Face tooth hydraulic piston brake

A braking mechanism is provided for a hydraulic motor driven wheel utilizing a two-piece design of a hub that rotates by means of a drive shaft. A hydraulic chamber is created on the hub in which a piston resides. The piston is grounded (i.e., non-rotatable relative to the motor housing) in the sealed chamber. The piston face inside of the chamber has a radial set of face teeth. These face teeth are similar to the face teeth inside of the hydraulic chamber. When the chamber is pressurized, the piston face teeth are pushed away from the hub face teeth allowing the hub to freely rotate. When pressure is released from the chamber, a spring, or a number of springs, push the piston into the hub causing it to stop rotating relative to the piston.

FIELD

The present disclosure relates to brakes for mechanical devices, and more particularly, to a face tooth piston brake.

BACKGROUND

Many types of devices require safety brakes that are automatically engaged upon de-actuation of the device and disengaged upon activation of the device. Exemplary technologies that can benefit from this type of device include lawn mowers, all-terrain vehicles, maintenance vehicles, winches, hoists, lifts, as well as other types of recreational and industrial machinery.

SUMMARY

According to the principles of the present disclosure, a brake assembly is provided including a drive member rotatable about an axis. A hub is attached to the drive member with the hub defining a piston chamber therein. A surface of the piston chamber includes a first plurality of face teeth. A piston is non-rotatably disposed within the piston chamber and has a second plurality of face teeth that, in a braking mode, engage the first plurality of teeth. A spring biases the piston axially toward the surface of the piston chamber for causing engagement of the first and second plurality of face teeth. A hydraulic chamber is defined between the piston and the piston chamber to allow the chamber to be supplied with hydraulic fluid for disengaging the face teeth to allow rotation of the hub along with the drive member. Alternative actuation devices can be provided for disengaging the face teeth to allow the drive member to drive the hub. Exemplary actuating devices can include a pneumatic system, a mechanical system, or an electro-mechanical system that can be operated to disengage the safety brake.

DETAILED DESCRIPTION

With reference toFIG. 1, a hydraulic motor10is shown for driving a hub12of a hydraulic controlled vehicle. The hydraulic motor10includes fluid ports14,16that control the operation of the hydraulic motor to provide forward or reverse rotation thereof. Mounting apertures18are provided on the hydraulic motor for mounting the hydraulic motor to a frame structure20of a vehicle as is schematically illustrated inFIG. 2. The hub12can include a plurality of wheel lugs22which allow for mounting of a wheel W (schematically illustrated inFIG. 2) thereon. The hydraulic motor10includes a drive shaft24which extends through the hub12and is secured thereto by a nut26.

With reference toFIG. 2, a cross-sectional view of the hydraulic motor and hub12are shown with details of a brake mechanism30shown therein. The brake mechanism30utilizes a piston32disposed within a piston cavity34of the hub12. The piston cavity34defines an axially facing surface36having a plurality of face teeth38thereon. The piston32includes a second axially facing surface40including a plurality of face teeth42disposed thereon for mating engagement with the face teeth38disposed within the piston cavity34. The piston cavity34, as best shown inFIG. 7, also includes an inner cavity wall44and an outer cavity wall46with the axially facing surface36extending therebetween.

The piston32, as best shown inFIG. 11, includes an outer seal groove50and an inner seal groove52which receive an outer seal ring54and an inner seal ring56, respectively, that provides sealing engagement with the outer cavity wall46and inner cavity wall44of the piston cavity34, as shown inFIGS. 2-4.

The piston32is supported for axial movement within the piston cavity34by a plurality of guide pins60which are secured to the housing of the hydraulic motor. The guide pins60can be threadedly engaged with the hydraulic motor, or otherwise attached thereto either directly or indirectly. The guide pins60further include a spring seat portion62against which a coil spring64can be seated. The coil spring64is disposed between the seat portion62and the piston32. The guide pins60further include a post portion66which is received in a corresponding guide hole68provided in a rear surface of the piston32. The piston32is biased by the springs64in an axial direction so that the face teeth42of the piston32are engaged with the face teeth38within the piston cavity34of the hub12.

As best shown inFIGS. 8-13, the piston32is provided with a fluid passage70and a fluid channel72which bisects the face teeth42whereby the fluid passage70is provided with hydraulic fluid that extends through the fluid passage70and into the fluid channel72creating a hydraulic pressure that axially opposes the biasing force of the springs64to move the piston32axially away from the face teeth38within the piston cavity34. By disengaging the face teeth42of the piston32from the face teeth38within the hub12, the hub12is free to rotate along with the drive shaft24.

It is noted that the hub12includes a tapered aperture80, as best shown inFIGS. 5-7. The tapered aperture80receives the drive shaft24therein while the nut26secures the hub12onto the shaft24. The hub12can include a keyway82communicating with the tapered aperture80to provide a keyed connection with the drive shaft24. The drive shaft24can include a rotor90which is received in the housing of the hydraulic motor10which upon supply of hydraulic fluid in a controlled manner to the hydraulic motor, causes the rotor90to rotate, thereby causing the drive shaft24and hub12to rotate as well. The hydraulic fluid can also be supplied to the fluid passage70within the piston32so as to disengage the safety brake when the hydraulic motor is being operated. When the hydraulic motor10is no longer being operated, the supply of hydraulic fluid for disengaging the safety brake is removed, and the safety brake automatically re-engages to prevent rotation of the hub12and thereby the wheel mounted thereto.

The present disclosure provides a braking mechanism for a hydraulic motor driven wheel utilizing a two-piece design of a hub that rotates by means of a drive shaft24. A hydraulic chamber is created within the hub12in which the piston32resides. The piston32is grounded (i.e., non-rotatable relative to the motor housing) in the sealed chamber. The piston face inside of the chamber has a radial set of face teeth. These face teeth are similar to the face teeth inside of the hydraulic chamber. When the chamber is pressurized, the piston face teeth are pushed away from the hub face teeth allowing the hub to freely rotate. When pressure is released from the chamber, a spring, or a number of springs, push the piston into the hub causing it to stop rotating relative to the piston. It is noted that a pneumatic actuation system can be operated in the same manner as the described hydraulic actuation system.

With reference toFIG. 14, an alternative hydraulic piston brake arrangement is shown for use with a hydraulic motor10for driving a hub112. The hydraulic motor10can include fluid ports (similar to ports14,16shown inFIG. 1) that control the operation of the hydraulic motor to provide forward or reverse rotation thereof. The motor can also be provided with mounting apertures (similar to apertures18shown inFIG. 1) for mounting the hydraulic motor10to a frame structure of a vehicle or other machinery as is desired. The hub112can include wheel lugs for use on a hydraulic controlled vehicle, or alternatively, it can be used in other machinery for operating a hydraulically operated device. The hydraulic motor includes a drive shaft24which extends through the hub112, and is secured thereto by a nut26. The hydraulic motor10and hub112include a brake mechanism130shown therein. The brake mechanism130utilizes an annular piston132disposed against an annular backing plate134that is securely mounted to the motor housing. The backing plate134and piston132define a hydraulic chamber136radially therebetween that is supplied with hydraulic fluid for moving the piston132to a disengaged position against the biasing force of springs138.

As best shown inFIG. 16, the hub112includes a center aperture140that receives the drive shaft24of the motor10therein. The nut26secures the hub112to the drive shaft24. The hub112further includes a plurality of brake teeth142on an axially facing surface144.

The piston132, as best shown inFIGS. 15A and 15B, includes a plurality of brake teeth146which are engageable with the brake teeth142of the hub112. The brake teeth146are disposed on an axial end face of the annular piston132. As shown in the cross-sectional view ofFIG. 14, the piston132includes a seal cavity150therein for receiving a seal152that is disposed on one side of the hydraulic chamber136for engagement with the outer surface154of the backing plate134. The backing plate134includes a second seal cavity156for receiving a second seal158for sealing against an interior surface160of the piston132on an opposite end of the hydraulic chamber136. The hydraulic chamber136includes a first end face in the form of an annular flange162extending radially inward from the piston132. A second end face164of the hydraulic chamber136is disposed on a radially outwardly extending flange166of the backing plate134.

The backing plate134includes a plurality of radially outwardly extending splines168which mate with corresponding inwardly extending splines170on the interior surface of the piston132. The splines168,170allow axial movement of the piston132relative to the backing plate134in response to pressurization of the hydraulic chamber136while preventing relative rotation of the piston132relative to the backing plate134which is fixedly attached to the motor housing.

As shown inFIG. 15B, the piston132is provided with a hydraulic port174which receives pressurized hydraulic fluid therein for moving the piston132axially relative to the backing plate134against the biasing force of the springs138in order to disengage the brake teeth146of the piston132from the brake teeth142of the hub112. When the hydraulic pressure is released, the springs138bias the piston132back to an engaged position so that there is a brake tooth interface between the brake teeth146of the piston132and the brake teeth142of hub112.

When the motor10is supplied with hydraulic fluid for driving the motor, the hydraulic fluid is also supplied to the hydraulic port174to disengage the hydraulic brake to allow the motor10to drive the hub112. When the hydraulic fluid to the motor10is interrupted, the hydraulic fluid that disengages the brake is also halted so that the brake is re-engaged automatically when the motor is not driven. As shown inFIG. 14, the backing plate134can be provided with an annular flange178including a plurality of apertures180for receiving mounting bolts182therein for mounting the backing plate to the motor housing. With the brake arrangement of the embodiment shown inFIGS. 14-16, the seals152and158are provided in a non-rotating environment between the non-rotating backing plate134and piston132, and therefore provide a sealed hydraulic chamber136capable of withstanding high pressures for use in various types of applications. The ability to withstand high pressures within the hydraulic chamber136allows the use of biasing springs138having a high spring rate for providing a strong brake connection.

With reference toFIGS. 17 and 18, a motor and piston brake assembly is shown in which a mechanical actuator is utilized for disengaging the piston brake. In particular, as shown inFIG. 17, a motor10includes a drive shaft24which is connected to a hub12in the same manner as previously described. A piston232is provided with face teeth234which engage corresponding face teeth236on the hub12. A plurality of guide pins60engage and guide the piston232while a plurality of springs64bias the piston232into engagement with the face teeth of the hub12. A mechanical actuator240includes a pull cable242that engages a shift fork244that is received in an annular groove246of the piston232. Accordingly, by actuation of the pull cable242, the shift fork244is pulled in a rightward direction, as illustrated inFIG. 17, so as to oppose the biasing force of the springs64so that the piston232is moved out of engagement with the face teeth236of the hub12. It should be understood that the pull cable242can be connected to various mechanical devices that given an operator a mechanical advantage for overcoming the spring force of the springs64to disengage the piston brake232.

With reference toFIG. 19, an alternative embodiment is shown utilizing an electro-mechanical actuator for disengaging the piston brake. In particular, as shown inFIG. 19, a motor10includes a drive shaft24that is connected to a hub12. The piston232includes face teeth234which engage correspondence face teeth236provided on the hub12. Again, there are a plurality of guide pins which engage apertures in the piston232for guiding the piston232in an axial direction. A plurality of springs64bias the piston232in a leftward direction as illustrated inFIG. 19. An electro-mechanical actuation device200is provided for disengaging the piston brake. The electro-mechanical actuation device200includes an armature202connected to a shift fork204that engages the piston232. A coil206is provided within a core208and when supplied with a current, causes the armature202to move in a rightward direction as illustrated inFIG. 19, thus, causing the piston232to move out of engagement with the face teeth236of the hub12. Therefore, the hub12is free to rotate along with the drive shaft24. Upon removing the current supply to the coil206, the springs64bias the face teeth234of the piston232back into engagement with the face teeth236of the hub12.

With reference toFIGS. 20-22, a motor and piston brake assembly is shown in which a cam actuator is utilized for disengaging the piston brake. In particular, as shown inFIG. 20, a motor10includes a drive shaft24which is connected to a hub312by a nut26in the same manner as previously described. A piston332is provided with face teeth334(FIG. 21) which engage corresponding face teeth336on the hub312. The piston332is axially biased into braking engagement with the hub312by springs338as best shown inFIG. 22. The piston332includes a plurality of cam surfaces340spaced circumferentially around the piston332. A plurality of cam members342are mounted to an actuator ring344for moving the cam members342between engaged and disengaged positions with the cam surface340.

By slight rotation movement of the actuator ring344, the cam members342can be caused to ride up the cam surfaces340to cause axial movement of the piston332out of braking engagement with the hub312. By returning the actuator ring344to a disengaged position, the cam members342ride downward along the cam surfaces340so that the biasing force of the spring338bias the piston332into braking engagement with the hub312. The slight rotational movement of the actuator ring344allows engagement and disengagement of the brake during and after operation of the motor10. Operation of the actuator ring344can be performed by mechanical, electromechanical, hydraulic, or other known operating techniques.

It is noted that the brake mechanism shown in the embodiment ofFIGS. 20-22is a normally applied braking system wherein the piston332is normally braked against the hub312. In order to disengage the brake, the actuator ring344is driven to cause the cam members342to move up the cam surfaces340to draw the teeth334of the piston332away from engagement with the teeth336on the hub312.

According to an alternative embodiment, as illustrated inFIGS. 23-26, a cam actuated system is provided in which the brake is normally in an unapplied condition, and the brake can be actuated to be engaged by the cam system. In particular, as shown inFIG. 23, a motor10includes a driveshaft24which is connected to a hub412by a nut26in the same manner as previously described. A piston432is provided with face teeth434which engage corresponding face teeth436on the hub412. A plurality of guide pins460engage and guide the piston432while a plurality of springs464(FIG. 24) bias the piston432out of engagement with the teeth of the hub412. A cam actuator plate440includes a plurality of cam surfaces442which engage a rear surface of the piston432. The rear surface of the piston432includes a cam surface444which opposes the cam surfaces442of the actuator440. For causing engagement of the brake, the actuator440is rotated to cause the cam surfaces442to ride upward along the cam surfaces444on the rearward surface of the piston432to cause axial movement of the piston432into braking engagement with the brake teeth436on the hub412. When the actuator440is rotated so that the cam surfaces442ride downward along the cam surfaces444of the piston432, the springs464cause the piston432to disengage the brake teeth436on the hub412. The piston432is non-rotatably mounted to the motor housing by the guide pins460, and therefore, provide a braking force when engaged with the brake teeth436of the hub412.

With reference toFIG. 27, a winch500is shown incorporating a hub brake according to the principles of the present disclosure. The winch500includes a motor502which provides driving torque to a drive shaft504. The drive shaft504is connected to a gear box506which can include one or more planetary gear stages. In the embodiment shown, first and second planetary gear stages508,510are illustrated. The function and operation of the planetary gear stages508,510are generally well known in the art. The planetary carrier512of the second planetary gear stage510provides a splined connection to the drum514at spline connection516.

Upon normal operation, the motor502drives the drive shaft504which provides input torque to the gear box506and the drum514is driven by the output spline connection516of the gear box506. According to the principles of the present disclosure, a hub520is mounted to the drive shaft504. The hub520includes face teeth disposed within a piston chamber in the same manner as described previously. A piston522is disposed within the piston chamber and includes face teeth which engage the face teeth within the hub520. A plurality of guide pins524are mounted to a drum support526and guidingly engage the piston522for axial movement while preventing rotational movement of the piston522. A plurality of springs528bias the piston522in the direction for engagement with the face teeth of the hub520. A brake housing or cover530can be provided for mounting the motor502to the drum support526.

The motor502can be a hydraulic motor or an electric motor. The piston522can be engaged by an actuation device that can include a hydraulic, mechanical, pneumatic, or electro-mechanical actuation device for disengaging the piston522from the face teeth of the hub520.

With reference toFIG. 28, when the face teeth of the piston522are engaged with the face teeth of the hub520, the piston522prevents the hub520from rotating, thus providing a brake for the winch drum514. The piston522is non-rotatable relative to the drum support526and the drum support526is mounted to an exterior structure to prevent rotation of the drum support. Thus, while the hub520is effectively braked, the drive shaft504and drum514are also braked. Upon actuation of the motor502, the piston522can be disengaged from the hub520to allow the drive shaft and hub to freely rotate.