Working Vehicle with HST

• US 20100043419A1
• Filed: 10/11/2007
• Published: 02/25/2010
• Est. Priority Date: 01/23/2007
• Status: Active Grant

• Current Assignee: Yanmar Power Technology Co., Ltd. (Yanmar Holdings Co., Ltd.)
• Original Assignee: Yanmar Company Limited (Yanmar Holdings Co., Ltd.)
• Inventors: Hayashi, Keiichi, Yuki, Hidehiro, Nomura, Hitoshi
• Granted Patent: US 8,261,543 B2
• Time in Patent Office: Days
• US Class Current: 60/328
• CPC Class Codes: B60K 17/10 of fluid gearing of fluid clutches B60K17/02
• CPC Class Codes: B60W 10/02 including control of driveline clutches
• CPC Class Codes: B60W 10/103 of fluid type
• CPC Class Codes: B60W 2510/0208 Clutch engagement state, e.g. engaged or disengaged
• CPC Class Codes: B60W 2520/10 Longitudinal speed
• CPC Class Codes: B60W 30/18072 Coasting
• CPC Class Codes: B60W 50/029 Adapting to failures or work around with other constraints, e.g. circumvention by avoiding use of failed parts
• CPC Class Codes: B60Y 2200/221 Tractors
• CPC Class Codes: F16H 61/431 Pump capacity control by electro-hydraulic control means, e.g. using solenoid valves
• CPC Class Codes: F16H 61/47 for achieving a target output speed

Abstract

A working vehicle with an HST in which over-rotation of a hydraulic pump in the HST or the pump input shaft thereof is prevented when a main clutch is disconnected during a run. When a main clutch connection/disconnection detection means (112) detects (S2) the disconnection state of the main clutch (22) during a run, a control means (110) judges (S3) whether a vehicle speed detected by a vehicle speed detection means (116) is at least a set speed or not, and if the vehicle speed is at least the set speed, the movable swash plate (55) of the hydraulic pump (51) in an HST (50) is controlled to sustain it at the current inclination angle (S4).

Claims

1. A working vehicle with a hydraulic stepless transmission (HST) having a hydraulic pump and a hydraulic motor, comprising:

a main clutch disposed between the HST and an engine;

a power transmission means disposed between the HST and a wheel;

an actuator changing slant angle of a movable swash plate of the hydraulic pump of the HST; and

a control means controlling actuation of the actuator, wherein;

a main clutch connection/disconnection detection means detecting connection status of the main clutch and a vehicle speed detection means detecting vehicle speed are provided,

the main clutch connection/disconnection detection means and the vehicle speed detection means are connected to the control means,

when the vehicle speed detected by the vehicle speed detection means is not less than a set speed at a time of disconnecting the main clutch, the slant angle of the movable swash plate of the hydraulic pump is held at an angle at which the main clutch is disconnected, and

when the vehicle speed detection means does not detect the vehicle speed, a slant angle of the movable swash plate of the hydraulic pump is controlled so that vehicle speed is smaller than the set speed.

2. The working vehicle with the HST as set forth in claim 1, wherein when the vehicle speed detected by the vehicle speed detection means is less than the set speed while the main clutch is disconnected, the movable swash plate of the hydraulic pump is rotated to a neutral position.

3. The working vehicle with the HST as set forth in claim 1, wherein a sub transmission is provided in the power transmission means, and in a case that the vehicle speed detection means does not detect the vehicle speed, when the sub transmission is at a low speed position, the slant angle of the movable swash plate of the hydraulic pump can be changed suitably.

4. The working vehicle with the HST as set forth claim 1, wherein the vehicle speed detection means comprises a rotation detection means, which outputs a pulse signal corresponding to rotation of a drive shaft of the wheel, and a conversion means, which outputs a voltage corresponding to a frequency of the pulse signal of the rotation detection means.

5. The working vehicle with the HST as set forth in claim 1, further comprising a warning means which warns when vehicle speed is not detected by the vehicle speed detection means.

7. The working vehicle with the HST as set forth in claim 2, wherein the vehicle speed detection means comprises a rotation detection means, which outputs a pulse signal corresponding to rotation of a drive shaft of the wheel, and a conversion means, which outputs a voltage corresponding to a frequency of the pulse signal of the rotation detection means.

8. The working vehicle with the HST as set forth in claim 3, wherein the vehicle speed detection means comprises a rotation detection means, which outputs a pulse signal corresponding to rotation of a drive shaft of the wheel, and a conversion means, which outputs a voltage corresponding to a frequency of the pulse signal of the rotation detection means.

9. The working vehicle with the HST as set forth in claim 2, further comprising a warning means which warns when vehicle speed is not detected by the vehicle speed detection means.

10. The working vehicle with the HST as set forth in claim 3, further comprising a warning means which warns when vehicle speed is not detected by the vehicle speed detection means.

6. (canceled)