Wheel Motor Device

Abstract

A wheel motor device according to the present invention includes a hydraulic motor main body forming an HST in cooperation with the hydraulic pump main body, a motor shaft supporting the hydraulic motor main body in a relatively non-rotatable manner, a speed-reduction gear mechanism for reducing the speed of the rotational power output from the motor shaft, a first output member for outputting the rotational power whose speed has been reduced by the speed-reduction gear mechanism toward a corresponding first driving wheel, a casing accommodating the hydraulic motor main body and the speed-reduction gear mechanism, and a brake mechanism selectively and operatively applying a brake force to the first output member. The brake mechanism includes a brake shaft supported by the casing, a speed-increasing gear mechanism for increasing the speed of the rotational power output from the motor shaft and operatively transmitting the same to the brake shaft, and a brake unit for selectively and operatively applying the brake force to the brake shaft.

1 . A wheel motor device applied in a working vehicle including a driving power source, a hydraulic pump main body operatively driven by the driving source and a pair of first and second driving wheels facing to each other along a widthwise direction of the vehicle, the wheel motor device comprising a hydraulic motor main body forming an HST in cooperation with the hydraulic pump main body, a motor shaft supporting the hydraulic motor main body in a relatively non-rotatable manner, a speed-reduction gear mechanism for reducing the speed of the rotational power output from the motor shaft, a first output member for outputting the rotational power whose speed has been reduced by the speed-reduction gear mechanism toward the corresponding first driving wheel, a casing accommodating the hydraulic motor main body and the speed-reduction gear mechanism, and a brake mechanism selectively and operatively applying a brake force to the first output member, the wheel motor device being characterized in that,
 the brake mechanism includes a brake shaft supported by the casing, a speed-increasing gear mechanism for increasing the speed of the rotational power output from the motor shaft and operatively transmitting the same to the brake shaft, and a brake unit for selectively and operatively applying the brake force to the brake shaft.   
   
   
       2 . A wheel motor device according to  claim 1 , wherein
 the casing includes a motor case which supports the motor shaft at a position displaced from a rotational axis line of the first driving wheel in such a manner that the motor shaft is substantially parallel to the rotational axis line of the first driving wheel and is rotatable around its axis line and which accommodates the hydraulic motor main body supported by the motor shaft, and a gear case connected to a side of the motor case which is close to the first driving wheel, the gear case supporting the first output shaft so as to be positioned coaxially with the rotational axis line of the first driving wheel in a state of being rotatable manner around its axis line and accommodating the speed-reduction gear mechanism,   the brake shaft is supported in a rotatable manner around its axis line by the gear case at a position displaced from the first driving wheel around the rotational axis line of the first driving wheel, in such a manner that the brake shaft is substantially parallel to the rotational axis line of the first driving wheel and an end portion of the brake shaft on a side away from the first driving wheel is extended outward from the gear case, and   the brake unit includes a brake disk supported by the outwardly-extending end portion of the brake shaft in a relatively non-rotatable manner, and is configured so as to selectively apply the brake force to the brake disk on the basis of an operation from the outside.   
   
   
       3 . A wheel motor device according to  claim 2 , wherein the gear case is capable of supporting the brake shaft at plural positions around the rotational axis line of the first output member. 
   
   
       4 . A wheel motor device according to  claim 3 , wherein the plural positions include first and second portions which are symmetrical to each other with an imaginary vertical plane as a reference, the imaginary vertical plane passing through the rotation axis line of the first output member. 
   
   
       5 . A wheel motor device according to  claim 2 , wherein the brake unit includes a mounting stay detachably connected to the gear case, a brake operation shaft supported in a rotatable manner around its axis line by the mounting stay in a state that its axis line extends substantially parallel to a disk surface of the brake disk and its first end portion having a non-circular cross-sectional shape overlaps with the brake disk as viewed along the rotational axis line of the brake disk, and a push-side brake pad supported by the first end portion in such a manner as to come close to or separate from the brake disk in accordance with the rotation of the brake operation shaft about the axis line. 
   
   
       6 . A wheel motor device according to  claim 5 , wherein the brake unit further includes a fixed-side brake pad detachably supported by the gear case in such a manner as to face to the push-side brake pad across the brake disk. 
   
   
       7 . A wheel motor device according to of  claim 2 , further comprising a brake-shaft-side coupling supported in a relatively non-rotatable manner by a portion of the brake shaft which is away from the first driving wheel than the brake disk, wherein
 the brake-shaft-side coupling has a concave/convex engagement portion at an end surface on a side opposite from the corresponding first driving wheel, the concave/convex engagement portion being opened toward the other second driving wheel.   
   
   
       8 . A wheel motor device according to  claim 1 , further comprising a second output member which is operatively connected trough the speed-reduction gear mechanism to the motor shaft and which outputs a driving force toward the second driving wheel. 
   
   
       9 . A wheel motor device according to  claim 8 , wherein,
 the first and second output members are positioned coaxially with each other,   the wheel motor device further comprises a differential gear mechanism including a ring gear operatively connected to the motor shaft, first and second side bevel gears respectively supported on the first and second output members in a relatively non-rotatable manner, a pinion shaft rotating along with the ring gear, and a bevel pinion supported on the pinion shaft in a relatively rotatable manner in a state of being engaged with the first and second side bevel gears,   a driving-side gear with a small diameter provided on the motor shaft so as to engage with the ring gear forms the speed-reduction gear mechanism in cooperation with the ring gear, and   a driven-side gear with a small diameter provided on the brake shaft so as to engage with the ring gear forms the speed-increasing gear mechanism in cooperation with the ring gear.   
   
   
       10 . A wheel motor device according to  claim 1 , wherein,
 the motor shaft is displaced from the rotational axis line in a state of being substantially parallel to the rotational axis line,   the first output member is disposed coaxially with the rotational axis line of the first driving wheel,   the speed-reduction gear mechanism includes a driving-side gear with a small diameter which is provided on the motor shaft in a relatively non-rotatable manner, and an output gear with a large diameter which is provided on the first output member in a relatively non-rotatable manner and which is engaged with the driving-side gear, the output gear being embodied by an internal gear,   the brake shaft is provided with a driven-side gear with a small diameter which is engaged with the output gear, and   the output gear and the driven-side gear form the speed-increasing gear mechanism.