POSITION SENSOR WITH MAGNET AND HALL EFFECT SENSOR FOR USER INPUT DEVICE ON A POWER MACHINE

Abstract: A user input device (102) receives a user input on a power machine (10). The user input device (102) includes a housing and a Hall Effect sensor (104) disposed on the housing. A magnetic element is movably disposed relative to the Hall Effect sensor (104). A handle, lever or foot pedal is operably coupled to the magnetic element such that operator actuation of the operator actuable input device causes movement of the magnetic element relative to the Hall Effect sensor (104). The Hall Effect sensor (104) provides an output signal indicative of such movement, and of the position of the magnet with respect to the Hall element.

Description: POSITION SENSOR ITH AGNET AND HALL EFFECT SENSOR FOR USER INPUT DEVICE ON A POWER MACHINE BACKGROUND OF THE INVENTION The present invention generally relates to 5 user input devices for power machines. In particular, the present invention relates to a sensor on a user input to a power machine . Power machines, such as skid steer loaders or mini-excavators, typically have a number of power 10 actuators. Such actuators can include, for example, drive actuators which provide traction power to the wheels or tracks of the machine. The actuators can also include those associated with manipulating a primary working tool, such as a bucket. In that case, 15 the actuators include lift and tilt actuators, and arm, boom, and swing or offset actuators. Of course, a wide variety of other actuators can also be used on such power machines . Examples of such actuators include auxiliary actuators, hand held or remote tool 20 actuators, or other actuators associated with the operation of the power machine itself, or a tool coupled to the power machine. The various actuators on such power machines have conventionally been controlled by mechanical 25 linkages. For example, when the actuators are hydraulic actuators controlled by hydraulic fluid under pressure, they have been controlled by user input devices such as handles, levers or foot pedals. The user input devices have been connected to a valve 30 spool, of a valve which controls flow of hydraulic fluid under pressure to the hydraulic actuator, by a mechanical linkage. The mechanical linkage transfers the user input motion into linear displacement of the valve spool to thereby control flow of hydraulic fluid 35 to the actuator. Electronic control inputs have also been developed. The electronic inputs include an electronic sensor which senses the position of user actuable input devices (such as hand grips and foot pedals) . In the past, such sensors have been resistive-type sensors, such as rotary or linear potentiometers . SUMMARY OF THE INVENTION A user input device receives a user input on a power machine. The user input device includes a housing and a Hall Effect sensor disposed on the housing. A magnetic element is movably disposed relative to the Hall Effect sensor. An operator actuable input is operably coupled to the magnetic element such that operator actuation of the operator actuable input causes movement of the magnetic element relative to the Hall Effect sensor. The Hall Effect sensor provides an output signal indicative of such movement. In one illustrative embodiment, the operator actuable input is a handle, or hand grip, which is movably connected to the housing. In another illustrative embodiment, the operator actuable input is a foot pedal movably coupled, by a pedal linkage, to the housing. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view of a power machine in accordance with one embodiment of the present invention. FIG. 2 is a block diagram of a control circuit in accordance with one embodiment of the present invention. FIG. 3 is an elevation view of one embodiment of a user input mechanism. FIG. 4 is a side sectional view of the user input mechanism taken along section lines 4-4 in FIG. 3. FIG. 5 is an exploded view illustrating the elements of the user input mechanism shown in FIGS. 3 and 4. FIG. 6 is an exploded view of another embodiment of a user input mechanism in accordance with one embodiment of the present invention. FIGS. 7A-7C show a perspective view, a side view and a cross-sectional view, respectively, of another embodiment of a user input mechanism in accordance with the present invention. FIG. 8 is an exploded view of a foot pedal linkage and lock in accordance with but one illustrative embodiment of the present invention. DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS The following detailed description should be read with reference to the drawings in which like elements in different drawings are numbered the same. The drawings, which are not necessarily to scale, depict selected embodiments and are not intended to limit the scope of the invention. FIG. 1 illustrates a perspective view of a skid steer loader 10 which can be used with the present invention. Skid steer loader 10 includes a mainframe assembly 16, a lift arm assembly 30, and an operator's compartment 40. An engine compartment 22 and a heat exchanger compartment 24 are illustratively located at the rear of the skid steer loader 10. Two pairs of wheels 12 are mounted to stub axles 14 and extend from both sides of the mainframe 16. Lift arm assembly 30 is mounted to upright members 20 of the mainframe assembly 16. Lift arm assembly 30 includes an upper portion formed by a pair of lift arms 32 which extend over wheels 12 and are pivotally mounted at a rear end to upright members 20. The front end of lift arms 32 are connected to a lower portion 33 which is pivotally attached to a tool (such as a bucket) 34. Lift arm assembly 30 is raised and lowered with respect to the mainframe assembly 16 by a pair of lift cylinders 36. Each of the lift cylinders 36 includes a first end pivotally mounted to upright member 20 and a second end pivotally mounted to lift arm 32. Bucket 34 is pivoted with respect to lift arm 32 by means of a bucket tilt cylinder (not shown) . In one illustrative embodiment, operator compartment 40 is partially enclosed by a cab 42 which includes side guard panels 44, overhead panel 46, rear guard panel 48, back panel 50 and seat pan 52. Cab 42 illustratively and optionally acts as an integral unit which is pivotally mounted at its rear to mainframe 16. With this arrangement, the entire cab, including seat 54 , may be pivoted upwardly and toward the rear of the loader 10 in order to permit access to the engine compartment 22 in addition to other mechanical and hydraulic systems of the skid steer loader 10. All functions of the skid steer loader 10 may be controlled by an operator who illustratively sits in the operator's compartment 40. The hydraulic drive system may be controlled using a pair of steering levers 58, one on each side of the seat. Each of the levers 58 can be moved independently in a forward and rearward direction. Movement of the levers 58 causes the wheels 12 on the corresponding side of the loader to rotate at a speed and in a direction corresponding to the extent and direction in which the respective lever 58 is moved. For example, if the left hand lever is moved in the forward direction, the left hand wheels 12 rotate in the forward direction at a speed corresponding to the distance the lever 58 has been moved. The lift cylinder 36 and the bucket tilt cylinder (not shown) are actuated by means of foot pedals (not shown) or operator inputs on handles or hand grips 39 on steering levers 58 or on a dash mounted toward the front of the operator's compartment 40. These and other aspects of the operation of the skid steer loader 10 are known to those skilled in the art. The user input mechanisms (such as handgrips 39 or foot pedals, now shown) can be used to provide user inputs to control one or more of the actuators illustrated in FIG. 1, or other actuators (such as actuators associated with different tools, hand held tools, auxiliary controlled tools, etc.) In other words, handgrips 39 are each illustratively pivotably coupled to a steering lever 58. The steering levers 58 are manipulated in a fore and aft direction, as described above. The handgrips 39 can be pivoted, for example, in a side-to-side orientation by the user. In accordance with one illustrative embodiment of the present invention, when one or the other of the handgrips 39 are pivoted, a Hall Effect sensor is arranged relative to the handgrip to sense pivoting movement of the handgrip. The Hall Effect sensor provides an electric signal which can be used to control the desired actuator. In one illustrative embodiment, the lift cylinders 36 or the tilt cylinder can be controlled by such a user input. Of course, substantially any other desired actuator can be controlled based on the user input as well. In a second embodiment, a foot pedal can be depressed by the user in order to control the desired actuator. In that embodiment, a Hall Effect sensor is arranged relative to the foot pedal to sense user depression of the foot pedal and provide an output signal indicative of that depression. The output signal from the Hall Effect sensor can then be used to control the desired actuator. This embodiment is illustrated in greater detail below with respect to FIG. 6. FIG. 2 is a block diagram of a control circuit 100 in accordance with one embodiment of the present invention. Control circuit 100 includes hand/foot input device 102, Hall Effect sensor 104, controller 106, valve actuator 108, valve 110 and actuator 112. In one illustrative embodiment, hand/foot input device 102 is a handle or handgrip which is moveable under the influence of operator actuation. In another illustrative embodiment, device 102 is a foot pedal which is depressible under the influence of operator actuation. In either case, Hall Effect sensor 104 is illustratively mounted closely proximate device 102 to sense movement of device 102 under the influence of operator actuation. Based on the sensed movement, Hall Effect sensor 104 provides an output signal to controller 106. In one illustrative embodiment, controller 106 is a digital computer, microcontroller, microprocessor or other similar control device which can have associated memory which is either integrated with the processor or microcontroller or provided separately therefrom. Controller 106 also illustratively includes suitable timing circuitry for providing appropriate timing signals. Based on the signal from Hall Effect sensor 104, controller 106 provides an output signal to valve actuator 108. Value actuator 108 is illustratively a ball screw motor, a stepper motor or another similar device which provides a mechanical output to valve 110 to move a valve spool within valve 110 to a desired position based upon the input signal from controller 106. Of course, valve actuator 108 can also be an electronic valve actuator, such as a coil or other electromagnetic or electronic device which is used to electromechanically or electromagnetically control the position of the valve spool within valve 110. In one illustrative embodiment, the output signal from controller 106 is a proportional signal which is proportional to the degree of movement of device 102, as actuated by the user. In other words, if the foot pedal is entirely depressed, the output from controller 106 causes valve actuator 108 to move the spool within valve 110 to one extreme position. Similarly, if the pedal is only half depressed, controller 106 controls valve actuator 108 to move the valve spool within valve 110 to an intermediate position. Valve 110 is illustratively a hydraulic valve which controls the flow of hydraulic fluid therethrough. Thus, when the valve spool within valve 110 is moved to an open position, hydraulic fluid under pressure is allowed to flow through valve 110 to actuator 112. Similarly, when the valve spool is in a closed position, hydraulic fluid under pressure is not allowed to flow through valve 110 to actuator 112. When the valve spool is controlled in a proportional manner, it can be moved to, for example, an infinite number of positions between the open position and closed position to allow metered flow of hydraulic fluid under pressure to actuator 112. Actuator 112 can be embodied as substantially any desired actuator. For example, actuator 112 can be the lift and tilt cylinders illustrated in FIG. 1, auxiliary actuators, electric, electronic or electromagnetic or electromechanical actuators, etc. Of course, it will be realized that when actuator 112 is not a hydraulic actuator, valve actuator 108 and valve 110 can be eliminated. It will also be appreciated that the signal from Hall Effect sensor 104 need not necessarily be provided to controller 106. Instead, with appropriate calibration circuitry, the signal provided by Hall Effect sensor 104 can be calibrated to directly control valve actuator 108. This is indicated by dashed arrow 114. FIG. 3 is a side elevational view of one embodiment of input device 102, in which device 102 is implemented as a handle or handgrip assembly. Device 102 includes housing 116 which includes a Hall Effect sensor housing portion 118, end cap 120, and protective boot or connection mechanism 120. Boot 120 connects the substantially rigid housing 116 to a reciprocal member, such as rod 122, which is disposed within an axial bore inside boot 120 and housing 116. The hand grip illustrated in FIG. 1 is illustratively 5 connected to member 122 such that, as the hand grip is pivoted, reciprocal member 122 is moved longitudinally within the bore in boot 120 and housing 116. In one illustrative embodiment, as is illustrated in greater detail below, reciprocal member 10 122 carries a magnetic element which moves proximate a Hall Effect sensor within housing portion 118. The Hall Effect sensor provides a signal indicative of the position of the magnetic element, within the longitudinal bore in housing 116, relative to the Hall 15 Effect sensor. FIG. 4 is a side sectional view taken along section lines 4-4 in FIG. 3. In addition, FIG. 5 is an exploded view of device 102 shown in FIGS. 3 and 4. Similar items are similarly numbered in FIGS. 3, 4 20 and 5. Housing 116 has a first portion 124 and a second portion 126. First portion 124 terminates at a first end 128 with an opening for receiving a portion of the assembly. End 128 also has a plurality of ears 25 130 which have threaded openings therein for threadably receiving screws 132. Screws 132 pass through apertures in end cap 120 to threadably secure end cap 120 and gasket 121 to housing 116. End cap 120 holds a pair of coupling members 30 134 and 136 within the first housing portion 124. Coupling member 136 has a shoulder 138 which abuts a similar shoulder 140 on coupling member 134. In this way, coupling member 136 is held within coupling member 134, such that it cannot pass all the way through the bore in coupling member 134. Coupling member 136 also includes a bore which is in communication with the bore in coupling member 134. Screw 142 is positioned within coupling member 136 and has its head resting against washer 123 and an annular shoulder 144 on coupling member 136. Screw 142 is also threadably secured within an end bore in reciprocal rod 122. Reciprocal rod 122 has a generally cylindrical magnetic element 146 disposed about its outer periphery. Magnetic element 146 is illustratively fixedly secured to the outer periphery of reciprocal rod 122 by an adhesive, welding or similar connection mechanism. Alternatively, magnetic element 146 can simply be biased into place through the use of springs or other similar bias elements. In the embodiment illustrated, housing 116 also contains cap 148 and compression spring 150. Compression spring 150 pushes at one end against an annular shoulder 152 of coupling member 134, and at its other end, against cap 148. This serves to hold magnetic element 146 in a generally neutral position with respect to the Hall Effect sensor which is contained within housing portion 118. In operation, the handgrip is coupled through coupling hole 154 of reciprocal element 122. Thus, when the operator pivots the handgrip in one direction, that causes reciprocal member 122 to move downwardly relative to housing 116. Thus, magnetic element 146 also moves downwardly relative to the Hall Effect sensor. This downward movement causes reciprocal rod 122 to push against cap 148 which, in turn, pushes against compression spring 150. This causes movement of magnetic element 146 downwardly with respect to the Hall Effect sensor. By contrast, when the operator pivots the handgrip in the opposite direction, this pulls on reciprocal rod 122 causing it to move reciprocally longitudinally upward relative to housing 118. Rod 122 acts to pull screw 142 and thus coupling members 134 and 136 upwardly, compressing spring 150 against cap 148. This causes movement upwardly, against the force of the compression spring, and hence causes controlled movement of magnetic element 146 upwardly relative to the Hall Effect sensor in housing portion 118. Magnetic element 146 is illustratively magnetized such that its first end 160 is magnetized according to a first polarity and its second end 162 is magnetized to the opposite polarity. This allows the Hall Effect sensor contained in housing 118 to provide a robust signal which indicates the relative position of magnetic element 146 relative to the Hall Effect sensor. FIG. 6 is an exploded view of device 102 implemented as a foot pedal position sensor. Similar items are similarly numbered to those shown in FIGS. 3-5. However, FIG. 6 illustrates that the upper end of housing 116 is not provided with a boot, but is instead provided with a fastening member 166. Fastening member 166 includes a pair of apertures 168 which are threaded to receive screws from a pedal linkage 170. FIG. 6 also shows that member 142 is fairly long and extends through the housing 116, while member 122 is somewhat shorter than that shown in FIGS. 3-5. Pedal linkage 170 is operably coupled to a pivotable pedal 172 to transfer pivotal movement of the pedal 172 to reciprocal movement of reciprocal rod 122 within housing 116. As with the embodiment illustrated in FIGS. 3-5, this causes reciprocal movement of magnetic element 146 relative to the Hall Effect sensor 104 contained within housing portion 118. Of course, pedal 172 can be biased in an upward or neutral position, as desired. FIGS. 7A-7C illustrate yet another embodiment of a user input mechanism in accordance with the present invention. FIGS. 7A-7C illustrate a perspective view, a side view, and a cross-sectional view of user input mechanism 200 implemented as a foot pedal position sensor in accordance with one illustrative embodiment of the present invention. It can be seen that a number of the items in device 200 are similar to those shown in the previous figures, and are similarly numbered. Specifically, the construction of device 200 is similar to that shown in FIGS. 3-5, in substantially all ways, except that fastening member, or flange, 166 is provided. Flange 166 is described in greater detail with respect to FIG. 6 above. Therefore, the user input mechanism can be manufactured and assembled in substantially identical fashion, regardless of whether it is a hand grip position sensor or a foot pedal position sensor, except for the small change in the housing of the device . FIG. 8 is an exploded view which illustrates the connection of device 200 to a portion of a foot pedal linkage and lock mechanism. FIG. 8 thus illustrates a number of components (collectively referred to as 202) which form a part of the foot pedal linkage. FIG. 8 also illustrates a number of parts (illustrated generally at 204) which form a portion of a locking mechanism. Flange 166 is fastened to block 206 which has a bore 207 therethrough from a bottom end 208 to a top end 210. Linkage shaft 212 enters shaft 207 from the top, while reciprocal member 122 enters shaft 207 from the bottom. Shaft 212 has an end 214 which is sized to receive, within it, the end of reciprocal member 122 such that aperture 154 is aligned with a pair of apertures 216 on shaft 212. Pin 218 is inserted through the aligned apertures to connect member 122 to shaft 212. Boot 220 has an internal bore which is sized to fit over an upper portion of shaft 212 and be secured thereabout by securing flange 222 and a pair of screws 224 which pass through apertures in flange 222 and are threadably secured into apertures 226 of block 206. The upper end 228 of shaft 212 has an opening, or slot 230 and generally aligned apertures 232. Slot 230 is sized to receive an end of a bar, or other pedal linkage 234. An aperture 236 in bar 234 is aligned with apertures 232 in the upper end 228 of shaft 212. A fastening bolt 238 is passed through aligned apertures 232 and 236 and secured therein with nut 240. This allows bar 234 to pivot about bolt 238, or at least move reciprocally up and down on the page of FIG. 8 to move shaft 212 in a corresponding, reciprocal fashion within bore 207 in block 206. Since shaft 212 is connected to reciprocal member 122, reciprocation of shaft 212 also causes reciprocation of member 122 within mechanism 200. It will be appreciated that bar 234 is then further coupled to additional mechanical pedal linkages which extend, for example, under a seat pan in the power machine (e.g., skid steer loader) in which the foot pedal is located. Thus, pressing of the foot pedal causes corresponding movement of bar 234 and reciprocation of member 122 within mechanism 200. FIG. 8 also shows that block 206 illustratively includes a second bore 240 therethrough. Bore 240 communicates with bore 207 and extends from a side of bore 207. An electrically actuated solenoid 242 has an end 244 which is illustratively threadably secured within bore 240. Solenoid 242 also includes a plurality of conductors 246 which extend back to an electronic controller, such as controller 106. Solenoid 242 is movable between an extended position, in which the solenoid extends outwardly toward the interior of block 206, and a retracted position wherein the solenoid is retracted back away from bore 207 in block 206. Shaft 212 is sized such that it can be reciprocated so that a groove 248, or other type of notch, is movable adjacent solenoid 242. Therefore, when solenoid 242 moves to its extended position, it engages notch 248 and thereby locks reciprocal movement of shaft 212 relative to block 206. This allows selective locking of the user input mechanism, in case the hand input mechanism is selected over the foot pedal mechanism. A similar lock can, of course, be provided on the hand grip mechanism as well. Thus, it can be seen that the present invention includes a Hall Effect sensor for sensing movement of a user input mechanism which is actuable by a user to control substantially any desired actuator. This provides a robust mechanism for control in many harsh environments which can be encountered by power machines, such as skid steer loaders, mini • excavators, etc. Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.

Claims: WHAT IS CLAIMED IS: 1. A user input device receiving a user input on a power machine, the user input device comprising: a housing; a Hall Effect sensor disposed on the housing; a magnetic element movably disposed relative to the Hall Effect sensor; and an operator actuable input, operably coupled to the magnetic element such that operator actuation of the of the operator actuable input causes movement of the magnetic element relative to the Hall Effect sensor, the Hall Effect sensor providing an output signal indicative of such movement. 2. The user input device of claim 1 wherein the housing defines an opening therein and further comprising : a reciprocal element reciprocally mounted in the opening and coupled to the operator actuable input and the magnetic element such that movement of the operator actuable input drives reciprocation of the reciprocal element and the magnetic element relative to the housing. 3. The user input device of claim 2 wherein the magnetic element comprises: a generally cylindrical element defining a generally longitudinal bore therethrough, the generally longitudinal bore receiving, and being connected to, the reciprocal element. 4. The user input device of claim 3 wherein the operator actuable input further comprises: a boot substantially enclosing a connection between the reciprocal element and the housing. 5. The user input device of claim 3 wherein the operator actuable input comprises: a handle coupled to the reciprocal element such that movement of the handle drives reciprocation of the reciprocal element . 6. The user input device of claim 5 wherein the handle comprises a hand grip. 7. The user input device of claim 3 wherein the operator actuable input comprises : a foot pedal coupled to the reciprocal element such that movement of the foot pedal drives reciprocation of the reciprocal element . 8. The user input device of claim 2 and further comprising: a bias member biasing the reciprocal element to a predetermined position relative to the Hall Effect sensor. 9. A user input mechanism receiving a user input on a skid steer loader and providing an output signal indicative of the user input, comprising: a housing having a bore therethrough; a movable element axially movable in the bore ; a magnetic element disposed on the housing or movable with the movable element; a Hall Effect sensor disposed on the housing or movable with the movable element such that movement of the movable element causes relative movement between the magnetic element and the Hall Effect sensor; and a user actuable element operably coupled to the movable element such that user manipulation of the user actuable element causes axial movement of the movable element relative to the housing . 10. The user input mechanism of claim 9 wherein the user actuable element comprises: a foot pedal coupled to the movable element such that movement of the foot pedal drives reciprocation of the movable element . 11. A skid steer loader, comprising: a hydraulic power system providing hydraulic fluid under pressure; a power actuator coupled to the hydraulic power system to receive the hydraulic fluid under pressure; and a user input device, comprising: a housing; a Hall Effect sensor disposed on the housing; a magnetic element movably disposed relative to the Hall Effect sensor; and an operator actuable input, operably coupled to the magnetic element such that operator actuation of the of the operator actuable input causes movement of the magnetic element relative to the Hall Effect sensor, the Hall Effect sensor providing an output signal indicative of such movement.

Inventors: HANSEN RON, JACOBSON SCOTT B, HANSEN, RON, JACOBSON, SCOTT, B.
Applicants: CLARK EQUIPMENT CO, CLARK EQUIPMENT COMPANY
Application year: 2000
Main classification: G01D5
IPC codes: E02F9, G01B7, G01D5, G01D11, G05G25