US-20260126104-A1 - HYDRAULIC SYSTEMS FOR A POWER MACHINE

US20260126104A1US 20260126104 A1US20260126104 A1US 20260126104A1US-20260126104-A1

Abstract

A hydraulic system for a power machine can include a hydrostatic drive motor, a hydrostatic drive pump that is in communication with the hydrostatic drive motor via a hydrostatic drive circuit. A drain case can include one or more of the hydrostatic drive motor or the hydrostatic drive pump. A venturi device can include a main flow inlet in communication with the hydrostatic drive circuit, a main flow outlet, and a suction inlet in communication with the drain case. The hydraulic system can further include a heat exchanger, a tank, and an assist pump that includes an assist pump inlet in communication with the main flow outlet of the venturi device and an assist pump outlet in communication with the heat exchanger.

Inventors

Nicolas Galès
Arnaud Guinee

Assignees

DOOSAN BOBCAT NORTH AMERICA, INC.

Dates

Publication Date: 20260507
Application Date: 20251105

Claims (19)

1 . A hydraulic system for a power machine, the hydraulic system comprising: a hydrostatic drive motor; a hydrostatic drive pump in communication with the hydrostatic drive motor via a hydrostatic drive circuit; a drain case that includes one or more of the hydrostatic drive motor or the hydrostatic drive pump; a venturi device that includes a main flow inlet in communication with the hydrostatic drive circuit, a main flow outlet, and a suction inlet in communication with the drain case, the venturi device being configured to provide suction to the drain case via the suction inlet during flow of fluid from the main flow inlet to the main flow outlet; a heat exchanger; a tank; and an assist pump that includes an assist pump inlet in communication with the main flow outlet of the venturi device and an assist pump outlet in communication with the heat exchanger, the assist pump being configured to receive flow from the main flow outlet of the venturi device and provide pressurized flow to the tank via the heat exchanger.
2 . The hydraulic system of claim 1 , wherein the hydrostatic drive circuit includes a shuttle valve in communication with the main flow inlet of the venturi device.
3 . The hydraulic system of claim 1 , further comprising: a power source with a rotational output; wherein the hydrostatic drive motor and the assist pump are commonly powered by the rotational output.
4 . The hydraulic system of claim 1 , further comprising: one or more additional pumps; wherein an outflow from the one or more of the additional pumps is: in communication with the hydrostatic drive circuit, to provide charge flow to the hydrostatic drive circuit; or in communication with the main flow inlet of the venturi device, to provide supplemental flow through the venturi device.
5 . The hydraulic system of claim 4 , wherein the one or more additional pumps includes an auxiliary pump arranged to power a cooling fan for a power source of the power machine.
6 . The hydraulic system of claim 5 , wherein the one or more additional pumps includes an implement pump arranged to power a hydraulic workgroup actuator of the power machine.
7 . The hydraulic system of claim 1 , further comprising: a primary drainage line that extends between the heat exchanger and the tank; and a recirculation line that extends from the primary drainage line to a location between the assist pump inlet and the main flow outlet of the venturi device.
8 . The hydraulic system of claim 1 , further comprising: an implement pump arranged to power a hydraulic workgroup actuator of the power machine; and a discharge path between the hydraulic workgroup actuator and the tank; wherein the assist pump inlet is in communication with the discharge path to route a portion of flow from the discharge path through the heat exchanger.
9 . A power machine comprising: a power source; a hydrostatic drive system that includes: a hydrostatic drive circuit; a drive pump powered by the power source; a drive motor powered by the drive pump via the hydrostatic drive circuit; and a drain case that includes the drive motor; a venturi device that includes a main flow inlet, a main flow outlet, and a suction inlet in communication with the drain case; a heat exchanger; a tank; and an assist pump that is powered by the power source and includes: an assist pump inlet supplied by the main flow outlet of the venturi device, and an assist pump outlet in communication with the heat exchanger; the hydrostatic drive system being configured to supply flow to the main flow inlet of the venturi device, to draw fluid from the drain case via the suction inlet of the venturi device; and the assist pump being configured to route the fluid drawn from the drain case to the tank, via the heat exchanger.
10 . The power machine of claim 9 , further comprising: an auxiliary pump that is powered by the power source and includes: an auxiliary pump outlet, and an auxiliary pump inlet in communication with the tank; wherein the auxiliary pump outlet is in communication with: the hydrostatic drive circuit, to provide charge flow for operation of the drive pump and the drive motor; and the main flow inlet of the venturi device, to provide supplemental flow for generation of suction at the suction inlet.
11 . The power machine of either of claims 9 or 10 , further comprising: an implement pump that is powered by the power source and that includes an implement pump inlet in communication with the tank and an implement pump outlet; wherein the implement pump outlet is in communication with: the hydrostatic drive circuit, to provide further charge flow for operation of the drive pump and the drive motor; and the main flow inlet of the venturi device, to provide further supplemental flow for generation of suction at the suction inlet.
12 . The power machine of either of claims 9 or 10 , further comprising: an implement pump that is powered by the power source and includes: an implement pump outlet, and an implement pump inlet in communication with the tank; wherein the implement pump outlet is in communication with the tank and is further in communication with the assist pump inlet in parallel with flow from the main flow outlet of the venturi device.
13 . The power machine of claim 9 , wherein the power machine is a telehandler.
14 . A method of operating a power machine, the method comprising: operating a hydrostatic drive pump of the power machine to provide pressurized flow of fluid within a hydrostatic drive circuit; routing a portion of the fluid from the hydrostatic drive circuit to a main flow inlet of a venturi device, to generate suction at a suction inlet of the venturi device and thereby induce fluid from a drain case of the hydrostatic drive circuit to flow from a main flow outlet of the venturi device; and using an assist pump, pressurizing the flow from the main flow outlet of the venturi device to flow through a heat exchanger to tank.
15 . The method of claim 14 , further comprising: operating an auxiliary pump to provide supplemental flow at the main flow inlet of the venturi device.
16 . The method of claim 15 , wherein the supplemental flow from the auxiliary pump powers a cooling fan for a power source of the power machine, upstream of the main flow inlet of the venturi device.
17 . The method of claim 14 , further comprising: operating an implement pump to power an implement of the power machine and provide supplemental flow at the main flow inlet of the venturi device.
18 . The method of claim 14 , further comprising: operating an implement pump to power an implement of the power machine and provide supplemental flow at an inlet to the assist pump, without passing through the venturi device.
19 . The method of claim 14 , wherein the flow from the heat exchanger to the tank flows along a primary drainage line; and wherein operating the assist pump draws additional flow from the primary drainage line to an inlet of the assist pump, via a recirculation line that supplies the assist pump without passing through the venturi device.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. provisional application No. 63/716,297, filed 5 Nov. 2024, which is hereby incorporated by reference in its entirety as though fully set forth herein. BACKGROUND This disclosure is directed toward power machines. More particularly, the present disclosure is directed to a hydraulic system for power machines. Power machines, for the purposes of this disclosure, include any type of machine that generates power to accomplish a particular task or a variety of tasks. One type of power machine is a work vehicle. Work vehicles are generally self-propelled vehicles that have a work device (e.g., a lift arm or an implement) that can be manipulated to perform a work function. Work vehicles include telehandlers, loaders, excavators, utility vehicles, tractors including compact tractors, and trenchers, to name a few examples. Other types of power machines can include mini-loaders (e.g., mini track loaders), and mowers. Different types of power machines, including telehandlers, can include a power system powered by a power source to operate one or more components of the power machine. For example, some power machines include hydraulic systems that are powered by an internal combustion engine to operate tractive elements of the power machine. The discussion above is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter. SUMMARY According to some aspects of the disclosure, a hydraulic system for a power machine can be provided. The hydraulic system can include a hydrostatic drive motor, a hydrostatic drive pump that is in communication with the hydrostatic drive motor via a hydrostatic drive circuit. A drain case can include one or more of the hydrostatic drive motor or the hydrostatic drive pump. A venturi device can include a main flow inlet in communication with the hydrostatic drive circuit, a main flow outlet, and a suction inlet in communication with the drain case. The venturi can operate to provide suction to the drain case via the suction inlet during flow of fluid from the main flow inlet to the main flow outlet. The hydraulic system can further include a heat exchanger, a tank, and an assist pump that includes an assist pump inlet in communication with the main flow outlet of the venturi device and an assist pump outlet in communication with the heat exchanger. The assist pump can operate to receive flow from the main flow outlet of the venturi device and provide pressurized flow to the tank via the heat exchanger. According to some aspects of the disclosure, a power machine can include a power source and a hydraulic drive system that includes a hydrostatic drive circuit, a drive pump powered by the power source, a drive motor powered by the drive pump via the hydrostatic drive circuit, and a drain case that includes the drive motor. The power machine can include a venturi device that includes a main flow inlet, a main flow outlet, and a suction inlet in communication with the drain case. A heat exchanger and a tank can be provided. The power machine can include an assist pump that is powered by the power source and includes an assist pump inlet supplied by the main flow outlet of the venturi device and an assist pump outlet in communication with the heat exchanger. The hydrostatic drive system can supply flow to the main flow inlet of the venturi device, to draw fluid from the drain case via the suction inlet of the venturi device. The assist pump can route the fluid drawn from the drain case to the tank, via the heat exchanger. According to some aspects of the disclosure, a method of operating a power machine can be provided. A hydrostatic drive pump of the power machine can be operated to provide flow of fluid within a hydrostatic drive circuit. A portion of the fluid can be routed from the hydrostatic drive circuit to a main flow inlet of a venturi case, to generate suction at a suction inlet of the venturi device and thereby induce fluid from a drain case of the hydrostatic drive circuit to flow from a main flow outlet of the venturi device. Using an assist pump, the flow from the main flow outlet of the venturi device can be pressurized to flow through a heat exchanger to tank. This Summary and the Abstract are provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor are they intended to be used as an aid in determining the scope of the claimed subject matter. BRIEF DESCRIPTION OF THE DRAWINGS The following drawings are provided to help illustrate various features of non-limiting examples of the present disclosure and are not intended to limit the scope of the disclosure or exclude alternative implementations. FIG. 1 is a block diagram illustrating func