Variable-speed V-belt drive for vehicle

• US 20020119846A1
• Filed: 02/21/2002
• Published: 08/29/2002
• Est. Priority Date: 02/23/2001
• Status: Active Grant

• Current Assignee: Kawasaki Jukogyo Kabushiki Kaisha
• Original Assignee: Kawasaki Jukogyo Kabushiki Kaisha
• Inventors: Fujimoto, Hiroyuki, Kitai, Haruo
• Granted Patent: US 6,733,406 B2
• Time in Patent Office: Days
• US Class Current: 474/14
• CPC Class Codes: F16H 55/56 of which the bearing parts are relatively axially adjustable
• CPC Class Codes: F16H 61/21 Providing engine brake control
• CPC Class Codes: F16H 63/062 electric or electro-mechanical actuating means

Abstract

A variable-speed V-belt drive includes: a drive pulley; a driven pulley including a fixed sheave with a cylindrical shaft and a movable sheave mounted on the cylindrical shaft so that the movable sheave can rotate and axially move; a V belt extended between the drive and driven pulleys; and a pressure mechanism of applying pressure to the movable sheave of the driven pulley. The pressure mechanism includes a helical cam groove formed in one of the cylindrical shaft and the movable sheave of the driven pulley, and a roller mounted on other of the cylindrical shaft and the movable sheave of the driven pulley so that the roller engages with the cam groove. The cam groove has opposite first and second working surfaces. The second working surface has a retaining surface of retaining the roller thereon when the vehicle travels in the engine-braking mode. The variable-speed V-belt drive can maintain the effect of engine brake at a high level even when traveling down a steep hill.

Claims

1. A variable-speed V-belt drive for a vehicle with an engine, comprising:

a drive pulley mounted on a drive shaft;

a thrusting mechanism mounted on the drive shaft and capable of exerting thrust to the drive pulley to vary effective pitch diameter of the drive pulley;

a driven pulley mounted on a driven shaft, the driven pulley including a fixed sheave fixedly mounted on the driven shaft and a movable sheave, the fixed sheave being integrally provided with a cylindrical shaft, the movable sheave being mounted on the cylindrical shaft so that the movable sheave can rotate and axially move on the cylindrical shaft;

a V belt extended between the drive pulley and the driven pulley; and

a pressure mechanism of applying pressure to the movable sheave of the driven pulley, the pressure mechanism including a helical cam groove formed in one of the cylindrical shaft and the movable sheave of the driven pulley, and a roller mounted on other of the cylindrical shaft and the movable sheave of the driven pulley so that the roller engages with the cam groove, the cam groove having opposite side surfaces respectively serving as a first working surface with which the roller engages when the vehicle travels in an engine-driving mode and a second working surface with which the roller engages when the vehicle travels in an engine-braking mode, the second working surface of the cam groove having a retaining surface of retaining the roller thereon when the vehicle travels in the engine-braking mode.

2. The variable-speed V-belt drive according to claim 1, wherein the retaining surface is formed so that the roller is retained at a position displaced from a position for a maximum reduction ratio toward a position for a low reduction ratio.

3. The variable-speed V-belt drive according to claim 1, wherein the second working surface is provided with a recess involving the retaining surface and having a depth equal to about half a diameter of the roller.

4. The variable-speed V-belt drive according to claim 2, wherein the second working surface of the cam groove is provided with a recess involving the retaining surface and having a depth equal to about half a diameter of the roller.

5. The variable-speed V-belt drive according to claim 3, wherein the recess involves the retaining surface and a guide surface, the guide surface extending from the retaining surface and smoothly merging into an end surface of the cam groove on a side of the position for the maximum reduction ratio.

6. The variable-speed V-belt drive according to claim 4, wherein the recess involves the retaining surface and a guide surface, the guide surface extending from the retaining surface and smoothly merging into an end surface of the cam groove on a side of the position for the maximum reduction ratio.

7. A variable-speed V-belt drive for a vehicle with an engine, comprising:

a drive pulley mounted on a drive shaft;

a thrusting mechanism mounted on the drive shaft and capable of exerting thrust to the drive pulley to vary effective pitch diameter of the drive pulley;

a driven pulley mounted on a driven shaft, the driven pulley including a fixed sheave fixedly mounted on the driven shaft and a movable sheave, the fixed sheave being integrally provided with a cylindrical shaft, the movable sheave being mounted on the cylindrical shaft so that the movable sheave can rotate and axially move on the cylindrical shaft;

a V belt extended between the drive pulley and the driven pulley; and

a pressure mechanism of applying pressure to the movable sheave of the driven pulley, the pressure mechanism including a helical cam groove formed in one of the cylindrical shaft and the movable sheave of the driven pulley, and a roller mounted on other of the cylindrical shaft and the movable sheave of the driven pulley so that the roller engages with the cam groove, the cam groove having opposite side surfaces respectively serving as a first working surface with which the roller engages when the vehicle travels in an engine-driving mode and a second working surface with which the roller engages when the vehicle travels in an engine-braking mode, the second working surface of the cam groove including a segment having a large lead angle which is larger than a lead angle of the first working surface.

8. The variable-speed V-belt drive according to claim 7, wherein the segment having the large lead angle extends from a position, which is axially displaced from a position for a maximum reduction ratio in the cam groove toward a position for a low reduction ratio, toward the position for the low reduction ratio.

9. The variable-speed V-belt drive according to claim 7, wherein the segment having the large lead angle extends from a position, which axially coincides with a position for a maximum reduction ratio in the cam groove, toward a position for a low reduction ratios.