WO2023019133A1

WO2023019133A1 - Dynamometers and methods of measuring torque

Info

Publication number: WO2023019133A1
Application number: PCT/US2022/074703
Authority: WO
Inventors: Kevin DISCHINO; Narayanan Ramakrishnan
Original assignee: Siemens Healthcare Diagnostics Inc.
Priority date: 2021-08-12
Filing date: 2022-08-09
Publication date: 2023-02-16

Abstract

A dynamometer includes a torque measuring device configured to measure torque applied to the torque measuring device; a clutch having a clutch input and a clutch output, the clutch output coupled to the torque measuring device and the clutch input configured to be coupled to a motor under test; wherein friction between the clutch input and the clutch output is variable; and a dampening mechanism configured to dampen the friction between the clutch input and the clutch output. Other dynamometers and methods of measuring torque are disclosed.

Description

DYNAMOMETERS AND METHODS OF MEASURING TORQUE

CROSS REFERENCE TO RELATED APPLICATION

[001] This application claims the benefit of U.S. Provisional Patent Application No. 63/232, 627, entitled "DYNAMOMETERS AND METHODS OF MEASURING TORQUE" filed August 12, 2021, the disclosure of which is hereby incorporated by reference in its entirety for all purposes.

FIELD

[002] Embodiments of this disclosure relate to dynamometers and methods of measuring torque and speeds of motors.

BACKGROUND

[003] Dynamometers measure torque generated by spinning or rotating devices, such as motors. Some specifications of motors include torque as a function of motor speed (e.g. , RPMs) . When torques of relatively small motors are measured as a function of motor speed, the measurements may be inaccurate due to certain forces in the dynamometers. Therefore, dynamometers that provide accurate torque measurements and torque measurements as a function of motor speed are sought.

SUMMARY

[004] According to a first aspect, a dynamometer is provided. The dynamometer includes a torque measuring device configured to measure torque applied to the torque measuring device; a clutch having a clutch input and a clutch output, the clutch output coupled to the torque measuring device and the clutch input configured to be coupled to a motor under test, wherein friction between the clutch input and the clutch output is variable; and a dampening mechanism configured to dampen the friction between the clutch input and the clutch output.

[005] According to a second aspect, a dynamometer is provided. The dynamometer includes a torque measuring device configured to measure torque applied to the torque measuring device; a clutch having a clutch input and a clutch output, the clutch output coupled to the torque measuring device and the clutch input configured to be coupled to a motor under test; wherein friction between the clutch input and the clutch output is dependent on force applied between the clutch input and the clutch output; an actuator configured to apply force between the clutch input and the clutch output; a spring mechanism located between the actuator and the torque measuring device, the spring mechanism configured to dampen the force applied on the clutch by the actuator; and a tachometer configured to measure speed of the motor under test .

[006] According to a method aspect, a method of operating a dynamometer is provided. The method includes operating a motor under test; coupling the motor under test to a torque measuring device using a clutch; and engaging the clutch by applying a force to the clutch, wherein the force applied to the clutch is dampened by a dampening device.

[007] Still other aspects, features, and advantages of this disclosure may be readily apparent from the following description and illustration of a number of example embodiments, including the best mode contemplated for carrying out the disclosure. This disclosure may also be capable of other and different embodiments, and its several details may be modified in various respects, all without departing from the scope of the disclosure. This disclosure is intended to cover all modifications, equivalents, and alternatives falling within the scope of the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[008] The drawings, described below, are for illustrative purposes, and are not necessarily drawn to scale. Accordingly, the drawings and descriptions are to be regarded as illustrative in nature, and not as restrictive. The drawings are not intended to limit the scope of the disclosure in any way .

[009] FIG. 1A illustrates a side elevation view of a dynamometer measuring torque and speed of a motor under test according to one or more embodiments.

[0010] FIG. IB illustrates an enlarged view of the spring mechanism of FIG. 1A according to one or more embodiments.

[0011] FIG. 2 is a graph illustrating example plots of torque as a function of motor speed as measured by the dynamometer of FIG. 1A according to one or more embodiments.

[0012] FIG. 3A illustrates a side elevation view of another dynamometer measuring torque and speed of a motor under test according to one or more embodiments.

[0013] FIG. 3B illustrates a top plan view of the dynamometer of FIG. 3A according to one or more embodiments.

[0014] FIG. 4 illustrates a side elevation view of another dynamometer measuring torque and speed of a motor under test according to one or more embodiments.

[0015] FIG. 5 illustrates a top plan view of a dynamometer that provides a radial dampened load during torque and speed measurements according to one or more embodiments.

[0016] FIG. 6 illustrates a side elevation view of a dynamometer including a linear actuator assembly configured to move a motor under test according to one or more embodiments.

[0017] FIG. 7 illustrates a flowchart of a method of operating a dynamometer according to one or more embodiments .

DETAILED DESCRIPTION

[0018] Motors may be rated based on torque output as a function of motor speed. Measuring torque as a function of motor speed is especially difficult for micro and/or miniature motors. For example, small disruptions in forces applied to the spinning motors during torque measurements may cause inaccurate torque measurements. Some conventional dynamometers apply loads as step functions, which may not provide accurate torque measurements.

[0019] Dynamometers and methods of measuring torque as a function of motor speed disclosed herein apply gradual or dampened loads to motors to provide more accurate torque measurements. The dynamometers include a dampening mechanism that applies dampened loads to the motors under test. Thus, torque as a function of motor speed is accurately measured. These and other dynamometers and methods of measuring torque as a function of motor speed are described in greater detail with reference to FIGS. 1A-7.

[0020] Reference is made to FIG. 1A, which is a side elevation view of a dynamometer 100 measuring torque of a motor under test, which is referred to herein as the motor 102. The dynamometer 100 may include a frame 106 on which components of the dynamometer 100 described herein are affixed. The dynamometer 100 includes a torque measuring device, which in the embodiment of FIG. 1A is a strain gauge 108. Other torque measuring devices may be used in different dynamometer embodiments. The strain gauge 108 includes a strain gauge input 108A that may be coupled to a clutch 110. The strain gauge 108 may include circuitry or the like (not shown) configured to generate electronic signals indicative of torque (e.g. , strain) applied to the strain gauge input 108A. The electronic signals may be processed by a computer 112 as described herein. As described herein, the clutch 110 couples the motor 102 to the strain gauge 108. The clutch 110 includes a clutch input 110A coupled to a motor output 102A and a clutch output HOB coupled to the strain gauge input 108A. Other devices may be located between the motor 102 and the strain gauge 108. [0021] The clutch 110 may have variable friction between the clutch input 110A and the clutch output HOB. Thus, the motor output 102A may spin freely when the clutch 110 is in a state where no friction is applied between the clutch input 110A and the clutch output HOB. As the friction between the clutch input 110A and the clutch output HOB is increased, torque generated by the motor 102 is applied to the strain gauge 108. The strain gauge 108 generates the above-described signals indicative of the torque generated by the motor 102.

[0022] The dynamometer 100 may include a tachometer 116 configured to generate signals indicative of the speed (e.g. , RPMs) of the motor 102. In the embodiment of FIG. 1A, the tachometer 116 may include a hall effect sensor 116A located adjacent the motor output 102A. The tachometer 116 may be located in other positions in the dynamometer 100. A magnet 116B may be coupled to the motor output 102A so as to spin with the motor output 102A. Rotation of the magnet 116B may be detected by the hall effect sensor 116A. The magnet 116B may be coupled to other components that spin at the same speed as the motor 102. In other embodiments, other types of tachometers may be used. For example, the tachometer 116 may be an optical tachometer. The output of the tachometer 116, such as an output of the hall effect sensor 116A, may be input to the computer 112. In some embodiments, the computer 112 may calculate the speed of the motor 102 based on the output of the tachometer 116.

[0023] As described above, the computer 112 may receive data generated by the strain gauge 108 and the tachometer 116. The computer 112 may include a processor 112A and memory 112B, wherein the processor 112A is configured to execute programs 112C stored in the memory 112B. In some embodiments, the programs 112C may calculate torque and speed of the motor 102. In some embodiments, the computer 112 may generate signals to cause a display 114 to display the torque and speed information. The display 114 may be configured to display other information.

[0024] In some embodiments, a slide 120 may be attached to the frame 106. In some embodiments, the slide 120 may be integral with the frame 106. The slide 120 may enable one or more of the components of the dynamometer 100 to slide relative to the strain gauge 108 and/or other components of the dynamometer 100. For example, the slide 120 may enable one or more components to move in an x direction, which includes a -x direction and a +x direction. In the embodiment of FIG. 1A, the dynamometer 100 may include one or more carriages that are slidable in the x-direction. In the embodiment of FIG. 1A, the dynamometer 100 may include a first carriage 122 that is configured to support the motor 102 and enable the motor 102 to move in the x-direction relative to the clutch 110. The first carriage 122 may include a first side 122A onto which the motor 102 may be affixed.

[0025] The first carriage 122 also may include a second side 122B wherein at least one dampening mechanism may be configured to contact and/or be attached to the second side 122B. In some embodiments, the dampening mechanism may be or include a force transmission device configured to transfer force between the motor 102 and the strain gauge 108. In the embodiment of FIG. 1A, the dampening mechanism is one or more spring mechanisms 126 that are configured to contact and/or be attached to the second side 122B. In the embodiment of FIG. 1A, the dynamometer 100 may include a first spring mechanism 126A and a second spring mechanism 126B attached and/or configured to contact the second side 122B. In some embodiments, the dynamometer 100 may include a single spring mechanism or more than two spring mechanisms. Other dampening mechanisms and/or force transmission devices may include shock absorbers, hydraulic devices, or any device that dampens and/or reduces a load or force applied to the strain gauge 108. In some embodiments, the dampening mechanism may reduce the force applied to the clutch 110 per unit displacement of an actuator (e.g. , bolt 134) coupled to the clutch 110.

[0026] In some embodiments, the dynamometer 100 may include a second carriage 128 that may be slidable in the x-direction. The second carriage 128 may include a first side 128A located opposite a second side 128B. The first side 128A may be configured to attach and/or contact the dampening mechanism, which in the embodiment of FIG. 1A is the spring mechanisms 126. The first side 128A of the second carriage 128 may be substantially parallel to the second side 128B. The parallel surfaces may provide uniform force applied to the first carriage 122 by compression of the spring mechanisms 126.

[0027] Additional reference is made to FIG. IB, which illustrates an enlarged view of the first spring mechanism 126A, which may be representative of all the spring mechanisms 126. The first spring mechanism 126A may include a pin 124 surrounded by a coil spring 125. The coil spring 125 may be movable relative to the pin 124. The first spring mechanism 126A may include a spring first end 127A and a spring second end 127B. The spring first end 127A may be configured to contact the second side 122B of the first carriage 122 and the spring second end 127B may be configured to contact the first side 128A of the second carriage 128. The spring constant of the coil spring 125 and the spring constants of other ones of the spring mechanisms 126 may be selected based on the force applied to the clutch 110 and dampening needed between the first carriage 122 and the second carriage 128.

[0028] In some embodiments, the pin 124 may be received in an opening 129 in the first side 128A of the second carriage 128, which enables the pin 124 to move relative to the second carriage 128. Thus, the pin 124 enables the first carriage 122 and the second carriage 128 to move relative to one another while maintaining the first spring mechanism 126A between the first carriage 122 and the second carriage 128.

[0029] In some embodiments, the dynamometer 100 may include a block 130 or fixed component that is affixed to the frame 106. The block 130 may include a threaded bore 132 through which a bolt 134 may be threaded. The bolt 134 may be configured to contact the second side 128B of the second carriage 128. When the bolt 134 turns in the bore 132, the bolt 134 applies a force to the second carriage 128. In the embodiments, the bolt 134 may include a knob 134A to enable a user to rotate the bolt 134. In some embodiments, devices that apply a force to the second carriage 128 other than the bolt 134 may be used.

[0030] During operation of the dynamometer 100, the bolt 134 may be rotated to move the bolt 134 in the +x direction so that the spring mechanisms 126 apply minimal or no force to the first carriage 122. The lack of force applied by the spring mechanisms 126 to the first carriage 122 in the +x direction reduces force in the clutch 110. In some embodiments, the bolt 134 is moved in the +x direction to a point where there is no friction applied in the clutch 110 between the clutch input 110A and the clutch output HOB. Thus, in this configuration, the motor 102 does not apply torque to the strain gauge 108.

[0031] Power may then be applied to the motor 102, which causes the motor output 102A to spin. In some embodiments, the motor 102 may not be physically coupled to the strain gauge 108 during this stage of operation of the dynamometer 100. For example, because there is minimal or no friction in the clutch 110, the motor 102 may be able to spin freely. In some embodiments, current supplied to the motor may be set to predetermined amperages as described herein. As the motor output 102A is spinning, the tachometer 116 may measure the speed of the motor output 102A. In some embodiments, the speed of the motor output 102A is measured in revolutions per minute (RPMs) .

[0032] The motor output 102A of the spinning motor 102 may be gradually, physically coupled to the strain gauge 108 via the clutch 110. During the gradual physical coupling, the speed of the motor output 102A and torque measured by the strain gauge 108 may be recorded, such as by one or more of the programs 112C executing by the processor 112A. The physical coupling may be achieved by turning the bolt 134 so that the bolt 134 moves in the -x direction. As the bolt 134 moves in the -x direction, the movement of the bolt 134 slides the second carriage 128 in the -x direction.

[0033] As the second carriage 128 slides in the -x direction, the movement (e.g. , sliding) applies a spring force in the -x direction to the first carriage 122. The spring force causes the first carriage 122 to move in the -x direction and/or apply a force to the clutch input 110A in the -x direction.

The spring mechanisms 126 dampen the force applied by the bolt 134 moving in the -x direction on the first carriage 122. For example, as the first spring mechanism 126A compresses, the pin 124 may move further into the opening 129. The compression of the spring mechanisms 126 reduces the force applied per unit displacement of the bolt 134, and dampens the movement of the first carriage 122, which dampens the force applied to the clutch 110. The result is that the frictional force applied between the clutch input 110A and the clutch output HOB is also dampened. For example, as the bolt 134 is moved in the -x direction, the frictional force between the clutch input 110A and the clutch output HOB may be a gradual ramp function or another function rather than a function having a sharp transition, such as a step function. The dampened frictional force applied between the clutch input 110A and the clutch output HOB provides more accurate torque measurements, especially when the motor 102 is a low torque motor.

[0034] As the friction between the clutch input 110A and the clutch output HOB increases, the torque applied to the strain gauge 108 increases, which causes the motor speed to decrease. The decreased speed of the motor 102 may be measured by the tachometer 116. Eventually, the friction in the clutch 110 may increase to a point where the strain gauge 108 prevents the motor 102 from spinning. The programs 112C may generate data showing relations between the speed of the motor 102 measured by the tachometer 116 and the torque of the motor 102 measured by the strain gauge 108.

[0035] Additional reference is made to FIG. 2, which is a graph 200 illustrating example plots of torque as a function of motor speed as measured by the dynamometer 100. The different plots in the graph 200 are generated with different operating currents supplied to the motor 102. The torque measurements may be more accurate than torque measured by conventional dynamometers because the dampening mechanisms (e.g. , the spring mechanisms 126) gradually apply force between the clutch input 110A and the clutch output HOB. The gradually applied force may be dampened force, which provides more accurate measurements of the actual torque generated by the motor 102.

[0036] Additional reference is made to FIGS. 3A-3B, which illustrate another embodiment of a dynamometer 300, which may function in a matter similar to the dynamometer 100 of FIG. 1A. FIG. 3A illustrates a side elevation view of the dynamometer 300 and FIG. 3B illustrates a top plan view of the dynamometer 300. In the embodiment of FIGS. 3A-3B, the dynamometer 300 may include a slide 320 that may be identical or substantially similar to the slide 120 (FIG. 1A) . The slide 320 may include a first rail 320A and a second rail 320B on which components of the dynamometer 300 may slide in the x- direction. The dynamometer 300 may include other embodiments of the slide 320, including linear bearings, magnetic slides, monorails, and recessed tracks. In some embodiments, the slide 320 may be integral with the frame 106.

[0037] In the embodiment of FIGS. 3A-3B, the dynamometer 300 may include a first carriage 322 and a second carriage 328 slidable on the slide 320. The first carriage 322 and the second carriage 328 may be movable in the x-direction (e.g. , - x direction and +x direction) by sliding on the slide 320. In some embodiments, the first carriage 322 and/or the second carriage 328 may have wheels (not shown) that contact the first rail 320A and the second rail 320B and enable the first carriage 322 and/or the second carriage 328 to slide or move on the slide 320.

[0038] In the embodiment of FIGS. 3A-3B, a first bracket 324 may be coupled to the first carriage 322 and a second bracket 329 may be coupled to the second carriage 328. The first bracket 324 may be configured to support the motor 102 and/or other components in a manner similar to the first carriage 122 (FIG. 1A) . However, the first bracket 324 may be configured to be attachable and detachable from the first carriage 322.

Thus, different configurations of the first bracket 324 may be readily attached to the first carriage 322. The different configurations of the first bracket 324 enable different configurations of the motor 102 to be tested in the dynamometer 300 by simply changing the first bracket 324 to accommodate different ones of the motor 102. Different configurations of the first bracket 324 may also accommodate different configurations and numbers of the spring mechanisms 126 in the dynamometer 300. [0039] The dynamometer 300 may include a tachometer 316. In the embodiment of FIGS. 3A-3B, the tachometer 316 may be affixed to the first bracket 324. Accordingly, the tachometer 316 may be moveable with the motor 102. This configuration enables the tachometer 316 to provide accurate measurements of the speed of the motor 102 irrespective of the position of the motor 102 on the slide 320.

[0040] The second bracket 329 may be configured to apply the force applied by the bolt 134 to the spring mechanisms 326. The second bracket 329 may also be configured for other purposes. The second bracket 329 may be configured to be attachable and removable from the second carriage 328. Thus, different configurations of the second bracket 329 may be readily attached to the second carriage 328. The different configurations of the second bracket 329 enable different configurations of the spring mechanisms 326 and bolt 134 to be used in the dynamometer 300. Different configurations of the second bracket 329 may also accommodate other components.

[0041] Du ring use of the dynamometer 300, a user may select a motor that is to be tested, which in the embodiment of FIGS. 3A-3B may be the motor 102. The user may then select a first bracket 324 that is configured to receive and/or support the motor 102. For example, the first bracket 324 may be selected to match the physical characteristics, such as the mounting configuration, of the motor 102. In some embodiments, the first bracket 324 may be selected at least partially based on the number, types, and/or spring constants of the spring mechanisms 326. A selected first bracket 324 may then be attached to the first carriage 322.

[0042] The user may also select an appropriate second bracket and may attach the selected second bracket to the second carriage 328. The second bracket 329 may be selected based on the number, types, and/or spring constants of the spring mechanisms 326. The second bracket 329 may also be selected based on the type of the bolt 134 that may contact the second bracket 329.

[0043] When the first bracket 324 and the second bracket 329 are attached to the first carriage 322 and the second carriage 328, respectfully, the bolt 134 may be moved so that the bolt 134 applies minimal or no force to the second bracket 329. Therefore, there is no or minimal frictional force in the clutch 310, so the motor 102 is not coupled to the strain gauge 108. The computer 112 (FIG. 1A) and/or the programs 112C may then generate instructions that cause the motor 102 to spin. As the motor 102 spins, the tachometer 316 measures the speed of the motor 102. Data generated by the tachometer 316 may be received by the computer 112 and/or the programs 112C and processed, such as shown in FIG. 2.

[0044] The bolt 134 may be rotated to apply a force in the -x direction on the second bracket 329. In some embodiments, a user may turn the knob 134A so that the bolt 134 applies the force to the second bracket 329. The force applied to the second bracket 329 applies a force to the first bracket 324 in the -x direction by way of the spring mechanisms 126. The spring mechanisms 326 dampen the force applied to the first bracket 324. Should the bolt 134 jerk or experience step functions or the like during turning, the dampening provided by the spring mechanisms 326 may attenuate or dampen the jerkiness and/or step functions. Therefore, the movement of the first bracket 324 may be smoother than the movement of the second bracket 329. The spring mechanism 126 also reduces the force applied per unit displacement of the bolt 134. Therefore, force is applied more gradually to the clutch 310. The spring mechanism 126 may also provide a linear dependence or mostly linear dependence of the force applied by the displacement of the bolt 134, hence making the application of force smoothly controllable . The linear dependence may be applied to both manual as well as mechanized/automated application of the force.

[0045] As the first bracket 324 moves in the -x direction, the first bracket 324 applies the dampened force to the clutch 310, which causes a frictional force within the clutch 310. The frictional force within the clutch 310 causes the torque generated by the motor 102 to be applied to the strain gauge 108. The strain gauge 108 measures the torque and may generate data indicative of the measured torque. The data may be received by the computer 112 (FIG. 1A) and/or one or more of the programs 112C. As the bolt 134 is moved in the -x direction, the dampened force applied to the clutch 310 increases, so more torque generated by the motor 102 is applied to the strain gauge 108. Eventually, the torque generated by the motor 102 cannot overcome forces in the strain gauge 108, which causes the motor 102 to stall.

[0046] The computer 112 and/or the programs 112C may process data generated by the strain gauge 108 and the tachometer 316. In some embodiments, the programs 112C may generate data showing torque generated by the motor 102 as a function of speed of the motor 102 as shown in FIG. 2. The computer 112 and/or the programs 112C may output the data to the display 114. In some embodiments, as shown in FIG. 2, the torque of the motor 102 as a function of motor speed may be measured during different operating conditions, such as different drive currents applied to the motor 102.

[0047] Reference is now made to FIG. 4, which illustrates another embodiment of a dynamometer 400 used to test the motor 102. The dynamometer 400 may include a frame 406 that supports components of the dynamometer 400. A rotary torque transducer 408 may be attached to the frame 406. The rotary torque transducer 408 includes an input 408A and an output 408B that may be resiliently coupled together. The strain between the input 408A and the output 408B may be measured as both the input 408A and the output 408B rotate. For example, a spring (not shown) may couple the input 408A to the output 408B. When a force is applied to the input 408A, the spring will deflect causing a deflection angle between the input 408A and the output 408B. The deflection angle is proportional to the torque applied at the input 408A relative to a load on the output 408B. Data representative of the deflection angle may be output to the computer 112 where the programs 112C may generate plots of torque as a function of motor speed as shown in FIG. 2, for example.

[0048] In the embodiment of FIG. 4, the dynamometer 400 may include a bracket 422 that supports the motor under test (the motor 102) . In some embodiments, the bracket 422 may be rigidly affixed to the frame 406. For example, the bracket 422 may be maintained in a fixed position relative to the rotary torque transducer 408. The programs 112C may generate signals that cause power to be supplied to the motor 102 and cause the motor output 102A to spin.

[0049] The dynamometer 400 may include a tachometer 416 configured to generate data indicative of the speed of the motor 102. The data may be processed by one or more of the programs 112C to generate torque versus speed data as shown in FIG. 2, for example. In some embodiments, the tachometer 416 may be identical or substantially similar to the tachometer 316 (FIG. 3A) and/or the tachometer 116 (FIG. 1A) . In some embodiments, the tachometer 416 may be integrated into the rotary torque transducer 408. In such embodiments, the data generated by the rotary torque transducer 408 may include data indicative of the speed of the input 408A.

[0050] In the embodiment of FIG. 4, a dampened load may be applied to the output 408B of the rotary torque transducer 408. The dampened load may be applied axially (e.g. , in the x- direction) to the output 408B of the rotary torque transducer 408. In the embodiment of FIG. 4, the dampened load may be applied by a clutch 410 mounted to a first side 436A of a first carriage 436, wherein the first carriage 436 is movable (e.g. , slidable) in the x-direction relative to the rotary torque transducer 408. The clutch 410 may be identical or substantially similar to the clutch 110 (FIG. 1) . The amount of frictional force exerted by the clutch 410 may be proportional to the axial force in the x-direction exerted between the clutch 410 and the rotary torque transducer 408. For example, the friction applied by the clutch 410 may increase as the clutch 410 is forced in the +x direction toward the output 408B of the rotary torque transducer 408. Likewise, the friction applied by the clutch 410 may be reduced as the clutch 410 is moved away (in the -x direction) from the rotary torque transducer 408. The friction applied by the clutch 410 applies a dampened load on the motor 102 as described herein.

[0051] In some embodiments, the first carriage 436 may be coupled to the frame 406 via a slide 420 that may be substantially similar to or identical to the slide 120 (FIG. 1A) and/or the slide 320 (FIG. 3A) . The slide 420 enables the first carriage 436 to move (e.g. , slide) in the x-direction relative to the frame 406. Other mechanisms may be used to enable the first carriage 436 to move relative to the frame 406.

[0052] In some embodiments, the dynamometer 400 may include a second carriage 438 movable relative to the frame 406. In some embodiments, the second carriage 438 may be coupled to the slide 420 and may be movable (e.g. , slidable) on the slide 420. The second carriage 438 may include a first side 438A that faces the second side 436B of the first carriage 436. A dampening mechanism, such as spring mechanisms 426 may be located between the first side 438A and the second side 436B. The spring mechanisms 426 may function as a dampening mechanism and may include one or more spring mechanisms as shown in FIG. 4. The one or more spring mechanisms may be identical or substantially similar to the first spring mechanism 126A illustrated in FIG. IB. Other dampening mechanisms may be used in the dynamometer 400.

[0053] In some embodiments, a bracket 432 may be secured to the frame 406. The bracket 432 may include a threaded bore 433 in which a bolt 434 is configured to be threaded into. The bolt 434 may be configured to contact a second side 438B of the second carriage 438. As the bolt 434 is rotated in the bore 433, the bolt moves in the x-direction. Thus, the bolt 434 may be rotated in the bore 433 to move the bolt 434 in the +x direction and apply a force to the second carriage 438 and ultimately apply a dampened force to the clutch 410. In some embodiments, an actuator (not shown in FIG. 4) may cause the bolt 434 to turn relative to the bore 433. In some embodiments, the actuator may be controlled by the computer 112 and/or one or more of the programs 112C.

[0054] During operation of the dynamometer 400, the bolt 434 may be rotated to relieve force applied on the clutch 410, which enables the motor 102 to spin with only an incidental load produced by the rotary torque transducer 408. The computer 112 and/or programs 112C may record the speed of the motor 102 via the tachometer 416 and torque generated by the motor 102 via the rotary torque transducer 408. The bolt 434 may then be rotated to move in the +x direction, which causes the second carriage 438 to slide in the +x direction. The initial movement and other movement of the bolt 434 in the +x direction may cause sudden transitions, such as step functions to be applied to the second carriage 438. If these sudden transitions are applied to the clutch 410 , the torque mea surements generated by the rotary torque transducer 408 may be inaccurate . The dynamometer 400 uses the spring mechanisms 426 to dampen the force applied on the clutch 410 by the bolt 434 . For example , movement of the second carriage 438 compres ses the spring mechanisms 42 6 as the spring mechanisms 426 apply a force on the first carriage 436 causing the first carriage 436 to move in the +x direction . Thus , the force applied by the first carriage 436 in the +x direction is dampened relative to the force applied to the second carriage 438 .

[ 0055] The movement of the first carriage 436 in the +x direction applies a dampened force to the clutch 410 . As the force is applied to the clutch 410 , friction in the clutch 410 increase s and applies a load to the motor 102 via the rotary torque transducer 408 . The rotary torque transducer 408 mea sures the torque generated by the load and generate s data indicative of the torque . One or more of the programs 112C may then generate data showing the torque as a function of speed ( e . g . , RPMs ) of the motor 102 . One or more of the programs 1120 may generate other data that may include torque and/or speed of the motor 102 . The dampening provided by the spring mechanism 42 6 provide s more accurate torque measurements and allows force to be applied more gradually to the clutch 410 per unit displacement of the bolt 134 .

[ 0056] Reference is now made to FIG . 5 , which illustrates a block diagram of a dynamometer 500 including a frame 506 . The dynamometer 500 provides a radial dampened force during torque mea surements rather than an axial dampened force . The radial dampened force may be perpendicular to the rotational axis of the motor 102 . The dynamometer 500 may be substantially similar to the dynamometer 400 except that the dynamometer 500 applies the dampened load radially instead of axially . Thus , the dampened load is applied in the -y direction, which is perpendicular to the x-direction. The clutch 510 in the dynamometer 500 may be similar to a brake that applies the dampened force radially to the output 408B of the rotary torque transducer 408. For example, the clutch 510 may be a friction pad that applies a force in the -y direction to load the motor 102.

[0057] During operation, the bolt 434 may be rotated so that the bolt 434 moves in the +y direction, which reduces or eliminates friction between the clutch 510 and the output 408B of the rotary torque transducer 408. The bolt 434 may then be rotated to move in the -y direction, which causes the second carriage 438 to slide in the -y direction. The movement of the bolt 434 in the -y direction may cause sudden transitions, such as step functions to be applied to the second carriage 438. If these sudden transitions are applied to the clutch 510, the torque measurements of the rotary torque transducer 408 may be inaccurate. The dynamometer 500 uses the spring mechanism 426 to gradually apply force to the clutch 510 per unit displacement of the bolt 434 and to dampen the force applied on the clutch 510 by the bolt 434. For example, movement of the second carriage 438 compresses the spring mechanisms 426 as the spring mechanisms 426 applies a force on the first carriage 436 causing the first carriage 436 to move in the -y direction. Thus, the force applied by the first carriage 436 in the -y direction is dampened relative to the force applied to the second carriage 438.

[0058] The dynamometers described herein may use dampening mechanisms other than the spring mechanisms described above. For example, hydraulic devices, such as shock absorbers and the like may be used in place of the spring mechanisms .

[0059] Some embodiments of the above-described dynamometers (e.g. , dynamometer 100, dynamometer 300, dynamometer 400, dynamometer 500) may use clutches (e.g. , clutch 110, clutch 310, clutch 410, clutch 510) that are friction clutches. In some embodiments, a cooling system may be included to cool the clutches 110, 310, 410, 510. Reference is made to FIG. 1, which shows a cooling system 140 that may be configured to cool the clutch 110. Other embodiments of the clutches 310, 410, 510 may include similar or identical cooling systems. In some embodiments, the cooling system 140 may provide air to cool the clutch 110. In some embodiments, the cooling system 140 may provide liquid cooling to the clutch 110. Other embodiments of the cooling system 140 may be used.

[0060] Various embodiments of the clutch 110, 310, 410, 510 may be used. The embodiments may include the friction clutches described herein. The following clutch embodiments are described with reference to the clutch 110 of FIG. 1 and are applicable to all the clutches in all the embodiments of the dynamometers described herein. In some embodiments, the clutch 110 may include viscous coupling, such as passively controlled viscous friction. The viscous fluid may be the above-described dampening mechanisms. The viscous friction may be provided by a liquid coupling the clutch input 110A and the clutch output HOB. In some embodiments, the clutch 110 may include an electromagnetic brake or eddy current brake, both of which may be contactless. In these embodiments, the clutch 110 may be frictionless and, thus, may not generate heat, so the cooling system 140 may not be included. In some embodiments, the clutch 110 may include fluid braking to couple the clutch input 110A to the clutch output HOB. Some embodiments of the fluid braking include actively controlled viscous friction, such as electrorheological fluid (ERF) and magnetorheological fluid (MRF) . Thus, the friction in the clutch 110 is dependent on the viscosity of the ERF or MRF, which may be dependent on an electric field or magnetic field applied to the ERF or MRF. Other types of fluid braking may be used. In some embodiments, the electric field or the magnetic field may be controllable to control the viscosity.

[0061] Mechanisms other than the bolt 134 may be used to apply a force to the clutch 110. The following alternative mechanisms may be used in any of the dynamometers described herein. In some embodiments, the bolt 134 and/or the knob 134A may be replaced with a stepper motor. In some embodiments, the stepper motor may replace the knob 134A and may rotate the bolt 134. In other embodiments, the bolt 134 and/or the knob 134A may be replaced with a linear actuator that may be electrostatically (e.g. , comb-drive actuator) or electromagnetically driven. In other embodiments, the bolt 134 and/or the knob 134A may be replaced with a piezoelectric actuator. Such a piezoelectric actuator may be in the form of an inchworm actuator, for example, or a single bulk piezoelectric element that expands or contracts based on a potential applied across at least one axis of the bulk piezoelectric element.

[0062] Additional reference is made to FIG. 6, which illustrates an embodiment of a dynamometer including an actuator assembly 646 (e.g. , a linear actuator) configured to move the motor 102 in the x-direction. In the embodiment of FIG. 6, the actuator assembly 646 may be attached to the frame 606. The actuator assembly 646 may include an actuator 648 configured to move a first member 650A linearly in the x- direction. In the embodiment of FIG. 6, the first member 650A is coupled to a dampening mechanism 652, which is also coupled to a second member 650B. The second member 650B is also coupled to the motor 102. The dampening mechanism 652 may be similar or identical to the spring mechanisms 126 (FIG. 1) and may be configured to dampen force applied by the first member 650A. The dynamometer 600 may include a tachometer 616 that may be substantially similar or identical to the tachometer 116 (FIG. 1) and may be configured to measure the speed of the motor 102.

[0063] Instructions may be transmitted to the actuator 648, which causes the actuator 648 to move the first member 650A in the x-direction. For example, the computer 112 (FIG. 1) may generate instructions that cause the actuator 648 to move the first member 650A in the x-direction. Movement of the first member 650A may be dampened by the dampening mechanism 652. Thus, the force applied to the clutch 110 in the x-direction may be the same or substantially similar to the force applied to the clutch 110 as described in FIG. 1. The torque measured by strain gauge 108 and the speed of the motor 102 measured by the tachometer 616 may be processed by the programs 112C (FIG. 1) to generate data. The data, for example, may be graphs as shown in FIG. 2. The programs 112C may generate other data.

[0064] Additional reference is made to FIG. 7, which illustrates a flowchart depicting a method 700 of operating a dynamometer (e.g. , dynamometers 100, 300, 400, 500, 600) . The method 700 includes, at 702, operating a motor under test (e.g. , motor 102) . The method 700 includes, at 704, coupling the motor under test to a torque measuring device (e.g. , strain gauge 108, rotary torque transducer 408) using a clutch (e.g. , clutch 110, 310, 410, 510) . The method 700 includes, at 706, engaging the clutch by applying a force to the clutch, wherein the force applied to the clutch is dampened by a dampening device (e.g. , spring mechanisms 126, 326, 426) .

[0065] While this disclosure is susceptible to various modifications and alternative forms, specific system and apparatus embodiments and methods thereof have been shown by way of example in the drawings and are described in detail herein. It should be understood, however, that the particular systems, apparatus, or methods disclosed herein are not intended to limit the disclosure or the claims.

Claims

CLAIMS WHAT IS CLAIMED IS:

1. A dynamometer comprising: a torque measuring device configured to measure torque applied to the torque measuring device; a clutch having a clutch input and a clutch output, the clutch output coupled to the torque measuring device and the clutch input configured to be coupled to a motor under test, wherein friction between the clutch input and the clutch output is variable; and a dampening mechanism configured to dampen the friction between the clutch input and the clutch output.

2. The dynamometer of claim 1, wherein the clutch is a friction clutch and wherein the friction between the clutch input and the clutch output is dependent on a force applied between the clutch input and the clutch output.

3. The dynamometer of claim 2, further comprising an actuator configured to apply the force between the clutch input and the clutch output .

4. The dynamometer of claim 2, further comprising a bolt configured to apply the force between the clutch input and the clutch output.

5. The dynamometer of claim 1, wherein the dampening mechanism comprises one or more spring mechanisms.

6. The dynamometer of claim 1, wherein the dampening mechanism includes fluid braking between the clutch input and the clutch output, wherein the friction between the clutch input and the clutch output is dependent on the fluid braking.

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7. The dynamometer of claim 1, wherein the dampening mechanism includes electrorheological fluid between the clutch input and the clutch output, wherein the friction between the clutch input and the clutch output is dependent on the viscosity of the electrorheological fluid.

8. The dynamometer of claim 1, wherein the dampening mechanism includes magnetorheological fluid between the clutch input and the clutch output, wherein the friction between the clutch input and the clutch output is dependent on the viscosity of the magnetorheological fluid.

9. The dynamometer of claim 1, wherein the torque measuring device is a strain gauge.

10. The dynamometer of claim 1, wherein the torque measuring device is a rotary torque transducer.

11. The dynamometer of claim 10, wherein the rotary torque transducer has an input coupled to the motor under test and an output coupled to the clutch output.

12. The dynamometer of claim 1, further comprising a slide, wherein the motor under test is movable on the slide relative to the torque measuring device.

13. The dynamometer of claim 12, further comprising an actuator configured to move the motor under test on the slide, wherein the dampening mechanism is located between the actuator and the motor under test.

14. The dynamometer of claim 1, further comprising a tachometer configured to measure speed of the motor under test .

15. A dynamometer comprising: a torque measuring device configured to measure torque applied to the torque measuring device; a clutch having a clutch input and a clutch output, the clutch output coupled to the torque measuring device and the clutch input configured to be coupled to a motor under test; wherein friction between the clutch input and the clutch output is dependent on force applied between the clutch input and the clutch output; an actuator configured to apply force between the clutch input and the clutch output; a spring mechanism located between the actuator and the torque measuring device, the spring mechanism configured to dampen the force applied on the clutch by the actuator; and a tachometer configured to measure speed of the motor under test.

16. The dynamometer of claim 15, wherein the torque measuring device is a strain gauge.

17. The dynamometer of claim 15, wherein the torque measuring device is a rotary torque transducer.

18. The dynamometer of claim 15, further comprising a slide, wherein the motor under test is movable on the slide relative to the torque measuring device.

19. The dynamometer of claim 15, wherein the clutch is configured to apply a force perpendicular to a rotational axis of the motor under test.

20. A method of operating a dynamometer, comprising: operating a motor under test; coupling the motor under test to a torque measuring device using a clutch; and engaging the clutch by applying a force to the clutch, wherein the force applied to the clutch is dampened by a dampening device.

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