Hydrostatic Drive Pump Integration for Speed and Efficiency
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Solution Overview
Problem
Mobile work machines with hydrostatic drives face inefficiencies at high speeds due to increased power loss in drive pumps, limiting maximum driving speed and increasing costs, as existing solutions like additional mechanical transmissions or larger displacement volumes lead to higher power loss and reduced efficiency.
Innovation Solution
A control valve device is introduced to integrate the working hydraulic pump into the closed circuit of the hydrostatic drive, allowing the delivery volume flow to be fed into the high-pressure side of the drive, thereby supporting the traction motor and reducing the displacement volume required from the drive pump, while also allowing the working hydraulic pump to operate in open circuit at low speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the displacement volume of the drive pump is increased to achieve higher driving speeds, then the maximum driving speed is improved, but the power loss of the drive pump increases disproportionately
Solution Approach 1:
The patent merges the working hydraulic pump into the closed circuit of the hydrostatic drive, allowing the working pump to supply pressure medium to the drive motor. This combination enables the working pump to support the drive pump, reducing the required displacement volume of the drive pump while achieving higher driving speeds without disproportionate power loss increase
Solution Approach 2:
The working hydraulic pump is designed to serve dual functions: supplying pressure medium to working consumers and supporting the drive motor in the closed circuit. This multi-functionality allows the system to achieve higher speeds without increasing drive pump displacement volume, thereby avoiding excessive power loss
2Speed
If additional mechanical transmissions are added to achieve increased driving speeds, then the driving speed is improved, but the device complexity and costs increase
Solution Approach 1:
The working hydraulic pump is designed to serve dual functions: supplying pressure medium to working consumers and supporting the drive motor in the closed circuit. This multi-functionality allows the system to achieve higher speeds without adding mechanical transmissions, thereby avoiding increased device complexity and construction effort
3Speed
If the displacement volume of the drive pump is increased to achieve higher driving speeds, then the maximum driving speed is improved, but the efficiency of the drive is reduced
Solution Approach 1:
The patent merges the working hydraulic pump into the closed circuit of the hydrostatic drive, allowing the working pump to supply pressure medium to the drive motor. This combination enables the working pump to support the drive pump, reducing the required displacement volume of the drive pump while achieving higher driving speeds without disproportionate power loss increase
Solution Approach 2:
The system dynamically changes the operational parameters by switching between open circuit operation at low speeds and closed circuit integration at high speeds. This parameter change allows the drive pump to operate at optimal displacement volume across different speed ranges, maintaining drive efficiency while achieving higher maximum speeds
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enables increased driving speeds with reduced power loss and construction effort, improving efficiency and reducing costs by utilizing the working hydraulic pump to support the traction motor at higher speeds, while maintaining the same achievable driving speed with a smaller drive pump displacement volume.
Implementation Method 1
the delivery line (32) of the working hydraulic pump (25) can be connected to the high-pressure-side pressure medium line (6a, 6b) of the hydrostatic travel drive (2), so that the delivery volume flow of the working hydraulic pump (25) can be fed into the high-pressure-side pressure medium line (6a, 6b) of the hydrostatic travel drive (2)
Implementation Method 2
a shut-off valve, in particular a non-return valve, is arranged in the line of the working hydraulic pump, blocking in the direction of the container
Implementation Method 3
the hydrostatic drive (2) having a drive pump (3) driven by a drive motor (4)
Data Source
Figure 1
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Figure 3
AI summary
The invention relates to a mobile working machine with a hydrostatic drive (2) and a working hydraulic pump (25), wherein the hydrostatic drive (2) comprises a drive pump (3) driven by a drive motor (4), in particular an internal combustion engine, of the working machine and at least one drive motor (5) connected to the drive pump (3) in a closed circuit, wherein the closed circuit comprises a first pressure medium line (6a) and a second pressure medium line (6b), and wherein the working hydraulic pump (25) is driven by the drive motor (4) and is designed as a pump operated in an open circuit, which draws pressure medium from a container (11) by means of a suction line (31) and delivers the pressure medium into a delivery line (32) to supply at least one consumer (33) of a working hydraulic system (34) of the working machine with pressure medium.The connection of the delivery line (32) and the suction line (31) of the working hydraulic pump (25) with the pressure medium lines (6a, 6b) of the closed circuit can be controlled by means of a control valve device (60).The control valve assembly (60) has at least one connection position (60b; 60c) in which the delivery line (32) of the working hydraulic pump (25) can be connected to the high-pressure side pressure medium line (6a; 6b) of the hydrostatic drive (2) and the suction line (31) of the working hydraulic pump (25) can be connected to the low-pressure side pressure medium line (6b; 6a) of the hydrostatic drive (2), wherein a shut-off valve (61), in particular a check valve, which closes in the direction of the reservoir (11), is arranged in the suction line (31) of the working hydraulic pump (25) and the return of the volume flow from the low-pressure side pressure medium line (6b; 6a) of the hydrostatic drive (2) to the suction line (31) takes place between the shut-off valve (61) and a suction side (S) of the working hydraulic pump (25).