other magnetic sensor 302 is similarly attached to the eaves 310.

  The eaves 310 incorporates a terminal block 313 having terminals 312. A cover 390 is attached to the eaves 310 so as to cover the terminals 312 and 313.

A nipple 314 into which the harness 399 is inserted is connected to the eaves 310. The nipple 314 is coupled to a hydraulic hose 395 through which the harness 399 is inserted. The reason why the hydraulic hose is used is to reliably protect the harness 399 and improve reliability. The magnetic sensors 301 and 302 and the terminal 312 are connected by an electric signal line (not shown). Furthermore, a harness 399 is connected to the terminal 312 via the insertion holes of the hydraulic hose 390 and the nipple 314. This harness 399 is connected to the controller 400. In the controller 400, the detection signals S of the magnetic sensors 301 and 302 and the detection signal of the rotation sensor 100 are processed, and the stroke position of the rod 202 (piston 201) is measured. That is, the position of the rod 202 is measured from the detection result of the rotation sensor 100, and the measurement position of the rod 202 obtained from the detection result of the rotation sensor 100 is based on the detection result of the magnetic field sensors 301 and 302. Position).

Further, the controller 400 determines whether to maintain or release the detent function based on the signal S output from the magnetic force sensors 301 and 302.

(First example of magnetic sensor signal)
5A, 5B, and 5C show the relationship between the stroke position St of the rod 202 and the detection signal S (magnetic force or output voltage value) of the magnetic force sensors 301 and 302. FIG. 5A shows the detection signal S1 of the magnetic sensor 301, FIG. 5B shows the detection signal S2 of the magnetic sensor 302, and FIG. 5C shows the detection signal S1 of the magnetic sensor 301 and the magnetic sensor 302. The detection signal S is obtained by adding and synthesizing the detection signal S2. FIGS. 6A, 6 </ b> B, and 6 </ b> C schematically show how the rod 202 moves from the expansion side to the contraction side. As the rod 202 moves from FIG. 6 (a) through FIG. 6 (b) to FIG. 6 (c), the horizontal axis of FIG. 5 (a), (b), (c) is set to the right side (contraction side) in the figure. Shall be moved to.

  In this embodiment, when the magnet 350 is closest to the magnet 350 in FIG. 5A, the magnetic force sensor 301 that outputs a positive peak signal that is convex upward, and when the magnet 350 is closest to the magnet 350, FIG. A magnetic sensor 302 that outputs a peak signal having a negative polarity that is convex downward, that is, a polarity opposite to that of the magnetic sensor 301 is used.

In this way, the detection signals S1 and S2 are output from the two magnetic sensors 301 and 302, respectively, and the detection signals S1 and S2 are combined as shown in FIG. As it moves from the expansion side to the contraction side, it has a characteristic of continuously outputting a convex peak upward and a convex peak downward, or a peak convex downward as the rod 202 moves from the contraction side to the expansion side. Thus, a detection signal S (= (S1 + S2) / 2) having a characteristic of continuously outputting upward convex peaks is obtained.

In the present specification, the upwardly convex peak and the downwardly convex peak are a peak on the positive side of the base level of the signal S and a peak on the negative side of the base level of the signal S, respectively. is there.

(Second example of magnetic sensor signal)
7A, 7B, and 7C show the relationship between the stroke position St of the rod 202 and the detection signal S (magnetic force or output voltage value) of the magnetic force sensors 301 and 302. FIG. 7A shows the detection signal S1 of the magnetic sensor 301, FIG. 7B shows the detection signal S2 of the magnetic sensor 302, and FIG. 7C shows the detection signal S1 of the magnetic sensor 301 to the magnetic sensor 302. The detection signal S obtained by subtracting the detection signal S2 is shown. As the rod 202 moves from FIG. 6 (c) through FIG. 6 (b) to FIG. 6 (a), the horizontal axis of FIGS. Shall be moved to.

  In this embodiment, when the magnet 350 is closest to the magnet 350 in FIG. 7A, the magnetic force sensor 301 that outputs a positive peak signal that is convex upward, and the magnetic force sensor 302 that is closest to the magnet 350 are illustrated. 7 (b), a magnetic sensor 302 that outputs a positive peak signal having an upwardly convex polarity and outputs a negative peak signal having a downward convexity when the magnet 350 is closest to the location of the magnetic sensor 301 is used. Is done.

In this way, the detection signals S1 and S2 are output from the two magnetic sensors 301 and 302, respectively, and the detection signals S1 and S2 are combined as shown in FIG. 7C, that is, the detection signal S2 is subtracted from the detection signal S1 and averaged. Then, as the rod 202 moves from the contraction side to the extension side, a detection signal S (= (S1-S2) / 2) having a characteristic of continuously outputting a convex peak downward and a convex peak upward is obtained. It is done.

In the controller 400, the detection signal S of the magnetic force sensor 300 and the threshold value T are compared and a comparison result is output. The threshold value T is set as a cylinder stroke position corresponding to the detent release position.

As shown in FIG. 2, a monitor device 500 as a threshold adjustment unit is provided in a cab (operator's cab) of the wheel loader 1.

The monitor device 500 includes a monitor screen 501 and a threshold adjustment operator 502. When the threshold adjustment operator 502 is operated, the threshold value T changes in accordance with the operation amount, and the cylinder stroke position St corresponding to the detent release position changes accordingly. A state in which the threshold T and the detent release position are changed in accordance with the operation of the threshold adjustment operator 502 is displayed on the monitor screen 501. The operator can easily and accurately set a desired detent release position by operating the threshold adjustment operator 502 while viewing the display content of the monitor screen 501.

As shown in FIG. 5C or FIG. 7C, in the magnetic force sensor 300 that detects the cylinder stroke position St using magnetism as a medium, the peak peak width of the detection signal S is wide (broad). ), The magnitude of the threshold value T can be changed over a wide stroke range SA. For example, the threshold value T can be adjusted with a width of ± 30 mm in the stroke range SA. In addition, what is necessary is just to change the attachment position of the magnetic sensor 300, when it is desired to adjust a detent release position beyond this adjustment range.

(First algorithm)
FIG. 8 is a flowchart showing an algorithm executed by the controller 400 assuming the above-described “second example of magnetic sensor signal” (FIG. 7).

Hereinafter, processing performed by the controller 400 will be described with reference to FIG.

This first algorithm is based on the premise that it is determined whether the moving direction of the rod 202 is the expansion side or the contraction side. For example, it is possible to determine the direction by using a potentiometer provided on the working machine operating lever 7 or a hydraulic pressure signal (ppc pressure) for the boom operating valve 8 and the bucket operating valve 9. Further, as shown in FIG. 7C, a threshold value T corresponding to the detent release position is set on the upward convex peak side, and a threshold value A is set on the downward convex peak. This threshold value A is different from the threshold value T and is preset as a fixed value.

In this first algorithm, since the direction in which the rod 202 moves is determined, as shown in FIG. 7C, the threshold adjustment width SA is determined from the stroke position where the threshold A is set. This is the width up to the top of the peak of the convex peak.

First, the controller 400 determines whether or not the moving direction of the rod 202 is the extension side (step 101). As a result, if it is determined that the moving direction of the rod 202 is the extension side (YES in step 101), it is next determined whether or not the current detection signal S is equal to or less than the threshold value A. (Step 102). As a result, when it is determined that the moving direction of the rod 202 is the extension side and the current detection signal S is equal to or less than the threshold value A, the downward convex peak is reduced in FIG. In order to determine whether or not the threshold value T has been reached, it is determined whether or not the moving direction of the rod 202 is the extension side (step). 103). As a result, when it is determined that the moving direction of the rod 202 is the extension side (determination YES in step 103), it is next determined whether or not the current detection signal S has reached the threshold value T. (Step 104). As a result, when it is determined that the moving direction of the rod 202 is the extension side and the current detection signal S has reached the threshold value T, it is determined that the cylinder stroke position St has reached the detent release position. Then, processing for canceling the detent function is performed (step 105).

The controller 400 maintains the detent function when the height of the boom 3 is lower than a predetermined detent release position, that is, when the boom cylinder 4 is in a stroke on the extending side and the detection signal S is smaller than the threshold value T. Current i1 is output. Further, when the height of the boom 3 is equal to or higher than a predetermined detent release position, that is, when the boom cylinder 4 is in a stroke on the extending side and the detection signal S becomes equal to or higher than the threshold value T, the current i1 is turned off as detent release processing ( Step 105).

Therefore, when the operator operates the operating lever for work implement 7 in the boom raising direction and the detection signal S does not reach the threshold value T in the process shown in FIG. In this case, the current i1 is applied from the controller 400 to the solenoid 14 of the boom detent portion of the work machine operation lever 7 because the position is below the position. As a result, the solenoid 14 maintains the biased state, and the spool fixes the work machine operating lever 7 to a predetermined boom raising operation position. As a result, the boom 3 is raised while the work implement operating lever 7 is held at the predetermined boom raising position. When the operation lever 7 for the work implement is further operated in the boom raising direction and the detection signal S reaches the threshold value T in the processing shown in FIG. 8, the height of the boom 3 reaches the detent release position. Therefore, the controller 400 turns off the current i1, and the solenoid 14 is de-energized. As a result, the spool returns and the work machine operating lever 7 is returned to the neutral position, and the detent function is released (boom kickout).

The same applies to the bucket positioner.

In the process shown in FIG. 8 when the operator operates the work machine operating lever 7 in the bucket tilt direction, when the detection signal S does not reach the threshold value T, the bucket 5 is dumped from the predetermined detent release position. Since it is a case where it exists in a direction side, the electric current i2 for maintaining a detent function is output from the controller 400. FIG. Further, when the height of the bucket 5 is on the tilt direction side with respect to the predetermined detent release position, the current i2 output from the controller 400 is turned off.

Therefore, when the operator operates the work implement operating lever 7 in the tilt direction, in the process shown in FIG. 8, the detection signal S does not reach the threshold value T. Therefore, the current i2 is supplied from the controller 400 to the work implement. In addition to the solenoid 17 in the bucket detent portion of the operation lever 7, the solenoid 17 maintains the biased state, and the spool fixes the work implement operation lever 7 at a predetermined tilt operation position. As a result, the bucket 5 tilts while the work implement operating lever 7 is held at the predetermined tilt position. Then, when the operation lever 7 for the work implement is further operated in the bucket tilt direction and the detection signal S reaches the threshold value T in the processing shown in FIG. 8, the bucket 5 has reached the detent release position. Then, the current i2 output from the controller 400 is turned off, the solenoid 17 is de-energized, the spool is returned, the work machine operating lever 7 is returned to the neutral position, and the detent function is released (bucket positioner).

As described above, according to the present embodiment, the detent release position is set by setting the threshold value T with respect to the detection signal S of the magnetic force sensor 300. Therefore, the stroke range in which the threshold value T can be set. SA can be widened, whereby the detent release position adjustment range can be widened. In other words, the adjustment range of the detent release position can be as wide as that in the case of finely adjusting the attachment position of the proximity switch in the prior art. In addition, since the detent release position is reset only by operating the threshold adjustment operator 502 while setting the magnitude of the threshold T while looking at the monitor screen 501 of the monitor device 500, the conventional technique is used. As described above, it is not necessary to finely adjust the attachment position of the proximity switch. For this reason, adjustment work can be easily performed in a short time.

(Second algorithm)
In the first algorithm described above, it is determined whether the cylinder rod 202 has moved to the expansion side or the contraction side. However, as shown in FIG. 7D, if the threshold value T is set to the positive polarity side of the base level, it is not necessary to determine the direction in which the rod 202 moves. In the second algorithm, the threshold adjustment width SA is a width from the stroke position corresponding to the base level to the vicinity of the peak of the upwardly convex peak.

The second algorithm is illustrated in FIG.

That is, the controller 400 first determines whether or not the current detection signal S is equal to or less than the threshold value A (step 201). As a result, when it is determined that the current detection signal S is equal to or lower than the threshold value A, in FIG. 7 (d), the downward convex peak is set to the threshold value T from the contraction side toward the extension side. In order to determine whether or not the current detection signal S has been reached, it is determined whether or not the current detection signal S has reached the threshold value T (step 202). As a result, when it is determined that the current detection signal S has reached the threshold value T, it is determined that the cylinder stroke position St has reached the detent release position, and detent release processing is performed (step 103).

As described above, when the detection signal S has not reached the threshold value T, the controller 400 outputs the current i1 for maintaining the detent function. When the detection signal S reaches the threshold value T, the detent function is output. To release the current i1. Alternatively, as described above, when the detection signal S has not reached the threshold value T, the controller 400 outputs the current i2 for maintaining the detent function, and when the detection signal S reaches the threshold value T, The current i2 is turned off to cancel the detent function.

As described above, according to this embodiment, it is possible to easily determine whether the cylinder rod 202 has moved to the expansion side or the contraction side without using other direction determination means. In addition, as described in the first algorithm, the detent release position can be reset over a wide stalk range SA, and the adjustment operation can be easily performed in a short time.

In the above description, the detent function is canceled when the rod 202 moves to the extension side. However, depending on the construction of the work machine, the detent function is canceled when the rod 202 moves to the contraction side. May be. In this case, as shown in FIG. 7 (e), the threshold value A may be set on the upward convex peak side, and the threshold value T may be set on the downward convex peak side. In this case, in order to apply the first algorithm, in the first algorithm in FIG. 8, the determination in Step 101 is “Rod 202 moves to the contraction side?” And the determination in Step 103 is “Rod 202 contracts”. "Move to the side?"

  In the above description, the “second example of the magnetic sensor signal” (FIG. 7) has been described. However, the first algorithm and the second algorithm are similarly applied to the “first example of the magnetic sensor signal”. Can be applied.

  That is, as shown in FIG. 5C, the threshold value A is set for the downwardly convex peak, and the upwardly convex peak side is projected upward from the stroke position where the threshold value A is set. The first algorithm shown in FIG. 8 may be implemented after setting a threshold value T corresponding to the detent release position within the stroke range SA having a width up to the vicinity of the peak apex.

  Further, as shown in FIG. 5 (d), a threshold A is set for the downwardly convex peak, and the peak of the upwardly convex peak from the stroke position corresponding to the base level is set on the upwardly convex peak side. The second algorithm shown in FIG. 9 may be executed after setting a threshold value T corresponding to the detent release position in the stroke range SA having a width up to the vicinity.

When the rod 202 moves to the contraction side, if it is desired to cancel the detent function, as shown in FIG. 5E, a threshold value A is set on the peak side convex upward, and the peak side convex downward A threshold value T may be set for. In this case, in order to apply the first algorithm, in the first algorithm in FIG. 8, the determination in step 101 is “Is the moving direction of the rod 202 the contraction side?”, And the determination in step 103 is “Rod”. The movement direction of 202 is the contraction side?

  The above embodiment is based on the case where at least two (301, 302) magnetic sensor 300 are arranged in the direction in which the cylinder stroke position St changes as shown in FIG.

  However, one magnetic sensor 300 is provided in the cylinder 200, and the same processing can be performed based on the detection signal S output from one magnetic sensor 300.

  FIGS. 10A, 10 </ b> B, 10 </ b> C, and 10 </ b> D illustrate the detection signal S output from one magnetic sensor 300.

  10 (a) and 10 (b), similar to the detection signal S2 in FIG. 7 (b), detection of characteristics in which a convex peak and a convex peak are continuously output from one magnetic sensor. Signal S is shown. As shown in FIG. 10A, among the detection signals S output from one magnetic force sensor 300, a threshold value A is set at the peak on the rod contraction side and a threshold value T is set at the peak on the rod extension side. Then, when the rod 202 moves to the extension side, a process for canceling the detent function can be performed. In addition, as shown in FIG. 10B, a threshold value T is set at the peak on the rod contraction side of the detection signal S output from one magnetic force sensor 300, and the threshold value A is set at the peak on the rod extension side. Can be set to cancel the detent function when the rod 202 moves to the contraction side.

FIGS. 10C and 10D show a detection signal S having a characteristic having only an upwardly convex peak, similar to the detection signal S1 of FIG. 5A or FIG. 7A. As shown in FIG. 10C, when the threshold value T is set to a convex peak on the detection signal S output from one magnetic sensor 300 and the rod 202 moves to the extension side, the detent function is activated. Processing to cancel can be performed. Further, as shown in FIG. 10D, when the threshold T is set to a convex peak on the detection signal S output from one magnetic force sensor 300, the detent is moved when the rod 202 moves to the contraction side. Processing to cancel the function can be performed. Note that, similarly to the detection signal S2 of FIG. 5B, a threshold value is similarly set for the detection signal having a characteristic having a downwardly convex peak, and the same processing can be performed.

  In each of the above-described embodiments, the description has been made on the assumption that the detection medium is a magnet (magnetic force). However, the detection medium is not necessarily a magnet (magnetic force), and has a broad peak over a wide stroke range SA. Any detection medium that can output a detection signal may be used. For example, the present invention can be applied to a case where the detection medium is an ultrasonic wave and the ultrasonic sensor detects the ultrasonic wave.

FIGS. 1A, 1B, 1C, and 1D are diagrams illustrating the configuration of a wheel loader. FIG. 2 is a configuration diagram of a cylinder stroke position measuring apparatus according to the embodiment. 3A and 3B are views showing a longitudinal sectional view and a transverse sectional view of the cylinder, respectively. FIG. 4A is an enlarged view of a longitudinal sectional view of the cylinder tube corresponding to FIG. 3A, and FIG. 4B is a transverse section of the cylinder tube corresponding to FIG. It is the figure which expanded and showed the figure (A view of Fig.3 (a)). FIGS. 5A, 5 </ b> B, 5 </ b> C, 5 </ b> D, and 5 </ b> E are diagrams illustrating detection signals output from the magnetic sensor according to the embodiment. 6 (a), 6 (b), and 6 (c) are diagrams schematically showing the movement of the cylinder rod. FIGS. 7A, 7 </ b> B, 7 </ b> C, 7 </ b> D, and 7 </ b> E are diagrams illustrating detection signals output from the magnetic sensor according to the embodiment. FIG. 8 is a flowchart showing the first algorithm of the embodiment. FIG. 9 is a flowchart illustrating the second algorithm of the embodiment. FIGS. 10A, 10 </ b> B, 10 </ b> C, and 10 </ b> D are diagrams illustrating detection signals output from the magnetic sensor.

Explanation of symbols

  200 cylinder, 300 (301, 302) magnetic force sensor (cylinder stroke sensor), 400 controller (arithmetic processing unit), 500 monitoring device (threshold adjustment unit)

Claims (3)

A cylinder stroke position measuring device in a work machine for measuring a stroke position of a cylinder (200) of the work machine (1),
A cylinder stroke sensor (300) attached to the cylinder (200) for detecting the stroke position of the cylinder using magnetism as a medium;
An arithmetic processing unit (400) that compares a detection signal of the cylinder stroke sensor (300) with a threshold value and outputs a comparison result;
A cylinder stroke position measuring device in a work machine, comprising: a threshold adjustment unit (500) for performing an input operation for adjusting a threshold value. According to the change in the cylinder stroke position, the detection signal of the cylinder stroke sensor (300) can be used to obtain a detection signal with the characteristic of continuously outputting an upwardly convex peak and downwardly convex peak. The cylinder stroke position measuring device according to claim 1. At least two (301, 302) cylinder stroke sensors (300) are arranged in the direction in which the position of the cylinder stroke changes. By combining the detection signals of the cylinder stroke sensors (301, 302), the cylinder stroke sensor (300) protrudes upward. 2. A cylinder stroke position measuring apparatus for a working machine according to claim 1, wherein a detection signal having a characteristic of continuously outputting a peak of a peak and a peak protruding downward is obtained.

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