Steerable Transaxle With Hydrostatic Pump And Motor
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Solution Overview
Problem
Conventional hydrostatic transmissions for vehicles, such as garden tractors, face limitations in maneuverability and tire gentleness due to their design, which affects efficiency and surface interaction during operation.
Innovation Solution
A hydrostatic transmission system with a central section containing a single hydraulic pump and two motors, integrated with a steering mechanism and power take-off (PTO) mechanism, optimized for reduced turning radius and gentler wheel pivoting, enhancing maneuverability and reducing tire and surface stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a conventional hydrostatic transmission design is used, then the structure is simpler, but the vehicle turning radius is larger and maneuverability is reduced
Solution Approach 1:
The patent applies dimensionality change by transitioning from a conventional longitudinal pump-motor arrangement to a transverse (side-by-side) motor configuration. The two hydraulic motors are positioned adjacent to each other in the transverse direction, with their drive shafts extending in the longitudinal direction. This spatial reconfiguration reduces the vehicle turning radius and improves maneuverability while maintaining structural integrity.
2Object-affected harmful factors
If a conventional wheel pivoting geometry is used, then the design is simpler, but the tires and surfaces experience greater stress and damage
Solution Approach 1:
The patent applies local quality by implementing asymmetric wheel pivoting geometry where each wheel can pivot independently with optimized angles. The wheel hubs are configured to pivot about vertical axes at specific angles that reduce lateral stress on tires and ground surfaces. This localized optimization at the wheel level reduces harmful effects on tires and surfaces while maintaining overall system simplicity.
3Productivity
If the hydraulic pump and motors are arranged in a conventional configuration, then manufacturing is easier, but the vehicle turning radius is increased
Solution Approach 1:
The patent applies asymmetry by positioning the two hydraulic motors in a non-symmetric transverse arrangement relative to the pump. The motors are located at different lateral positions and orientations, with their drive shafts angled to optimize turning performance. This asymmetric configuration reduces the vehicle turning radius and improves productivity during maneuvering tasks, while the components remain standard hydraulic elements that can be manufactured using conventional processes.
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
The solution improves vehicle maneuverability by reducing the turning radius and gentler tire and surface interaction, thereby increasing efficiency and reducing task completion time while maintaining stability.
Implementation Method 1
a system of one or more hydraulic pumps transmits energy from an input shaft to one or more hydraulic motors connected to one or more output shafts. The hydraulic pumps and motors are contained within a transmission housing filled with hydraulic fluid, which flows in a fluid circuit from pump to motor and back again
Implementation Method 2
The hydraulic pumps and motors are contained within a transmission housing filled with hydraulic fluid, which flows in a fluid circuit from pump to motor and back again through hydraulic porting formed in a center section. It is this flow of hydraulic fluid that transmits energy from the pump(s) to the motor(s). Direction of vehicle travel depends on the direction of flow within the hydraulic circuit.
Data Source
AI summary
A hydrostatic drive includes a transmission having a pump and motor disposed on a center section, and a charge pump to provide fluid to a charge gallery. A power take off (PTO) driven by a prime mover includes a clutch assembly, solenoid valve, and PTO drive member driven by a prime mover input. When the solenoid valve is in a first position, fluid flows from the charge gallery to the clutch to connect the input with the PTO drive member, and when the solenoid valve is in a second position, fluid flows from the PTO mechanism to the sump to disengage the PTO drive member from the input. A filter may be disposed on a land on the center section and seated in a filter pocket in the housing. The filter engages with a bottom surface of the filter pocket to maintain a seal against the land.