Axial Piston Pump Control Valve Without Stepped Bores
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Solution Overview
Problem
The manufacturing effort for control pressure valves in hydrostatic axial piston machines is complex due to the need for stepped bores and reamers, especially when multiple valves are used in a common housing, and the adjustment of area ratios is intricate.
Innovation Solution
The actuating pressure valve features a longitudinally displaceable control slide with a longitudinal bore and a cylindrical support body, eliminating the need for stepped bores and allowing easy adjustment of the control pressure range by changing the bore diameter and support body diameter, reducing manufacturing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a stepped bore and stepped piston design is used in the control pressure valve, then sufficient actuating volume and desired dynamics are achieved, but manufacturing effort and complexity increase significantly
Solution Approach 1:
The invention changes the geometric parameters of the control pressure valve by replacing the stepped bore and stepped piston design with a simple cylindrical bore and a piston having two different piston surface areas. This parameter change maintains the functional requirements for actuating volume and dynamics while significantly simplifying the manufacturing process, as cylindrical bores are easier to machine than stepped bores with precise surface finishes
Solution Approach 2:
The invention segments the piston into two distinct surfaces with different areas, rather than creating complexity in the bore structure. The first piston surface area and second piston surface area are differentiated on the same piston body, allowing the bore to remain simple and cylindrical while still achieving the required differential pressure effects for proper valve operation
2Volume of moving object
If multiple control pressure valves are arranged in a common housing bore, then space is optimized, but machining effort increases due to need for multiple reamers
Solution Approach 1:
The invention makes the housing bore universal by designing it with a constant diameter that can accommodate multiple control pressure valves. Each valve uses a piston with differently sized piston surfaces, but all valves share the same simple cylindrical bore geometry, eliminating the need for multiple specialized reamers and simplifying the manufacturing of multi-valve assemblies
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 design significantly reduces manufacturing effort and cost by allowing the housing bore to be machined with a single reamer, simplifying production and component assembly, while maintaining control precision.
Implementation Method 1
the actuating pressure valve is acted upon in the direction of a first control position connecting the first port with the second port and is acted upon by the actuating pressure present in the actuating pressure line in the direction of a second control position connecting the second port with the third port
Implementation Method 2
the actuating pressure valve is controlled by a control device, for example a solenoid
Data Source
Figure 1
Figure 2
AI summary
Hydrostatic axial piston machine (1), in particular an axial piston pump, with adjustable displacement volume, wherein the displacement volume is adjustable by means of a control piston device (5) which has at least one control pressure chamber (5a; 5b). A control pressure valve (10a; 10b) is provided which generates a control pressure acting on the control pressure chamber (5a; 5b). The control pressure valve (10a; 10b) is actuated by a control device (20a; 20b) in the direction of a first control position connecting a first port (A1) with a second port (A2) and is actuated by the control pressure present in a control pressure line (15a; 15b) in the direction of a second control position connecting the second port (A2) with a third port (A3).The actuating pressure valve (10a; 10b) has a control spool (32a; 32b) arranged longitudinally displaceably in a housing bore (30) of a valve housing (31), which is provided with a longitudinal bore (50a; 50b) extending in the control spool (32a; 32b) from an end face (51a; 51b) of the control spool (32a; 32b) to a bore base (52a; 52b). A cylindrical support body (55) is arranged longitudinally displaceably in the longitudinal bore (50a; 50b), and the bore base (52a; 52b) is designed as a control surface actuated by the actuating pressure.