Safety control system for motorized resistance equipment utilizing one-way clutches

Abstract

An exercise apparatus includes a rope wrapped around a spindle having a one-way clutch rotatably mounted on a driveshaft. The driveshaft is driven by a motor controlled by a motor controller. The controller is capable of driving and braking the motor such that the driving torque and the braking torque can be set at different values to ensure the safety of the apparatus and user.

Claims

1. A safety control system for motorized exercise equipment utilizing a one-way clutch mounted on a driveshaft having a flexible element wound about a spindle, the system comprising: a motor for providing power to said driveshaft for rotation at a first speed; a current controller for maintaining a motor torque limit in two or more motor states whereby said limit is different between said states; a power state having a first motor torque limit whereby said spindle idles about said driveshaft; and a braking state having a second motor torque limit upon a user engaging said flexible element and rotating said spindle at a second speed greater than said first speed whereby said clutch engages said driveshaft, and said braking state is maintained in response to said second speed.

2. The system as defined in claim 1 wherein said controller gradually changes between said states.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present disclosure will be more fully understood by reference to the following detailed description of one or more preferred embodiments when read in conjunction with the accompanying drawings, in which like reference characters refer to like parts throughout the views and in which:

(2) FIG. 1 is a perspective view of the component parts of a safety control system for an exercise machine according to the principles of an embodiment of the present disclosure.

(3) FIG. 2 is a perspective view of the component parts of a safety control system for an exercise machine according to the principles of an alternate embodiment of the present disclosure.

(4) FIG. 3 is a perspective view of the component parts of a safety control system for an exercise machine according to the principles of an alternate embodiment of the present disclosure.

(5) FIG. 4A is a side view of the component parts of a safety control system for an exercise machine according to the principles of an alternate embodiment of the present disclosure in the open state.

(6) FIG. 4B is a side view of the component parts of a safety control system of FIG. 4A in the closed state.

(7) FIG. 5A is a side view of the component parts of a safety control system for an exercise machine according to the principles of an alternate embodiment of the present disclosure in the closed state.

(8) FIG. 5B is a side view of the component parts of a safety control system in FIG. 5A in the closed state.

(9) FIG. 6 is a circuit diagram of a safety circuit for use in the safety control system for motorized resistance equipment utilizing a one-way clutch according to the principles of the present disclosure.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

(10) One or more embodiments of the subject disclosure will now be described with the aid of numerous drawings. Unless otherwise indicated, use of specific terms will be understood to include multiple versions and forms thereof.

(11) The component parts of a safety control system 10 for motorized resistance equipment utilizing a one-way clutch are illustrated in the perspective view of FIG. 1. Here the user engageable end 12 of a flexible element 14, such as a cable, line or rope, is wrapped around a spool or spindle 16. The spindle 16 may utilize a recoil device 18, such as a bungee cord wrapped in the opposite direction, or other mechanism or recoil motor. The rotational bearing of the spindle 16 includes a one-way clutch 20 and the spindle assembly is mounted on a shaft 22 driven by a motor 24. The motor 24 uses a controller 26 capable of providing power (power state) to the motor, as well as braking (braking state) the motor. The power state is used when there is a load on the motor, and the braking state is used when there is an overrun load on the motor.

(12) One method of operation of the system of FIG. 1 includes commanding the controller 26 to maintain a constant motor direction 28 and speed. When the user engageable end 12 is left at rest, the spindle 16 idles on the drive shaft 22, and the speed controller 26 commands the motor 24 to rotate at a constant speed. This is the power state. When the user engageable end 12 is pulled with sufficient speed and force to exceed the commanded motor speed, the one-way clutch 20 locks onto the driveshaft 22 and the force of the user's actions attempts to accelerate the motor rotation. The motor controller 26 senses this acceleration and commands a braking state. When the user releases pressure on the rope 14, the spindle 16 slows and the one-way clutch 20 disengages from the driveshaft 22 at which point the recoil mechanism 18 can retract the user engageable end 12.

(13) During proper operation, this system allows the user to pull with any force, yet as soon as pulling is stopped, only the recoil force is experienced, pulling the user engageable end away from the user. For some applications it may be desirous to specify a motor and controller combination with enough braking torque to withstand a significant pull from an athlete (e.g. 800 lbs.). In any event, care must be taken, however, in designing the system to provide for safe operation.

(14) In one embodiment, the speed controller, within the motor controller 26, can independently limit current flow to the motor 24 for the power state and the braking state. Current flow through the motor is very low (e.g. less than one amp) during the power state, as the only resistance to rotation is from the power transfer components (e.g. drive belt) and the bearings in the system. Depending on the force applied to the user engageable end 12 of the rope 14, the (absolute value of the) current flow through the motor 24 during braking state can be very high (e.g. −5 amps).

(15) A low current limit (e.g. 1 amp) is applied to the power state, while a high current limit (e.g. 8 amps) is applied to the braking state. Switching from one state to another can be instantaneous or ramped in order to minimize awareness of the transition by the user. In the event of a clutch 20 failure or other wrapping scenario such that the flexible element 14 becomes pulled rather than released by the motor 24, the total force of pull will be limited to a low value (e.g. 10 lbs.) due to the low current limit set during the power state.

(16) An alternate embodiment of the safety control system for motorized resistance equipment utilizing a one-way clutch is shown in FIG. 2. Here, a force sensor (e.g. strain gauge, load cell, spring switch, current sensor, etc.) is used to measure the force applied to the flexible element 14; and a flexible element direction sensor (e.g. rotary encoder, linear encoder, mechanical switch, etc.) is used to determine whether the flexible element 14 is moving in at least a first direction.

(17) During normal use, the flexible element 14 is pulled in the first direction with deliberate force, typically greater than 5 lbs. When the flexible element 14 is released back in the second direction, the recoil system 18 takes up the slack and the measured force is typically less than 3 lbs. A logic control circuit within the controller 26 monitors both the force and direction information. If the flexible element 14 is being pulled in the first direction, the system operates normally. If the flexible element moves in the second direction, and the force detected is above a threshold (e.g. 5 lbs.), it is assumed that there is a clutch failure or other wrapping scenario, and a failure command is executed. The failure command either temporarily or permanently reduces the ability of the motor 24 to supply torque to the spindle 16. This can include reducing the current limit to the motor 24, slowing the motor 24, mechanically disengaging the motor 24 from the spindle 16, braking the motor 24, removing power completely from the motor 24, and mechanically stopping movement of the flexible element 14.

(18) Another alternate embodiment of the safety control system for motorized resistance equipment utilizing a one-way clutch is shown in FIG. 3. Here, a small motor is used in combination with a brake 34. The motor 24 is designed to provide enough torque to overcome the friction caused by the mechanical components, such as the bearings and the one-way clutch 20. When the user engageable end 12 of the flexible element 14 is pulled and the spindle 16 begins to accelerate, the brake 34 is automatically applied to control the speed of the spindle 16. Because the motor 24 only applies to a low torque, a wrap or clutch failure will not result in injury to the user.

(19) A further embodiment of the safety control system for motorized resistance equipment utilizing a one-way clutch is shown in FIG. 4. Here, an automatic brake mechanism is employed. This can take the form of a spring-loaded cam mechanism 36 or the like built around the flexible element 14 prior to it reaching the user engageable end 12. A first pulley 38 is mounted on a spring-loaded pivot arm 40. A second pulley 42 is fixed to a frame 44 beneath the first pulley 38. A second pivot arm 46 is mounted to the frame 44 and attached to the spring-loaded pivot arm 40 with a linkage 48. A one-way locking mechanism 50 is mounted to the second pivot arm 46. The flexible element 14 is fed over the first pulley 38 and under the second pulley 42 such that it exits beneath the one-way locking mechanism 50. The spring 52 is chosen so that when there is a force greater than the recoil force on the flexible element 14 (e.g. greater than 10 lbs.), the first lever arm 40 compresses the spring 52 and causes the second lever arm 46 to move down via the linkage 48 causing the one-way locking mechanism 50 to come in contact with the flexible element 14.

(20) When the user pulls with a force greater than 10 lbs., for example, the one-way locking mechanism 50 presses against the flexible element 14. Since the flexible element is moving in the non-locking direction of the one-way locking mechanism 50, it is able to pass unhindered. If there is a malfunction and the flexible element 14 is pulled into the machine with greater than 10 lbs. of force, the one-way locking mechanism 50 will come in contact with the flexible element 14 and prevent it from being retracted.

(21) Yet another further embodiment of the safety control system for motorized resistance equipment utilizing a one-way clutch is shown in FIG. 5. Here, a cam is used to disconnect the power from the drive motor during failure mode. A pulley 38 is mounted on a spring-loaded pivot arm 40. A second pulley 42 is fixed to a frame beneath the first pulley 38. A second pivot arm 46 is mounted to the frame and attached to the spring-loaded pivot arm 40 with a linkage 48. An electrical switch 54 is mounted to the second pivot arm 46. The flexible element 14 is fed over the first pulley 38 and under the second pulley 42 such that it exits beneath the electrical switch 54. The spring 52 is chosen so that when there is a force greater than the recoil force on the flexible element 14 (e.g. greater than 10 lbs.), the first lever arm 40 compresses the spring 52 and causes the second lever arm 52 to move down via the linkage 48 causing the electrical switch 54 to come in contact with the flexible element 14. The electrical switch 54 directs power to the drive motor and/or brake and is preset in the “on” direction. If the flexible element 14 is pulled in a first direction with greater than 10 lbs., for example, the linkage 48 brings the switch 54 in contact with the flexible element 14 and the switch remains “on”. If the flexible element 14 is pulled in a second direction with greater than 10 lbs., the switch is moved to the “off” position and power is removed from the drive motor 24 or a brake is activated.

(22) Turning now to the safety circuits 56 of FIG. 6. First, circuit 58 monitors the motor current with U10. The current is monitored continuously by U5 with U5 output smoothed by R15 and C17 so quick transits will not activate the safety comparator circuit. The output voltage of this circuit is then fed into the comparator circuit (U6) with the trip point set with R45 and R46. If there is a malfunction causing the flexible element to be pulled into the machine and the motor current reaches the setpoint of U6, the relay K1 is activated and thus disables the main motor controller by opening the E1 (motor enable) and turning off the motor. It will be understood that other depowering and braking methods may also be deployed.

(23) The direction of rotation of a motor can be determined by monitoring the voltage flow through the motor. Circuit 60 monitors drive voltage looking for the voltage to go negative indicating a failure. This circuit monitors the main motor's drive voltage with U10. The signal voltage output of U10 is smoothed by R44 and C33 so fast transits will not activate the comparator circuit. This voltage is then fed into the comparator circuit U11. The trip point for this circuit is set with R45 and R46. If there is a motor controller failure, or other malfunction which would cause the motor to reverse direction, the motor voltage will reach the set trip point and U11 will activate K1 disabling the main motor controller by opening the E1 (motor enable) and turning off the motor. It will be understood that other depowering and braking methods may also be deployed.

(24) When using the described system, there may be times when a user is pulling with significant force, or simply “trusting” the machine by leaning back and knowing that as long as the flexible element is paid out at a fixed speed, the user will be in a “controlled fall” which he/she can manage as part of the desired body movement. However, if the flexible element were suddenly released, as might happen for example during a power failure, the user would run the risk of falling.

(25) In one embodiment, the regenerative nature of the motor is used as a brake in the event of power loss or other malfunction. When power loss or a malfunction is detected, a switching relay is used to disconnect the motor from the drive, and put a direct short, or low value resistance across the motor leads. This will cause the motor to become a generator and maintain a torque thereby controlling the payout of the flexible element.

(26) It will be understood that an external brake, as known in the art (e.g. StepperOnline DC Electromagnetic 24V Brake, etc.) can be used instead of the regenerative nature of the above-described motor. Indeed, it will be appreciated that numerous types of systems, methods and devices may be employed for such change in motor speed.

(27) Although the above described brakes are an effective means of slowing the payout of the flexible element, there may be times when a user is moving at a very fast speed with low force production where it can be dangerous to brake aggressively. For example, if the user is running at full speed while wearing a vest or belt tied to the flexible element, a sudden braking of the system might injure the user due to the sudden stop.

(28) In one embodiment, a circuit monitors the voltage at the motor armature. Because armature voltage varies with motor speed, the equipment designer can choose a threshold voltage (speed) above which it is not desirable to activate a brake in the event of a power failure. A power detecting device, such as a relay, works in conjunction with a voltage comparator. The power detecting device utilizes a capacitor, battery, or other temporary power source which will temporarily keep power to the circuit in the event of a power failure If a power failure is detected, the voltage comparator is monitored to either do nothing in the event the voltage (motor speed) is above a threshold, or activate the brake if the voltage (motor speed) is below a threshold. This method can also use a graduated brake varying from zero to full braking. In this case, a variable resistor, or set of resistors can be selected based on the speed of the system.

(29) The foregoing detailed description has been given for clearness of understanding only and no unnecessary limitations should be understood therefrom. Accordingly, while one or more particular embodiments of the disclosure have been shown and described, it will be apparent to those skilled in the art that changes and modifications may be made therein without departing from the invention if its broader aspects, and, therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of the present disclosure.