阅读说明：本技术 利用角度传感器调节的位移控制 (Displacement control with angle sensor adjustment ) 是由 阿尼尔·巴拉萨赫·卡帕斯 尼尔玛吉特·库尔文达辛格·乔哈尔 桑贾伊·登达帕·马里 阿维纳什·达 于 2020-02-03 设计创作，主要内容包括：本发明题为“利用角度传感器调节的位移控制”。本发明公开了用于液压轴向位移机(诸如,泵和马达)的控制系统和反馈组件。控制系统和反馈组件可具有增强的可调节性。(The invention relates to a displacement control regulated by an angle sensor. The invention discloses a control system and feedback assembly for hydraulic axial displacement machines, such as pumps and motors. The control system and feedback assembly may have enhanced adjustability.)

1. A control system for controlling an angular position of a swash plate of an axial piston hydraulic pump or motor, the angular position of the swash plate being determined by servo pistons, the control system comprising:

valve means for providing a charging pressure to said servo pistons to cause said servo pistons to change said angular position of said swash plate;

a pivot arm configured to pivot about a pivot axis in coordination with movement of the servo piston, wherein an angular position of the pivot arm is indicative of the angular position of the swash plate, and wherein the pivot axis is adjustable at a position relative to a valve member and the servo piston;

a spring for transferring a spring load between the pivot arm and a valve member of the valve device; and

an angle sensor for sensing the angular position of the pivot arm, a housing of the angle sensor being angularly adjustable relative to the pivot arm about the pivot axis.

2. The control system of claim 1, further comprising a pivot shaft coupled to the pivot arm, the pivot shaft defining the pivot axis and adapted to pivot about the pivot axis in cooperation with the pivot arm, the control system further comprising a pivot axis adjustment sleeve rotatably mounted therein, the pivot axis adjustment sleeve mounted within a receptacle defined by a housing of a valve assembly, the pivot shaft being eccentric relative to the pivot axis adjustment sleeve such that rotation of the pivot axis adjustment sleeve relative to the housing of the valve assembly about its central axis adjusts a position of the pivot axis relative to the valve assembly and the servo piston.

3. The control system of claim 2, wherein the pivot axis adjustment sleeve is configured to be locked at a set rotational position about its central axis relative to the housing of the valve assembly once the pivot axis is in a predetermined position.

4. The control system of claim 3, wherein the pivot axis adjustment sleeve is locked in the set rotational position by a locking screw that laterally engages the pivot axis adjustment sleeve.

5. The control system of claim 3, wherein a plate is mounted to the housing of the angle sensor above the receptacle of the pivot axis adjustment sleeve, and wherein the angle sensor is mounted on the plate.

6. The control system of claim 5, wherein the angle sensor includes an angle sensing shaft extending through the plate and engaging the pivot shaft such that the angle sensing shaft and the pivot shaft are configured to rotate together about the pivot axis.

7. The control system of claim 6, wherein the pivot axis defines a receiver at one end for receiving an end of the angle sensing shaft, and wherein the angle sensing shaft and the receiver have matching non-circular cross-sectional shapes.

8. The control system of claim 6, wherein a sensor housing is mounted to the plate, and wherein the sensor housing is rotatably adjustable relative to the plate about the pivot axis, and wherein the sensor housing and associated internal sensing circuitry rotate relative to the angle sensing shaft, the angle sensor being set in an intermediate rotational sensing position relative to the pivot arm when the sensor housing is rotatably adjusted to allow the pivot arm to be in a position corresponding to an intermediate position of the swash plate.

9. The control system of claim 8, wherein the sensor housing is mounted to the plate with a fastener, wherein the sensor housing defines a fastener opening through which the fastener extends, and wherein the fastener opening is sized and shaped to allow a limited range of rotational movement of the sensor housing relative to the plate about the pivot axis before the fastener is fully tightened.

10. The control system of claim 9, wherein full tightening of the fastener rotationally locks the sensor housing in place relative to the plate.

11. The control system of claim 1, wherein the valve member comprises a spool moved by a solenoid.

12. The control system of any of claim 1, wherein the valve member is a first spool, wherein the valve arrangement includes a second valve spool coaxially aligned with the first valve spool along a valve axis, wherein a first solenoid and a second solenoid move the first spool and the second spool, respectively, along the valve axis, wherein a first end of the pivot arm is located between the first valve spool and the second valve spool, wherein a second end of the pivot arm is engaged with the servo piston, wherein the pivot axis is located between the first end and the second end of the pivot arm, wherein actuation of the first solenoid causes the servo piston to operate the pump or motor in a forward mode, and wherein actuation of the second solenoid causes the servo piston to operate the pump or motor in a reverse mode.

13. The control system of claim 12, wherein the position of the pivot axis is adjusted to move the pivot arm toward the first spool or toward the second spool to set the pivot arm at a position that achieves a balanced flow characteristic for both forward and reverse operation of the pump or motor.

14. The control system of claim 13, further comprising a first piston and a first spring between the first end of the pivot arm and the first spool, and a second piston and a second spring between the first end of the pivot arm and the second spool.

Background

In one example of a hydraulic axial displacement machine, such as an axial displacement pump or motor, the machine is operated by providing an input command signal (e.g., an electrical or hydraulic signal) from a control unit that provides hydraulic pressure to move one or more servo pistons along their displacement axis. In some examples, movement of one or more servo pistons is transferred to a swash plate, causing a change in the angle of the swash plate. The angular position of the swash plate determines the volumetric displacement produced by the axial displacement machine. When the swash plate is in the neutral position, i.e. perpendicular to the axis of movement of the servo pistons, the volume displacement is zero. The greater the inclination of the angular position of the swash plate with respect to the axis of movement of the servo pistons, the greater the volume displacement.

Typically, a feedback system provides information about the position of the swash plate at a given point in time to help regulate the machine and adjust the angular position of the swash plate so that the volumetric displacement (i.e., the angular position of the swash plate) coincides with the input control signal. Exemplary feedback systems are disclosed in U.S. patents 7,121,188 and 7,171,997.

Disclosure of Invention

In general, the present disclosure relates to a control system for a hydraulic axial displacement machine.

According to certain aspects of the present disclosure, the control system includes a feedback assembly that provides feedback information proportional to the position of the swash plate relative to the neutral position.

According to certain aspects of the present disclosure, the feedback information provided by the feedback assembly is proportional to a drive command signal, such as electrical or hydraulic.

In accordance with certain aspects of the present disclosure, a control system is disclosed that includes a forward motion module adapted to provide swashplate position information when a machine is driving forward fluid flow and a reverse motion module adapted to provide swashplate position information when the machine is driving reverse fluid flow.

Another aspect of the present disclosure relates to a control system for controlling an angular position of a swash plate of an axial piston hydraulic pump or motor. The angular position of the swash plate is determined by the servo pistons. The control system includes a valve arrangement for providing a charging pressure to the servo pistons to cause the servo pistons to change the angular position of the swash plate. The control system further comprises a pivot arm configured to pivot about a pivot axis in coordination with movement of the servo piston. The angular position of the pivot arm indicates the angular position of the swash plate. The pivot axis is adjustable in position relative to the valve member and the servo piston. The control system further includes an angle sensor for sensing an angular position of the pivot arm. The angle sensor is angularly adjustable relative to the pivot arm about a pivot axis. In some examples, the adjustability of the pivot axis allows the forward and reverse flow control characteristics to be balanced (e.g., symmetrical, balanced) so that the same magnitude of control signal produces the same flow rate regardless of whether the system is operating in forward or reverse. In some examples, an angle sensor senses the position of the swashplate and provides feedback to a master controller. The main controller detects a difference between a desired swash plate position based on an input command provided to the pump or motor and an actual swash plate position sensed by the angle sensor. The main controller then takes corrective action to move the swashplate to the desired position (e.g., the input signal may be modified or recalibrated until there is no error/difference output). The ability to adjust the angle sensor allows the angle sensor to be rotationally adjusted to a position where the intermediate position of the sensor is aligned with the pivot arm with the swash plate in the intermediate position. In this way, in the event of an angle sensor failure, the system can continue to operate under electrical proportional displacement control using the mechanical feedback provided by the pivot arm without an internal bias or spring load within the angle sensor compromising the balance/centering of the pivot arm.

While the control system and feedback assembly of the present disclosure will be described in connection with a hydraulic axial displacement machine, it should be understood that the principles disclosed herein may also be applied to other machines.

Various additional aspects will be set forth in the description set forth below. Aspects of the present invention relate to individual features and combinations of features. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the broad inventive concepts upon which the embodiments disclosed herein are based.

Drawings

The following drawings illustrate specific embodiments of the present disclosure and therefore do not limit the scope of the disclosure. The drawings are not necessarily to scale and are intended for use in conjunction with the description of the detailed description that follows.

FIG. 1 is a perspective view of a control system according to the principles of the present disclosure;

FIG. 2 is a cross-sectional view cut longitudinally through the control system of FIG. 1;

FIG. 3 is a cross-sectional view of the control system of FIG. 1 shown coupled to servo pistons for controlling the positioning of a swash plate of a hydraulic pump or motor;

FIG. 4 is a schematic diagram of the control system of FIG. 1 showing the servo pistons coupled to a swash plate for controlling the position of a hydraulic pump/motor;

FIG. 5 is another cross-sectional view of the control system of FIG. 1 showing an angle sensor coupled to a pivot arm of the control system;

FIG. 6 is a perspective view of a pivot shaft of the control system of FIG. 1;

FIG. 7 is a perspective view of a pivot axis adjustment sleeve of the control system of FIG. 1;

FIG. 8 is a perspective view of an angle sensor of the control system of FIG. 1;

FIG. 9 is a plan view of the angle sensor of FIG. 8;

FIG. 10 is a front view of the angle sensor of FIG. 8;

FIG. 11 is a graph illustrating flow rate versus signal amplitude for the angle sensor of FIG. 8;

FIG. 12 is a perspective view of another control system according to the principles of the present disclosure;

FIG. 13 is a cross-sectional view of the control system of FIG. 12 showing an angle sensor coupled to a pivot arm of the control system;

FIG. 14 is a perspective view of a pivot shaft of the control system of FIG. 12; and is

Fig. 15 is a perspective view of a pivot axis adjustment sleeve of the control system of fig. 12.

Detailed Description

Referring to fig. 1 and 2, a control system 102 for a hydraulic axial displacement machine (see, e.g., hydraulic machine 100 of fig. 4) is schematically illustrated. In some non-limiting examples, the axial displacement machine described herein includes a hydraulic motor or a hydraulic pump. Such hydraulic axial displacement machines may be used in a variety of apparatuses having hydraulic systems or hydraulic components, and the present disclosure is not limited to any particular type or types of apparatuses in which the hydraulic axial displacement machines described herein are implemented. The control system 102 includes a first control module 104 and a second control module 106. In some examples, the first control module and the second control module have the same configuration and include the same components. The first control module 104 controls forward motion of the servo piston 108. The second control module 106 controls the reverse motion of the servo piston 108.

Each control module 104, 106 includes a valve arrangement including a spool 110a, 110b, a spool actuator 112a, 112b (e.g., a solenoid), an input line 114a, 114b, and a charge pressure line 116a, 116b for charging the servo piston 108, a feedback piston 118a, 118b, and a feedback piston spring 120a, 120b, respectively. The two modules are coupled to the same pivot arm 122 (e.g., a feedback arm or link). The control module 104 is active during forward motion of the hydraulic machine 100 and the control module 106 is active during reverse motion of the hydraulic machine 100. In the exemplary control system 102, the feedback pistons 118a, 118b, the spools 110a, 110b, and the spool actuators 112a, 112b are coaxially aligned along a central axis A1. The servo pistons 108 are coupled to a swash plate 124 (FIG. 4) of the hydraulic machine 100. The pivot arm 122 includes a first portion 123 (e.g., a first end or end portion) positioned between the pistons 118a, 118b and a second portion 125 (e.g., a second end or end portion) that engages the servo piston 108. The pivot arm 122 pivots about pivot axis 127 in coordination with (e.g., in unison with) the movement of the servo piston 108. For example, movement of the servo piston 108 drives/causes pivotal movement of the pivot arm 122 about the pivot axis 127.

When neither spool 110a, 110b is actuated by its corresponding solenoid 112a, 112b, the housing pressure in the servo piston charge line 116a, 116b holds the swash plate 124 (fig. 4) in a neutral position. A charge signal is sent to either the forward moving solenoid 112a or the reverse moving solenoid 112b, actuating the respective spool 110a, 110b and causing the spool to move axially (along axis a1) toward its corresponding feedback spring 122a, 122 b. The spools move axially due to the force imparted by the corresponding solenoids 112a, 112 b. The actuated spools 110a, 110b move axially in proportion to the magnitude of the charging signal, thereby opening communication between the pressure input lines 114a, 114b and the servo piston charging lines 116a, 116b corresponding to the spools.

The charging pressure in the charging lines 116a, 116b causes the servo pistons to move in one direction corresponding to the actuated spools 110a, 110b, i.e., right or left in fig. 1 corresponding to forward or reverse movement of the machine 100, respectively.

Movement of the servo piston 108 causes the pivot arm 122 to pivot about the axis 127, thereby causing the feedback pistons 118a, 118b corresponding to the actuated spools to move in opposite directions (left or right) relative to the spring force provided by the corresponding feedback springs 120a, 120b of the feedback pistons 118a, 118 b. The desired swash plate angle is achieved when the axial force applied to the valve spool 110a, 110b by the solenoid 112a, 112b balances the axial force applied to the valve spool 110a, 110b by the corresponding feedback spring 120a, 120b of the corresponding feedback piston 118a, 118 b. The resulting axial spring force is proportional to the angle of the swash plate 124 relative to its neutral position.

When the charge signal on the solenoids 112a, 112b decreases or goes to zero, the actuation force on the corresponding spools 110a, 110b provided by the solenoids decreases and the force provided by the corresponding feedback springs 120a, 120b of the respective feedback pistons 118a, 118b pushes the spools 110a, 110b toward and ultimately to their neutral positions, thereby helping to return the spools 110a, 110b and the swash plate 124 to their neutral positions. The amount of axial movement of the valve spools 110a, 110b toward their respective feedback pistons 118a, 118b is proportional to the desired angle of the swashplate 124 relative to the neutral position of the swashplate 124.

The pivot arm 122 is not in direct contact with the valve spool 110a, 110b, but rather cooperates with the valve spool 110a, 110b via the corresponding feedback piston 118a, 118b and feedback spring 120a, 120 b. The feedback pistons 118a, 118b may provide a seat 140a, 140b for one axial end of the corresponding feedback springs 120a, 120b, respectively, with an opposite axial end of the feedback springs 120a, 120b abutting the spool-spring coupling 142a, 142 b. The spool-spring couplings 142a, 142b transmit axial forces between the corresponding spools 110a, 110b and their corresponding feedback springs 120a, 120 b.

The pivot arm 122 is configured to pivot about a pivot axis 127 in coordination with the movement of the servo piston 108. The angular position of the pivot arm 122 indicates the angular position of the swash plate. Pivot axis 127 is defined by a pivot shaft 150 coupled to pivot arm 122 by a cap bolt 152. The pivot arm 122 and pivot shaft 150 are configured to rotate together about pivot axis 127. The pivot axis 127 coincides with the longitudinal centerline of the pivot axis 150. The pivot shaft 150 is rotatably mounted within a pivot shaft adjustment sleeve 154. For example, the head 155 of the pivot shaft 150 is mounted for rotation within the sleeve 154, the shoulder 157 of the pivot shaft 150 rests on the lip 158 of the sleeve 154, and the shank 156 of the pivot shaft 150 extends through an opening in the sleeve 154. The pivot shaft 150 is eccentric relative to the sleeve 154. The sleeve 154 is mounted within a receptacle 160 defined by a housing 161 of the control system 102, which also supports the valve assembly. Due to the eccentricity of the pivot shaft 150, the position of the pivot axis 127 relative to the valve assembly and servo piston 108 can be adjusted by rotating the sleeve 154 about its central axis within the receptacle 160. The recess 163 in the end of the sleeve 154 may receive a tool for rotating the sleeve 154 within the receptacle. The position of the pivot axis 127 can be adjusted to properly center the pivot arm 122 between the pistons 118a, 118b to ensure balanced loading between the two modules. In this way, the valve arrangement provides the same flow for a given signal amplitude regardless of whether the system is operating in forward or reverse. The axis 127 is movable in a first direction 170 to increase the spring load at the first control module 104 and decrease the spring load at the second control module 106, and the axis is movable in a second direction 172 to increase the spring load at the second control module 106 and decrease the spring load at the first control module 104. Once the load has been balanced, the sleeve 154 may be locked in a set rotational position by a lateral set screw 176 engaging one side of the sleeve 154.

The control system 102 includes an arm angle sensor 200 (see fig. 1, 5, and 8-10), the sensor housing 201 of which is depicted as a component coupled to a board 165 mounted on an outer surface of the control housing 161. In one example, the angle sensor 200 is a rotary encoder having a sensor shaft 210 that rotates about its central axis relative to an internal sensing component within the sensor housing 201 that senses the degree of rotation. The sensor shaft 210 may be rotationally biased toward a neutral rotational sensing position by an angle sensor. The sensor housing 201 is mounted to the plate 165 in a manner that allows rotational adjustment of the rotational position of the housing 201 relative to the plate 165 about the central axis of the sensor shaft 210. For example, the housing 201 may be secured to the plate 165 by fasteners 220 (e.g., bolts, screws, etc.) that extend through openings 222 defined by the housing 201. The opening 222 may be oversized, elongated, or otherwise shaped to allow rotational adjustment of the housing 201. In the example shown, the opening 222 is a slot that curves around the sensor shaft 210. Once the housing has been set in the desired rotational position relative to the plate 165, the fasteners 220 may be fully tightened to lock the housing 201 in the selected rotational position.

A plate 165 covers the sleeve 154 and the receptacle 160. The sensor shaft 210 extends through the plate 165 and engages the pivot shaft 150. The center of the sensor shaft 210 is preferably aligned with the center of the pivot axis 150. Pivot shaft 150 and sensor shaft 210 are connected in a manner such that they rotate together about pivot axis 127. The sensor shaft 210 has an end with an elongated cross-section that fits or fits within a mating receptacle defined in one end of the pivot shaft 150. Thus, when the pivot arm 122 rotates about the pivot axis 127, the pivot axis 150 and the sensor shaft 210 also rotate about the pivot axis 127. The ability of the sensor housing 201 on the adjustment plate 165 allows the angle sensor to be rotationally adjusted so that the sensor shaft 210 is in a neutral position relative to the sensor's internal sensing components when the pivot arm 122 is in a position corresponding to the swash plate being in a neutral position. In this way, in the event of an angle sensor failure, the system can continue to operate under electrical proportional displacement control using the mechanical feedback provided by the pivot arm without an internal bias or spring load within the angle sensor compromising the balance/centering of the pivot arm 122.

The arm angle sensor 200 is adapted to detect the pivoting of the feedback arm and provide a signal corresponding to the pivoting angle to the main controller. The master controller is configured to compare the sensed pivot angle with an electric drive command signal (or other drive command signal, such as a hydraulic drive command signal) for driving the servo piston 108. In the event of a discrepancy between the sensed pivot angle and the command signal, the master controller is adapted to provide an error correction signal to the appropriate solenoid or other spool actuator 112a, 112b to compensate for the discrepancy and thereby achieve the desired angle of the swashplate 124 (FIG. 4). Thus, the controller is operatively coupled to the solenoids 112a, 112b, and is thereby adapted to send control signals to the solenoids 112a, 112 b. FIG. 11 is a graph showing flow rate versus feedback signal amplitude. The sensor feedback signal amplitude is in the range of 0-5 volts. The neutral position of sensor 200 is set to 2.5 volts. 0-2.5 volts represents feedback in the forward mode of operation, while 2.5-5.0 volts represents feedback in the reverse mode of operation.

In some examples, the controller 522 includes or is operably coupled to a processor that executes computer readable instructions stored on a memory, wherein execution of the computer readable instructions causes the controller 522 to provide control signals needed to correct for a difference between a desired angle and an actual angle of the swash plate, and not provide a correction signal without the difference or less than a predetermined maximum threshold difference.

In the example shown, the pivot arm 122 is biased between two coaxially aligned spools. In other examples, the pivot arm may be spring biased relative to a non-coaxially aligned valve spool or other valve component. For example, the valve spools may be parallel and side-by-side with respect to each other, and each may be spring biased against a separate portion of the pivot arm, as shown in fig. 18 of PCT international application PCT/US2018/000157, which is hereby incorporated by reference in its entirety.

Referring to fig. 12-15, control system 302 includes many of the corresponding features and operating principles of control system 102 described above, wherein like components are represented by like reference numerals. Thus, the following description will focus on the differences between control system 302 and control system 102.

The plate 365 of the control system 302 is configured to nest in a seat 382 defined by a groove 380 in the wall of the pivot axis adjustment sleeve 354. The seating of the plate 365 in the base 382 may provide improved mechanical alignment between the sensor and the sleeve 354.

A recess 363 in the end of the sleeve 354 may receive a tool for rotating the sleeve 354 within the receptacle. The position of the pivot axis 327 can be adjusted to properly center the pivot arm 122 between the pistons to ensure balanced loading between the two modules.

The sleeve 354 has an extension 396 to enhance contact between the inner wall of the sleeve 354 and the shaft 350. Unlike the shaft 150, the shaft 350 does not include a shoulder below the head, and correspondingly, unlike the sleeve 154, the sleeve 354 does not include a lip where the shaft shoulder would otherwise be. To limit vertical movement of the shaft 350 and feedback link, the top cap bolt 352 is elongated along the axis 327 as compared to the top cap bolt 152.

The configuration and arrangement of the shaft 350, sleeve 354, cap bolt 352, and plate 365 may provide enhanced alignment of these components relative to one another within the system 302.

Example embodiments

According to an exemplary embodiment of 1, there is provided a control system for controlling an angular position of a swash plate of an axial-piston hydraulic pump or motor, the angular position of the swash plate being determined by servo pistons, the control system comprising: valve means for supplying a charging pressure to the servo piston to cause the servo piston to change the angular position of the swash plate; a pivot arm configured to pivot about a pivot axis in coordination with movement of the servo piston, wherein an angular position of the pivot arm indicates an angular position of the swash plate, and wherein the pivot axis is adjustable at a position relative to the valve member and the servo piston; and a spring for transferring a spring load between the pivot arm and a valve member of the valve device.

According to an exemplary embodiment of 2, there is provided the exemplary embodiment of 1, further comprising a pivot shaft coupled to the pivot arm, the pivot shaft defining a pivot axis and being adapted to pivot about the pivot axis in cooperation with the pivot arm, the control system further comprising a pivot axis adjustment sleeve rotatably mounted therein, the pivot axis adjustment sleeve being mounted within a receptacle defined by a housing of the valve assembly, the pivot shaft being eccentric relative to the pivot axis adjustment sleeve such that rotation of the pivot axis adjustment sleeve relative to the housing of the valve assembly about its central axis adjusts the position of the pivot axis relative to the valve assembly and the servo piston.

According to example 3, there is provided example 2 wherein the pivot axis adjustment sleeve is configured to be locked at a set rotational position about its central axis relative to the housing of the valve assembly once the pivot axis is in a predetermined position.

According to a 4 th exemplary embodiment, there is provided a control system for controlling an angular position of a swash plate of an axial-piston hydraulic pump or motor, the angular position of the swash plate being determined by servo pistons, the control system comprising: valve means for supplying a charging pressure to the servo piston to cause the servo piston to change the angular position of the swash plate; a pivot arm configured to pivot about a pivot axis in coordination with movement of the servo piston, wherein an angular position of the pivot arm indicates an angular position of the swash plate; a spring for transferring a spring load between the pivot arm and a valve member of the valve device; and an angle sensor for sensing an angular position of the pivot arm, a housing of the angle sensor being angularly adjustable about the pivot axis relative to the pivot arm.

According to a 5 th exemplary embodiment, a 4 th exemplary embodiment is provided, wherein the plate is mounted to a housing of the angle sensor, and wherein the angle sensor is mounted on the plate.

According to an exemplary embodiment of 6, an exemplary embodiment of 5 is provided, wherein the angle sensor includes an angle sensing shaft extending through the plate and engaged with a pivot shaft coupled to the pivot arm such that the angle sensing shaft and the pivot shaft are configured to rotate together about the pivot axis.