Micro-traction drive unit and hydrostatic transmission

Patent metadata

Field	Value
Publication number	US-10364875-B2
Application number	US-201615528994-A
Country	US
Kind code	B2
Filing date	Feb 17, 2016
Priority date	Mar 3, 2015
Publication date	Jul 30, 2019
Grant date	Jul 30, 2019

Abstract

A micro-traction drive unit according to the present invention includes an inner ring, an outer ring, a plurality of rolling elements, a retainer, a micro-traction drive case and a power-transmitting shaft coaxial with the inner ring and incapable of relative rotation around an axis to the retainer. An opposite end of the power-transmitting shaft from the inner ring forms an input end operatively connected to a driving source. An input end of the pump shaft is detachably connected to a central hole of the inner ring in a state incapable of relative rotation around the axis via the access opening of the micro-traction drive case by connecting the micro-traction drive case to the HST case so as to surround the input end of the pump shaft of the HST.

First claim

What is claimed is:

1. A micro-traction drive unit capable of attachment to a hydrostatic transmission (“HST”) in which a hydraulic pump and a hydraulic motor that are fluidly connected to each other and at least one of which is a variable volume type are respectively supported by a pump shaft and a motor shaft so as to be incapable of relative rotation and are accommodated in an HST case, and an input end of the pump shaft extends outward from the HST case, the micro-traction drive unit comprising:
an inner ring;
an outer ring;
a plurality of rolling elements;
a retainer retaining the plurality of rolling elements;
a micro-traction drive case accommodating the inner ring, the outer ring, the plurality of rolling elements, and the retainer, and removably connected to the HST case such that the micro-traction drive case is directly connected to the HST case, wherein the micro-traction drive case comprises a continuous peripheral wall that surrounds at least the inner ring, the outer ring, the plurality of rolling elements, and the retainer; and
a power-transmitting shaft supported by the micro-traction drive case and incapable of rotation relative to the retainer and positioned coaxially with the inner ring, wherein
an opposite end of the power-transmitting shaft from the inner ring extends outward from the micro-traction drive case so as to form an input end operatively connected to a driving source;
the micro-traction drive case has an access opening on a side that faces the HST case when connected to the HST case; and
the input end of the pump shaft is removably connected via the access opening to a central hole of the inner ring so as to be incapable of rotation relative to the inner ring, wherein the micro-traction drive case is directly connected to the HST case in such a manner that the peripheral wall of the micro-traction drive case surrounds the input end of the pump shaft.

2. The micro-traction drive unit according to claim 1 , wherein
the retainer has a ring-shaped retainer body that is positioned more toward one side in a rotational axis direction of the inner ring than the rolling elements are and radially between the inner ring and the outer ring in reference to the rotational axis of the inner ring and that is incapable of relative rotation around the axis with respect to the power transmission shaft, and a ring-shaped fixing member that is positioned on an opposite side of the rolling elements from the retainer body in the rotational axis direction of the inner ring and radially between the inner ring and the outer ring in reference to the rotational axis of the inner ring;
an end face of the retainer body facing the fixing member has a plurality of retainer-body-side depressions that are open toward the fixing member in the rotational axis direction of the inner ring and are disposed along a circumferential direction;
an end face of the fixing member facing the retainer body has a plurality of fixing-member-side depressions that are open toward the retainer body in the rotational axis direction of the inner ring and are disposed in the circumferential direction; and
the retainer body and the fixing member are connected to each other at a retainer-body-side connecting region positioned between one retainer-body-side depression and another retainer-body-side depression circumferentially adjacent thereto and a fixing-member-side connecting region of the fixing member corresponding to the retainer-body-side connecting region, such that the plurality of rolling elements are brought into contact with the inner ring and the outer ring and retained by the retainer-body-side depressions and the fixing-member-side depressions.

3. The micro-traction drive unit according to claim 2 , wherein
the retainer-body-side depressions and the fixing-member-side depressions as viewed in a circumferential cross-section have a deepest circular arc region positioned in a deepest area of the corresponding depression, a first sloped region extending toward one side in a circumferential direction from an end on one side in the circumferential direction of the deepest circular arc region, and a second sloped region extending toward the other side in the circumferential direction from an end on the other side in the circumferential direction of the deepest circular arc region; and
the deepest circular arc region has approximately the same curvature as the rolling elements, and, among the first and second sloped regions, a sloped region on a side where the sloped region is brought into contact with the rolling elements when rotation of the retainer is transmitted in an accelerated manner to the inner ring has a larger curvature than the curvatures of the rolling elements.

4. The micro-traction drive unit according to claim 3 , wherein
the micro-traction drive case is connected to the HST case so as to define an inner space that is separated in a fluid-tight manner from an inner space of the HST case; and
the micro-traction drive case has an introduction hole for introducing traction oil into the inner space.

5. The micro-traction drive unit according to claim 2 , wherein
the micro-traction drive case is connected to the HST case so as to define an inner space that is separated in a fluid-tight manner from an inner space of the HST case; and
the micro-traction drive case has an introduction hole for introducing traction oil into the inner space.

6. The micro-traction drive unit according to claim 2 , further comprising:
a plurality of cramping pins disposed on the retainer body; and
a plurality of holes disposed on the fixing member, wherein the cramping pins are inserted into the holes when the fixing member and the retainer body are connected.

7. The micro-traction drive unit according to claim 1 , wherein
the micro-traction drive case is connected to the HST case so as to define an inner space that is separated in a fluid-tight manner from an inner space of the HST case; and
the micro-traction drive case has an introduction hole for introducing traction oil into the inner space.

8. A hydrostatic transmission (“HST”), wherein a hydraulic pump and a hydraulic motor, fluidly connected to each other and at least one of which is a variable volume type are respectively supported by a pump shaft and a motor shaft so as to be incapable of relative rotation and are accommodated in an HST case, the hydrostatic transmission comprising:
a micro-traction drive unit having an inner ring, an outer ring, a plurality of rolling elements, a retainer retaining the plurality of rolling elements, a power-transmitting shaft incapable of rotation relative to the retainer and positioned coaxially with the inner ring, and a micro-traction drive case accommodating the inner ring, the outer ring, the plurality of rolling elements, and the retainer and supporting the power-transmitting shaft so as to be rotatable around its axis,
wherein the micro-traction drive case comprises a continuous peripheral wall that surrounds at least the inner ring, the outer ring, the plurality of rolling elements, and the retainer,
wherein the micro-traction drive case is directly connected to the HST case, and
wherein an opposite end of the power-transmitting shaft from the inner ring extends outward from the micro-traction drive case so as to form an input end operatively connected to a driving source, and
wherein the inner ring is connected to the pump shaft so as to be incapable of relative rotation and the micro-traction drive case surrounds an input end of the pump shaft.

9. The hydrostatic transmission according to claim 8 , wherein
an inner space of the micro-traction drive case and an inner space of the HST case are separated from each other in a fluid-tigh

Assignees

• Kanzaki Kokyukoki Mfg Co Ltd

Inventors

• Iwaki Koji
• Miyake Etsuo

Classifications

• F16H39/14

  with cylinders carried in rotary cylinder blocks or cylinder-bearing members · CPC title

• F15B11/08

  with only one servomotor · CPC title

• F15B2211/20546

  variable capacity · CPC title

• F16H39/10

  with cylinders arranged around, and parallel or approximately parallel to the main axis of the gearing · CPC title

• F16H47/04 Primary

  the mechanical gearing being of the type with members having orbital motion · CPC title