JP2015148573A - Control piston position detecting device and swash plate type variable capacity type hydraulic device using the same as well as manufacturing method of control piston position detecting device and control method of swash plate type variable capacity type hydraulic system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control piston position detecting device to which a non-contact type sensor can be attached without making any major changes to the conventional structure.SOLUTION: There is provided a rod 15 of which the hole portion is formed in the axis direction, attached to one end portion of a control piston 3 and reciprocated in the axial direction together with the control piston 3, a sleeve 19 made of metal with one end inserted into the hole portion of the rod 15 and the other end fixed to the rod 15, a probe 27 provided with a coil for generating a magnetic alternating field with one end inserted into the sleeve 19 and a detection unit 29 for detecting the axial position of the control piston 3 by the inductance change depending on the axial displacement of the sleeve 19 and the probe 27.

Description

  The present invention relates to a control piston position detection device, a swash plate type variable displacement hydraulic device including the same, a manufacturing method of the control piston position detection device, and a control method of the swash plate type variable displacement hydraulic device.

  A swash plate type variable displacement hydraulic pump, which is a kind of swash plate type variable displacement hydraulic device, continuously changes the discharge amount of pressure oil by controlling the tilt angle of the swash plate that gives axial displacement to each piston. Can be made. The tilt angle of the swash plate is controlled by a control device including an actuator that tilts the swash plate and a detection device that detects the tilt angle of the swash plate or the displacement amount of the actuator. Such a control device is integrally provided in the pump as described in Patent Documents 1 and 2 below.

  Patent Document 1 discloses a swash plate type variable displacement hydraulic pump that measures the displacement of a control piston as an actuator for driving a swash plate in a non-contact manner using an eddy current type gap sensor.

  Patent Document 2 discloses a swash plate type variable displacement hydraulic pump in which an annular permanent magnet is attached to a control piston as an actuator for driving a swash plate, and the displacement of the control piston is measured in a non-contact manner by a magnetostrictive method. Yes.

JP 2007-298011 A JP 2009-197709 A

  However, in both Patent Documents 1 and 2, there is a problem that it is necessary to process the control piston, and the piston having the conventional shape cannot be used as it is.

9 and 10 show a servo valve provided with a detection device that detects the axial position of a control piston 101 as an actuator for driving a swash plate (solid cam) by a linear potentiometer.
The control piston 101 is inserted into the cylinder of the cylinder block 103 and is reciprocated in the axial direction (left-right direction in the figure). When the control oil is supplied to the right cylinder chamber 105, the control piston 101 moves to the left. When the control oil is supplied to the left cylinder chamber 107, the control piston 101 moves to the right.

  A connecting portion 109 is fixed at the center of the control piston 101. A swash plate is connected to the connecting portion 109 via a link (not shown). Therefore, the tilt angle of the swash plate is changed by reciprocating the control piston 101 in the axial direction.

  A position detection rod 110 is fixed to one end of the control piston 101. The position detection rod 110 protrudes outside the cylinder chamber 105. As shown in FIG. 10, the tip end of the slider 112 a of the potentiometer 112 is locked to the protruding end 110 a of the position detection rod 110. The potentiometer 112 detects the position of the control piston 101 in the axial direction.

However, the detection of the position of the control piston 101 using the potentiometer 112 has the following problems.
First, since the potentiometer 112 (detection unit for detecting the position in the axial direction) is a contact type that comes into contact with the position detection rod 110, the potentiometer 112 is a semi-consumable item, and requires regular maintenance and replacement.
Further, since the potentiometer 112 is a contact type, the characteristics change due to winding resistance and brush (slider) wear.
Further, the potentiometer 112 has a plurality of portions to be soldered, and if there is a soldering failure, the operation may become unstable.
Further, since the potentiometer 112 is a voltage output, it is easily affected by disturbance noise.
From the above, another detection device that is non-contact is desired instead of the potentiometer 112. In addition, it is desired to change to a non-contact type sensor without greatly changing the conventional structure.

  The present invention has been made in view of such circumstances, and a control piston position detection device capable of attaching a non-contact type sensor without greatly changing the conventional structure, and a tilt provided with the control piston position detection device. It is an object of the present invention to provide a plate type variable displacement hydraulic device, a method of manufacturing a control piston position detecting device, and a control method of a swash plate type variable displacement hydraulic device.

In order to solve the above problems, a control piston position detecting device of the present invention, a swash plate type variable displacement hydraulic device including the same, a manufacturing method of the control piston position detecting device, and a control method of the swash plate type variable displacement hydraulic device Adopts the following means.
That is, the control piston position detecting device according to the present invention is housed in a cylinder block and inserted in a reciprocating manner in the axial direction, and attached to the end of the control piston and axially together with the control piston. A rod having a hole formed in the axial direction, a metal sleeve having one end inserted into the hole of the rod and the other end fixed to the rod, and one end of the rod A probe having a coil inserted inside the sleeve and generating an alternating magnetic field therein, and a detection for detecting an axial position of the control piston by an inductance change according to an axial displacement between the sleeve and the probe And a portion.

The displacement of the control piston is detected by a sleeve sensor including a metal sleeve and a probe inserted into the sleeve. The sleeve sensor detects the position by an inductance change with the metal sleeve in an alternating magnetic field generated by a coil in the probe, and detects the displacement of the control piston without contacting the sleeve and the probe, that is, the shaft. It can comprise by the non-contact type which the detection part and position detection rod which detect a direction position do not contact.
In the present invention, the sleeve sensor can be configured with a simple configuration in which the sleeve of the sleeve sensor is inserted into and fixed to the hole of the rod attached to the end of the control piston. Thus, since it is not necessary to process or change the control piston, a sleeve sensor that is a non-contact sensor can be attached without greatly changing the conventional structure.
In particular, since there are many methods for detecting the displacement of the rod with a potentiometer provided with a rod as a detection shaft at the end of the control piston, a hole is formed in the rod having the same outer diameter as this rod. If the sleeve sensor is configured by inserting and fixing the sleeve in the part, the detection device can be changed from a contact type using a potentiometer to a non-contact type using a sleeve sensor.

  In the control piston position detecting device of the present invention, a rod-side male thread portion is formed on the outer peripheral surface of the end portion of the rod in which the hole portion is formed, and a sleeve is formed on the outer peripheral surface of the other end of the sleeve. A side male screw portion is formed, and an axial position adjusting nut is provided in which a female screw portion coupled to the rod side male screw portion and the sleeve side male screw portion is formed on an inner peripheral surface. .

  The rod and the sleeve are fixed by screwing to an axial position adjusting nut. Since the rod and the sleeve can move in the axial direction by rotating with respect to the axial position adjusting nut, the relative position between the rod and the sleeve can be changed. This facilitates adjustment of the zero point position of the sleeve sensor.

  The swash plate type variable displacement hydraulic device of the present invention includes a cylinder barrel that rotates about a rotation axis, a plurality of axial cylinders formed at predetermined intervals in the circumferential direction of the cylinder barrel, And a plurality of axial pistons inserted in a reciprocating manner, and a swash plate that contacts and slides on an end of each axial piston to determine an axial displacement of each axial piston. A displacement hydraulic device main body and a control device having the control piston position detection device described in any of the above are provided.

Since any one of the above-described control piston position detection devices is provided, a swash plate type variable displacement hydraulic device including a non-contact type sleeve sensor can be provided.
Typical examples of the swash plate variable displacement hydraulic device include a swash plate variable displacement hydraulic pump and a swash plate variable displacement hydraulic motor.

  Further, the manufacturing method of the control piston position detecting device of the present invention includes a cylinder barrel that rotates about a rotation axis, a plurality of axial cylinders formed at a predetermined interval in a circumferential direction of the cylinder barrel, and each of the axial cylinders Used in a swash plate type variable displacement hydraulic device including a piston inserted in a reciprocating manner and a swash plate that contacts and slides on an end of each piston to determine axial displacement of each piston. A method of manufacturing a control piston position detecting device for detecting an axial position of a control piston for determining a tilt angle of the swash plate, the rod hole forming step for forming a hole in the axial direction of the rod, and the control A rod mounting step of attaching the rod to one end of the control piston so as to reciprocate in the axial direction together with the piston; and inserting one end into the hole of the rod and the other end A sleeve mounting step for fixing a metal sleeve to the rod, and one end of a probe having a coil for generating an alternating magnetic field inside is inserted into the sleeve so that the sleeve can be moved relative to the sleeve. A probe attaching step, and a detecting portion attaching step for attaching a detecting portion for detecting an axial position of the control piston by an inductance change according to an axial displacement between the sleeve and the probe. .

The sleeve sensor can be configured by a simple process of inserting and fixing the sleeve of the sleeve sensor into the hole of the rod attached to the end of the control piston.
In particular, since there are many methods for detecting the displacement of the rod with a potentiometer provided with a rod as a detection shaft at the end of the control piston, a hole is formed in the rod having the same outer diameter as this rod. If the sleeve sensor is configured by inserting and fixing the sleeve in the part, the detection device can be changed from a contact type using a potentiometer to a non-contact type using a sleeve sensor.

  Furthermore, in the manufacturing method of the control piston position detecting device of the present invention, a locking claw attaching step of attaching a locking claw to one end of the control piston, and a neck portion locked to the locking claw at the tip of the rod A neck forming step to be formed; a rod inserting jig attaching step for attaching a rod inserting jig for forming an outer diameter surface connected to the outer diameter of the rod by being attached so as to fill the neck; and the control piston reciprocates. An O-ring attaching step of attaching an O-ring to a hole opening in the cylinder to be performed; a rod inserting step of inserting the rod into the hole portion; and a rod inserting jig removing step of removing the rod inserting jig; It is characterized by having.

  A rod formed on one end of the rod is locked to a locking claw attached to the control piston, whereby the rod is fixed to the control piston. When this rod is inserted into the cylinder in which the control piston reciprocates, it is necessary to insert it into the opening of the cylinder. However, since an O-ring for sealing is provided at the opening of the cylinder, the corner of the neck formed on the rod may come into contact with the O-ring and damage or cut the O-ring. . Therefore, in the present invention, a rod insertion jig is formed that fills the neck of the rod and forms an outer diameter surface connected to the outer diameter of the rod before insertion into the opening. Thereby, when inserting a rod in an opening part, a corner | angular part does not hit and an O-ring is damaged.

  Further, the control method of the swash plate type variable displacement hydraulic device is obtained by a tilt angle detecting step of detecting a tilt angle of the swash plate as an axial position of the control piston, and the tilt angle detecting step. And a feedback control step of performing feedback control for controlling the axial position of the control piston so as to obtain a desired tilt angle.

  Since control is performed using the swash plate type variable displacement hydraulic device, the axial position of the control piston can be obtained using a non-contact sensor, and the tilt angle of the swash plate is accurately feedback controlled. can do.

  Since the sleeve sensor can be configured with a simple configuration in which the sleeve of the sleeve sensor is inserted and fixed in the hole of the rod attached to the end of the control piston, a large change is made to the conventional structure. A sleeve sensor that is a non-contact type sensor can be attached without any problem.

It is the longitudinal section showing the important section of the control device of the swash plate type variable capacity type hydraulic pump concerning one embodiment of the present invention. It is the longitudinal cross-sectional view which expanded and showed the position detection rod periphery of FIG. 1A and 1B show a fixing structure of the tip of the position detection rod of FIG. 1, FIG. It is the longitudinal cross-sectional view which showed typically the relationship with the position detection rod of FIG. 1, a sleeve, and a probe. The sleeve sensor provided with the sleeve and the probe is shown, (a) is a side view showing a state in which most of the probe is accommodated in the sleeve, (b) is the tip of the probe is accommodated in the sleeve It is the side view which showed the state which exists. FIG. 2 is a control block diagram illustrating control of a hydraulic pump performed using the control device illustrated in FIG. 1. The assembly method at the time of inserting the front-end | tip of a position detection rod into the hole of a flange is shown, (a) is the side view which showed the state which fits a ring body in the neck part of the front-end | tip of a position detection rod, and shows insertion. FIG. 3 is a front view showing a ring body divided into two. 1 is a longitudinal sectional view showing a swash plate type variable displacement hydraulic pump according to an embodiment of the present invention. It is the longitudinal cross-sectional view which showed the servo valve which performs position detection by a potentiometer. It is AA sectional drawing of FIG.

Embodiments according to the present invention will be described below with reference to the drawings.
A swash plate type variable displacement hydraulic pump (hereinafter simply referred to as “hydraulic pump”) according to the present embodiment is mounted on a cable laying ship and used for a cable engine used for laying and winding a submarine cable, for example. . The pressure oil discharged by the hydraulic pump rotates the drum that winds and feeds the submarine cable.

FIG. 8 is a longitudinal sectional view showing the entire hydraulic pump. The hydraulic pump includes a control device 1 and a hydraulic pump body 2.
The hydraulic pump body 2 includes a cylinder barrel 8 disposed inside the casing 6, a swash plate (solid cam) 12, a valve plate 14, an auxiliary pump 18 fixed to the outside of the casing 6, and the like.

  The cylinder barrel 8 is supported via a spline on a rotating shaft 20 that is rotatably supported in a bearing hole that penetrates the casing 6 via bearings 22, 22, and is connected to an end of the rotating shaft 20 (not shown). Driven and rotated together with the rotary shaft 20 by a drive source (such as an electric motor or an internal combustion engine). A plurality of axial cylinders 60 are bored in the cylinder barrel 8 at equal intervals in the circumferential direction, and pistons (axial pistons) 61 are fitted in the axial cylinders 60 so as to reciprocate.

  The base end portion of each piston 61 is connected to a shoe 63 through a ball joint 62. Each shoe 63 is held in contact with and slidable with respect to the swash plate 12 by a ball retainer 64 and a retainer 65 which are externally fitted to the cylinder barrel 8 and urged by a spring 66. An axial displacement corresponding to the 12 tilt angles and the rotation angle phase of the cylinder barrel 8 is given to each piston 61.

  In the swash plate 12, the arcuate guided surfaces 74 formed on both sides of the rotary shaft 20 are engaged with the inner arc-shaped guide surfaces 24 formed on the casing 6 with the rotary shaft 20 passing through the center. It is supported so as to be in contact with and slidable, and can be tilted about a tilting shaft 67 perpendicular to the paper surface of FIG. A connecting portion 71 extends from the end of the swash plate 12 on the control device 1 side, and one end of a link 72 is rotatably connected to the connecting portion 71 by a pin 73. The other end is rotatably connected to a connecting portion 13 of a control piston 3 (see FIG. 1) described later by a pin 43.

  On the other hand, the end surface of the cylinder barrel 8 opposite to the swash plate 12 is pressed against the valve plate 14 by the bias of the spring 66. The valve plate 14 is provided with two arc-shaped ports 81, 82, one port 81 communicating with an intake port (not shown) for sucking oil, and the other port 82 discharging oil. It communicates with a discharge port (not shown).

  Further, each axial cylinder 60 of the cylinder barrel 8 is communicated with an end face pressed against the valve plate 14 via an individual passage, and each port according to each angular position as the cylinder barrel 8 rotates. The ports 81 and 82 are sequentially communicated, and the ports 81 and 82 are completely closed once and then the ports are switched.

  The auxiliary pump 18 is configured by a fixed displacement pump such as a gear pump, and the rotation shaft 91 is connected to the rotation shaft 20 of the hydraulic pump main body 2 via the coupling 26. Control oil is supplied to the servo valve 4 by the auxiliary pump 18.

  FIG. 1 shows a control device 1 for tilting the swash plate 12 (see FIG. 8). As shown in FIG. 8, the control device 1 is integrally connected to the hydraulic pump body 2. The control device 1 includes a control piston 3, an electrohydraulic servo valve 4 that switches an oil passage supplied to the control piston 3, and a cylinder block 5 that houses the control piston 3.

  The control piston 3 is inserted into a cylinder formed in the cylinder block 5 and is reciprocated in the axial direction (left-right direction in the figure). A left cylinder chamber 9a partitioned by a left flange 7a is formed on the left side of the control piston 3, and a right cylinder chamber 9b partitioned by a right flange 7b is formed on the right side of the control piston 3. A left oil passage 11a through which control oil is supplied and discharged is connected to the left cylinder chamber 9a, and a right oil passage 11b through which control oil is supplied and discharged is connected to the right cylinder chamber 9b. When the control oil is supplied to the left cylinder chamber 9a by switching the servo valve 4, the control piston 3 moves to the right, and when the control oil is supplied to the right cylinder chamber 9b, the control piston 3 moves to the right. It has become.

  A connecting portion 13 is fixed at the center of the control piston 3. A swash plate 12 (see FIG. 8) is connected to the connecting portion 3 via a link 72 (see FIG. 8). As a result, the tilt angle of the swash plate 12 is changed as the control piston 3 reciprocates in the axial direction.

As shown in FIG. 2, one end (left side in the drawing) 15 a of the position detection rod 15 is fixed to one end (right side in the drawing) of the control piston 3. Specifically, the position detection rod 15 is fixed by a locking member 16 screwed to one end of the control piston 3.
FIG. 3 shows an enlarged view of the one end 15a portion of the position detection rod and the locking member 16. As shown in FIG. The locking member 16 has a male screw portion 16e at one end (left side in the figure) and a locking portion 16a at the other end (right side in the figure). The locking portion 16a includes a first recess 16b penetrating in a direction perpendicular to the axis and having a bottom portion, and a second recess 16d sandwiched between locking claws 16c on both sides. As shown in FIG. 3B, the second recess 16d is formed to extend from one end to a midway position.
On the other hand, one end 15a of the position detection rod 15 is provided with a neck portion 15e formed to have a small diameter leaving a head portion 15d at the tip. By fitting so that the first recess 16b of the locking member 16 corresponds to the head portion 15d of the position detection rod 15, and the second recess 16d of the locking member 16 corresponds to the neck portion 15e of the position detection rod 15. The tip of the position detection rod 15 is locked by the locking claw 16c.

As shown in FIG. 2, the other end (right side in the figure) 15b of the position detection rod 15 passes through the right flange 7b and protrudes out of the right cylinder chamber 9b. That is, the other end 15b of the position detection rod 15 protrudes to a space in the housing 31 attached to the right side of the right flange 7b.
An O-ring 17 for sealing control oil is provided in the hole of the right flange 7b through which the position detection rod 15 is inserted.

  A hole 15c is formed in the position detection rod 15 along the axial direction. One end (left end in the figure) 19a of a sleeve 19 made of metal is inserted into the hole 15c. The other end 19 b of the sleeve 19 is fixed to the other end (right end in the drawing) 15 b of the position detection rod 15 via an origin adjustment nut (axial position adjustment nut) 21. Specifically, as shown in FIG. 4, the origin that is screw-coupled to the male thread formed on the other end 15 b of the position detection rod 15 and the male thread formed on the other end 19 b of the sleeve 19. The sleeve 19 is fixed to the position detection rod 15 by the adjustment nut 21. The origin adjustment nut 21 adjusts the relative position of the position detection rod 15 and the sleeve 19 in the axial direction. By adjusting the relative position, the origin (zero point) of a sleeve sensor described later is adjusted. . The zero point is adjusted by, for example, a position detection rod so that the output of the sleeve sensor becomes zero when the drum driven by the hydraulic pump is stopped, that is, when no hydraulic oil is discharged from the hydraulic pump. The relative position between the sleeve 15 and the sleeve 19 is adjusted by the origin adjusting nut 21.

The origin adjusting nut 21 and the position detection rod 15 and the sleeve 19 are fixed by positioning screws 23 and 23 that are screwed into radial thread grooves formed in the origin adjusting nut 21. The position detection rod 15 and the origin adjustment nut 21 are fixed by the tip of one positioning screw 23 coming into contact with the male screw portion of the position detection rod 15, and the tip of the other positioning screw 23 contacts the male screw portion of the sleeve 19. The sleeve 19 and the origin adjusting nut 21 are fixed by contact.
Further, in order to securely fix the position of the origin adjusting nut 21, the origin adjusting nut 21 is prevented from rotating by a lock nut 25 such as a hard lock nut (registered trademark).

  As shown in FIGS. 1, 2, and 4, a probe 27 is inserted into the inner hole of the sleeve 19. Specifically, the tip 27a of the probe 27 is inserted from the other end 19b side of the sleeve 19, and the sleeve 19 and the probe 27 have a predetermined gap in the radial direction, and are not in contact with each other. It has become. The probe 27 has a long and narrow bar shape, and a coil (not shown) for generating an alternating magnetic field is provided therein. The base end portion 27 b of the probe 27 is fixed to a detection unit 29 that detects an output signal from the probe 27 and detects the position of the control piston 3. The detection unit 29 is fixed to the inside of the housing 31 connected to the main body of the control device 1 via a bracket 33. Further, it is preferable to use a high frequency magnetic field of 1 kHz or more as the magnetic field inside the probe 27. This is because the accuracy of displacement detection is further improved by using a high-frequency magnetic field.

  As shown in FIG. 5, the sleeve 19, the probe 27, and the detection unit 29 constitute a sleeve sensor. The sleeve sensor detects the axial position by an inductance change with the metal sleeve 19 in an alternating magnetic field generated by a coil in the probe 27. That is, different outputs can be obtained in accordance with the position where the relative position between the probe 27 and the sleeve 19 changes in the axial direction from FIG. 5 (a) to FIG. 5 (b). As an output, it is preferable to use a current output having resistance against disturbance noise. That is, when a noise voltage is applied to the voltage signal transmission line, the received voltage appears in a form in which the voltage signal is applied with noise. For example, if a 10V noise voltage rides on a 0-10V transmission line, the received voltage will be 20V (Max). In the case of current signals, the impedance of the circuit is low, and the resistance of the converter viewed from the output terminal of the current output type converter is usually 1 MΩ or more. In other words, the value of the current that flows through the circuit due to the noise voltage of 10 V is I = 10/10 ^ 6 = 10 ^ -5 = 0.01 mA from Ohm's law (V = IR). In other words, the noise is less than 1/2000 of the signal 20 mA, and the signal does not cause any problem in measurement.

  Thus, the position detection rod 15 fixed to the control piston 3 and the sleeve sensor (the sleeve 19, the probe 27, and the detection unit 29) constitute a control piston position detection device.

FIG. 6 is a control block diagram for controlling the hydraulic pump using the control device 1 described above.
First, the discharge amount corresponding to the set speed of the drum rotated by the hydraulic pump is input as an input signal at the console. The input signal is amplified by the servo amplifier 35 and input to the servo valve 4. Control oil is supplied to the servo valve 4, and the control oil is supplied to the control piston 3 via predetermined oil passages 11 a and 11 b (see FIG. 1) in response to an input signal from the servo amplifier 35. As a result, when the control piston 3 is displaced in the axial direction, the tilt angle of the swash plate 12 connected to the connecting portion 13 (see FIG. 1) changes accordingly, and the discharge amount from the hydraulic pump changes. The axial position of the control piston 3 is measured by the above-described sleeve sensors 19, 27 and 29, and this detection output is fed back to an input signal to the servo amplifier 35. Feedback control is performed until the deviation between the input signal to the serve amplifier 35 and the detection outputs of the sleeve sensors 19, 27, 29 becomes zero.

Next, an assembly method when the position detection rod 15 is inserted into the hole of the right flange 7b that partitions the right cylinder chamber 9b will be described with reference to FIG.
As already described with reference to FIGS. 1 and 2, an O-ring 17 for sealing control oil is provided in the hole of the right flange 7b. On the other hand, as described with reference to FIG. 3, the end 15a of the position detection rod 15 is provided with a corner portion by forming the neck portion 15e. As shown in FIG. 7A, a ring body (rod insertion jig) 40 is fitted to the neck portion 15e. As shown in FIG. 7B, the ring body 40 is divided into two parts, and an annular shape is formed by combining them. By fitting this ring body 40 into the neck portion 15e of the position detection rod 15, the recess formed by the neck portion 15e is filled to form an outer diameter surface continuous with the outer diameter of the position detection rod 15. In this state, the O-ring is not damaged by inserting the one end 15a of the position detection rod 15 into the hole of the right flange 7b. After inserting the position detection rod 15 into the hole of the right flange 7b, the ring body 40 is removed. Thereafter, the neck portion 15e of the position detection rod 15 is locked to the locking claw 16c of the locking member 16 as shown in FIG.

As described above, according to the hydraulic pump of the present embodiment, the following operational effects can be obtained.
The sleeve sensor can be configured with a simple configuration in which the sleeve 19 is inserted and fixed in the hole 15c of the position detection rod 15 attached to the end of the control piston 3. Thus, since it is not necessary to process or change the control piston 3, a sleeve sensor which is a non-contact sensor can be attached without greatly changing the conventional structure.
In particular, there are many methods (see FIGS. 9 and 10) in which a position detection rod is provided at the end of the control piston 3 and the displacement of the position detection rod is detected by a potentiometer. If a sleeve sensor is configured by forming a hole in the position detection rod and inserting and fixing a sleeve in the hole, the contact type using a potentiometer is changed to the non-contact type using a sleeve sensor. And the detection device can be easily changed.

  The position detection rod 15 and the sleeve 19 are fixed by screwing to the origin adjusting nut 21. Since the position detection rod 15 and the sleeve 19 can move in the axial direction by rotating with respect to the origin adjustment nut 21, the relative position between the origin position rod 15 and the sleeve 19 can be changed. It becomes possible. This facilitates adjustment of the zero point position of the sleeve sensor.

  Before the position detection rod 15 is inserted into the hole of the right flange 7b, the ring body 40 that fills the neck portion 15e and forms an outer diameter surface connected to the outer diameter of the position detection rod 15 is attached. When the position detecting rod 15 is inserted into the hole, the corner formed by the neck 15e does not hit and damage the O-ring.

Although the present embodiment has been described on the assumption that it is applied to a hydraulic pump, it can be applied to a hydraulic motor.
Moreover, although demonstrated as a use which drives the drum of a cable engine, it is not limited to this use, Other uses may be sufficient.

1 Control Device 3 Control Piston 4 Servo Valve 5 Cylinder Block 6 Casing 8 Cylinder Barrel 12 Swash Plate 14 Valve Plate 15 Position Detection Rod (Rod)
16 Locking member 17 O-ring 18 Auxiliary pump 19 Sleeve 20 Rotating shaft 21 Origin adjustment nut (axial position adjustment nut)
27 Probe 29 Detection unit 31 Housing 40 Ring body (rod insertion jig)
61 Piston (Axial Piston)

In order to solve the above problems, a control piston position detecting device of the present invention, a swash plate type variable displacement hydraulic device including the same, a manufacturing method of the control piston position detecting device, and a control method of the swash plate type variable displacement hydraulic device Adopts the following means.
That is, the control piston position detecting device according to the present invention is housed in a cylinder block and inserted in a reciprocating manner in the axial direction, and attached to the end of the control piston and axially together with the control piston. A rod having a hole formed in the axial direction, a metal sleeve having one end inserted into the hole of the rod and the other end fixed to the rod, and one end of the rod together it is inserted into the sleeve, and a probe having a coil for generating a magnetic field therein, detection for detecting the axial position of the control piston by the inductance change corresponding to axial displacement of the sleeve and the probe And a portion.

The displacement of the control piston is detected by a sleeve sensor including a metal sleeve and a probe inserted into the sleeve. The sleeve sensor is for detecting the position by the inductance change in the metallic sleeve in the magnetic field that occur by the coil in the probe to detect without the displacement of the control piston in contact with the sleeve and the probe, i.e. It can comprise by the non-contact type which the detection part and position detection rod which detect an axial direction position do not contact.
In the present invention, the sleeve sensor can be configured with a simple configuration in which the sleeve of the sleeve sensor is inserted into and fixed to the hole of the rod attached to the end of the control piston. Thus, since it is not necessary to process or change the control piston, a sleeve sensor that is a non-contact sensor can be attached without greatly changing the conventional structure.
In particular, since there are many methods for detecting the displacement of the rod with a potentiometer provided with a rod as a detection shaft at the end of the control piston, a hole is formed in the rod having the same outer diameter as this rod. If the sleeve sensor is configured by inserting and fixing the sleeve in the part, the detection device can be changed from a contact type using a potentiometer to a non-contact type using a sleeve sensor.

Further, the manufacturing method of the control piston position detecting device of the present invention includes a cylinder barrel that rotates about a rotation axis, a plurality of axial cylinders formed at a predetermined interval in a circumferential direction of the cylinder barrel, and each of the axial cylinders Used in a swash plate type variable displacement hydraulic device including a piston inserted in a reciprocating manner and a swash plate that contacts and slides on an end of each piston to determine axial displacement of each piston. A method of manufacturing a control piston position detecting device for detecting an axial position of a control piston for determining a tilt angle of the swash plate, the rod hole forming step for forming a hole in the axial direction of the rod, and the control A rod mounting step of attaching the rod to one end of the control piston so as to reciprocate in the axial direction together with the piston; and inserting one end into the hole of the rod and the other end A sleeve mounting step of fixing the metal sleeve against serial rod, one end of the probe with a coil for generating a magnetic field therein is inserted into the interior of the sleeve, relatively movable placed against the sleeve A probe attaching step, and a detecting portion attaching step for attaching a detecting portion for detecting an axial position of the control piston by an inductance change according to an axial displacement between the sleeve and the probe. .

As shown in FIGS. 1, 2, and 4, a probe 27 is inserted into the inner hole of the sleeve 19. Specifically, the tip 27a of the probe 27 is inserted from the other end 19b side of the sleeve 19, and the sleeve 19 and the probe 27 have a predetermined gap in the radial direction, and are not in contact with each other. It has become. Probe 27 is an elongated bar shape, a coil (not shown) is provided therein for generating a magnetic field. The base end portion 27 b of the probe 27 is fixed to a detection unit 29 that detects an output signal from the probe 27 and detects the position of the control piston 3. The detection unit 29 is fixed to the inside of the housing 31 connected to the main body of the control device 1 via a bracket 33. Further, it is preferable to use a high frequency magnetic field of 1 kHz or more as the magnetic field inside the probe 27. This is because the accuracy of displacement detection is further improved by using a high-frequency magnetic field.

As shown in FIG. 5, the sleeve 19, the probe 27, and the detection unit 29 constitute a sleeve sensor. The sleeve sensor detects the axial position by the inductance change of the metal sleeve 19 in the magnetic field that occur by the coil in the probe 27. That is, different outputs can be obtained in accordance with the position where the relative position between the probe 27 and the sleeve 19 changes in the axial direction from FIG. 5 (a) to FIG. 5 (b). As an output, it is preferable to use a current output having resistance against disturbance noise. That is, when a noise voltage is applied to the voltage signal transmission line, the received voltage appears in a form in which the voltage signal is applied with noise. For example, if a 10V noise voltage rides on a 0-10V transmission line, the received voltage will be 20V (Max). In the case of a current signal, the impedance of the circuit is low, and the resistance of the converter viewed from the output terminal of the current output type converter is usually 1 MΩ or more. In other words, the value of the current that flows through the circuit due to the noise voltage of 10 V is I = 10/10 ^ 6 = 10 ^ -5 = 0.01 mA from Ohm's law (V = IR). In other words, the noise is less than 1/2000 of the signal 20 mA, and the signal does not cause any problem in measurement.

Claims (6)

A control piston housed in a cylinder block and inserted so as to be capable of reciprocating in the axial direction;
A rod attached to an end of the control piston, reciprocating in the axial direction together with the control piston, and having a hole formed in the axial direction;
A metal sleeve having one end inserted into the hole of the rod and the other end fixed to the rod;
A probe having one end inserted into the sleeve and a coil that generates an alternating magnetic field therein;
A detection unit for detecting an axial position of the control piston by an inductance change according to an axial displacement between the sleeve and the probe;
A control piston position detecting device comprising: On the outer peripheral surface of the end of the rod where the hole is formed, a rod-side male thread is formed,
A sleeve-side male thread portion is formed on the outer peripheral surface of the other end of the sleeve,
2. The control according to claim 1, further comprising an axial position adjustment nut having an internal peripheral surface formed with an internal thread portion that is screwed into the rod-side external thread portion and the sleeve-side external thread portion. Piston position detection device. A cylinder barrel that rotates about a rotation axis;
A plurality of axial cylinders formed at predetermined intervals in the circumferential direction of the cylinder barrel;
A plurality of axial pistons removably inserted into each of the axial cylinders;
A swash plate type variable displacement hydraulic device main body having a swash plate that contacts and slides on an end of each axial piston and determines an axial displacement of each axial piston;
A control device having the control piston position detection device according to claim 1;
With
A swash plate type variable displacement hydraulic device characterized in that an inclination angle of the swash plate is determined by an axial position of the control piston. A cylinder barrel that rotates about a rotation axis, a plurality of axial cylinders formed at predetermined intervals in the circumferential direction of the cylinder barrel, pistons that are reciprocally inserted into the axial cylinders, and the pistons The axial direction of the control piston that determines the tilt angle of the swash plate is used in a swash plate type variable displacement hydraulic device having a swash plate that contacts and slides on the end of the swash plate to determine the axial displacement of each piston. A method of manufacturing a control piston position detecting device for detecting a position,
A rod hole forming step for forming a hole in the axial direction of the rod;
A rod attachment step of attaching the rod to one end of the control piston so as to reciprocate in the axial direction together with the control piston;
A sleeve attachment step of inserting one end into the hole of the rod and fixing the metal sleeve to the rod at the other end;
One end of a probe having a coil that generates an alternating magnetic field therein is inserted into the sleeve, and a probe mounting step is installed so as to be relatively movable with respect to the sleeve;
A detecting unit mounting step of mounting a detecting unit that detects the axial position of the control piston by an inductance change according to an axial displacement of the sleeve and the probe;
The manufacturing method of the control piston position detection apparatus characterized by the above-mentioned. A locking claw attachment step of attaching a locking claw to one end of the control piston;
A neck forming step of forming a neck locked to the locking claw at the tip of the rod;
A rod insertion jig attaching step for attaching a rod insertion jig for forming an outer diameter surface connected to the outer diameter of the rod by being attached so as to fill the neck portion;
An O-ring attachment step of attaching an O-ring to a hole opening in a cylinder in which the control piston reciprocates;
A rod insertion step of inserting the rod into the hole;
A rod insertion jig removing step for removing the rod insertion jig;
The manufacturing method of the control piston position detection apparatus of Claim 4 characterized by the above-mentioned. A control method for a swash plate type variable displacement hydraulic device according to claim 3,
A tilt angle detecting step of detecting a tilt angle of the swash plate as an axial position of the control piston;
A feedback control step for performing feedback control for controlling the axial position of the control piston so as to obtain a desired tilt angle using the tilt angle obtained by the tilt angle detecting step;
A control method for a swash plate type variable displacement hydraulic device.

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