Hydraulic transmission device allowing relatively quiet coupling

Patent metadata

Field	Value
Publication number	US-9896935-B2
Application number	US-201113641489-A
Country	US
Kind code	B2
Filing date	Apr 5, 2011
Priority date	Apr 16, 2010
Publication date	Feb 20, 2018
Grant date	Feb 20, 2018

Abstract

A hydraulic transmission apparatus having at least one declutchable hydraulic motor having radial pistons and connected via two motor ducts, and a casing duct connected to the inside of the casing. The apparatus further has clutching means that, in order to perform the clutching of the motor, are suitable for bringing a first one of the motor ducts to a “clutching” first pressure that is higher than the pressure in the casing while also making it possible to remove fluid via the casing duct. Disposed on the casing duct, the apparatus further has means for limiting the flow of fluid in said casing duct, in a manner such as to cause the pressure inside the casing to increase during the clutching operation. This apparatus enables clutching to take place gently.

First claim

The invention claimed is:

1. Hydraulic transmission apparatus comprising at least one hydraulic motor having radial pistons, said motor comprising:
a casing;
inside the casing, a cylinder block that comprises a plurality of cylinders each cylinder containing a slidably mounted piston and being disposed radially relative to an axis of rotation of the motor; and
an undulating cam for the pistons;
the apparatus further comprising:
two motor ducts respectively for a fluid feed and for a fluid discharge of the motor, said motor ducts being suitable for being put into communication with said cylinders; and
a casing duct connected to an internal space provided inside the casing and in which a casing pressure prevails;
the motor being suitable for being clutched, in which state the pistons slide in the cylinders while being held in contact with the cam, and the motor is suitable for generating outlet torque under the effect of a difference in pressure between the motor ducts, and for being declutched, in which state the pistons are held in retracted position inside the cylinders;
the apparatus comprising, disposed on the casing duct, a limiting valve or a restrictor configured to limit the flow of fluid in said casing duct so as to cause an increase in pressure in the casing duct while fluid flows out of the internal space of the motor via the casing duct during clutching;
and wherein none of the two motor ducts is connected with said limiting valve or restrictor.

2. Apparatus according to claim 1 , further comprising a pressure limiter disposed on the casing duct and suitable for limiting the increase in pressure in the casing.

3. Apparatus according to claim 1 , further comprising a pressure-limiting check valve, mounted in parallel with said limiting valve or restrictor disposed between the casing duct and an auxiliary source of pressurized fluid, and allowing fluid to flow only in the direction going from the casing towards said source.

4. Apparatus according to claim 1 , wherein the apparatus is configured to maintain the second motor duct at a second pressure less than the clutching pressure during the clutching operation, and said limiting valve or restrictor disposed on the casing duct is dimensioned in such a manner that, during a major fraction of the clutching operation, the casing pressure remains between the first pressure and the second pressure.

5. Apparatus according to claim 1 , wherein, in parallel with said limiting valve or restrictor disposed on the casing duct, the apparatus is configured, during the clutching operation, to connect the casing duct via a rated valve to the second motor duct, in order to limit the pressure in the casing.

6. Apparatus according to claim 1 , further comprising a main pump, and wherein:
the apparatus is configured to put a main delivery orifice of the main pump into communication with the first motor duct during the clutching operation, so as to make it possible to feed the motor;
the motor is connected to at least one wheel so as to drive it; and
the apparatus is configured, before the clutching operation is performed, to synchronize the main pump by causing the cylinder capacity of said pump to vary until it reaches a value making it possible to drive the motor at a speed of rotation different by less than 25% from a speed of the wheel.

7. Apparatus according to claim 1 , further comprising a main pump and an auxiliary pump, and wherein the apparatus is configured to connect a delivery orifice of the auxiliary pump to the first motor duct during the clutching operation.

8. Apparatus according to claim 1 , wherein the apparatus is configured, during the clutching operation, to connect the casing duct to the second motor duct.

9. Apparatus according to claim 1 , wherein, in parallel with said limiting valve or restrictor disposed on the casing duct, the apparatus is configured to connect the casing duct to a fluid supply duct via a check valve for filling the casing, making it possible to supply fluid to the casing during the operation of declutching the motor.

10. Apparatus according to claim 9 , wherein the apparatus is configured, during the operation of declutching the motor, to connect the accumulator to the casing duct on the same side of the first constriction as the casing and/or the check valve for filling the casing.

11. Apparatus according to claim 1 , further comprising an accumulator suitable for feeding the casing duct for putting this duct under pressure during an operation of declutching the motor, thereby making it easier for the pistons to retract into the cylinders.

12. Apparatus according to claim 11 , wherein the said limiting valve or restrictor disposed on the casing duct comprises a first constriction, and wherein said first constriction is disposed on the casing duct between the casing and the accumulator, and, during the operation of clutching the motor, the fluid removed from the casing can be directed towards the accumulator via the first constriction only.

13. Apparatus according to claim 11 , wherein the apparatus is configured, during the operation of declutching the motor, to connect the accumulator to the casing duct on the same side of the first constriction as the casing and/or the check valve for filling the casing.

14. Apparatus according to claim 1 , wherein the apparatus is configured, during the operation of declutching the motor, to connect a accumulator to the casing duct on the same side of a first constriction as the casing and/or the check valve for filling the casing.

15. Apparatus according to claim 11 , wherein, in order to declutch the motor, the apparatus is configured, in a first step, to connect the motor ducts to the casing duct, and, in a second step, to connect the accumulator to the casing duct.

16. Apparatus according to claim 15 , wherein, in order to declutch the motor, the apparatus is configured to connect the motor ducts firstly to an unpressurized reservoir via a removal line including a constriction, and secondly to the casing duct via a fluid recovery link including a check valve, the fluid recovery link connecting to the removal line between the motor(s) and said constriction, and the check valve allowing the fluid to pass through only towards the casing duct, whereby the increase in pressure in the removal line caused by said constriction during the declutching operation causes fluid to be injected into the casing.

17. Apparatus according to claim 1 , wherein said limiting valve or restrictor disposed on the casing duct is a valve.

18. Apparatus according to claim 1 , wherein said limiting valve or restrictor disposed on the casing duct is a restrictor.

19. Apparatus according to claim 1 , configured so that, when the pistons extend, since fluid removal from the casing is limited by the limiting valve or restrictor disposed on the casing duct, the pressure inside the casing increases, thus forming a back pressure having an effect opposing the effect of the pressure in the cylinders; and once the clutching is performed, the back pressure falls spontaneously without requiring any action to be taken.

20. Hydraulic transmission apparatus comprising at least one hydraulic motor having radial pistons, said motor comprising:
a casing;
inside the casing, a cylinder block that comprises a plurality of cylinders each cylinder containing a slidably mounted piston and being disposed radially relative to an axis of rotation of the motor; and
an undulating cam for the pistons;
the apparatus further comprising:
two m

Assignees

• Prigent Andre
• Lambey Julien
• Poclain Hydraulics Ind

Inventors

• Prigent Andre
• Lambey Julien

Classifications

• F03C1/047

  the pistons co-operating with an actuated element at the outer ends of the cylinders · CPC title

• B60K17/356 Primary

  having fluid or electric motor, for driving one or more wheels · CPC title

• F03C1/0478

  having several cylinder barrels coupled together · CPC title

• F01C21/008 Primary

  Driving elements, brakes, couplings, transmissions specially adapted for rotary or oscillating-piston machines or engines (brakes, couplings, transmissions per se F16, B60) · CPC title

• F16H61/4183

  Preventing or reducing vibrations or noise, e.g. avoiding cavitations · CPC title