Full-hydraulic steering gear integrated with priority valve and casting mold loose core

Abstract

The invention relates to a full-hydraulic steering gear integrated with a priority valve and a casting mold loose core, and belongs to the technical field of hydraulic transmission. An integrated valve body is provided with a penetrating priority valve hole and a full-hydraulic steering gear hole with parallel axes; the priority valve hole is provided with an EF groove, a p groove and a CF groove which are axially distributed at intervals and are respectively communicated with the working oil port, the oil inlet and the steering port on the integrated valve body; the full-hydraulic steering gear hole is provided with a T groove, an A groove, a B groove and a P groove, wherein the T groove, the A groove and the B groove are axially distributed at intervals and communicated with an upper oil return opening, a left execution opening and a right execution opening of the integrated valve body respectively. A main one-way valve hole is formed between the priority valve hole and the full-hydraulic steering gear hole in a penetrating manner; the bottom of the small hole section of the main one-way valve hole communicates with a CF groove of the priority valve hole through a first casting hole, and the bottom of the large hole section of the main one-way valve hole communicates with a P groove of the full-hydraulic steering gear hole through a second casting hole. The structure is very compact, the occupied space is small, the installation requirements under narrow and complex working conditions can be met, and energy conservation and efficiency improvement are facilitated.

Description

Technical Field

[0001] This invention relates to a fully hydraulic steering gear, particularly a fully hydraulic steering gear with an integrated priority valve, and also to a corresponding mold core pulling method, belonging to the field of hydraulic transmission and control technology. Background Technology

[0002] The traditional priority valve and steering gear combined with a fully hydraulic steering system can not only prioritize the flow to the steering oil circuit according to its requirements, ensuring sufficient oil supply regardless of changes in load pressure or steering wheel speed, thus guaranteeing smooth and reliable steering; but also, in addition to allocating the flow necessary to maintain normal operation of the steering oil circuit, the remaining flow output by the oil pump can be supplied to the auxiliary oil circuit, thereby eliminating power loss caused by excessive oil supply to the steering oil circuit.

[0003] However, for a long time, existing full hydraulic steering systems have required the additional installation of priority valves (such as the "Two-way Buffer Load Sensing Large Flow Amplification Full Hydraulic Steering Gear" disclosed in CN200620098121), which not only increases the number of oil leakage points, but also requires a large installation space and is inconvenient for pipeline connection.

[0004] The patent document with application number 201520215571.7 discloses an improved priority valve that is directly fixedly connected to the steering gear. It includes a valve body and a valve stem that cooperates with the valve body. The valve stem is assembled in the valve hole of the valve body by a spring and a plug. The key feature is that the valve body is fixedly connected to the threaded hole of the steering gear through a connecting hole. The priority valve port LS on the valve body and the steering gear port LS are directly connected, as are the priority valve port CF on the valve body and the steering gear port P. The advantages are that the priority valve's CF and LS ports are directly connected to the steering gear's inlet ports P and LS, eliminating the need for piping connections, reducing system pressure loss, and making the LS signal transmission between the steering gear and the priority valve direct, rapid, and sensitive, thus improving the steering gear's operability and reliability. However, because the priority valve and the steering gear valve body are manufactured separately, each requiring sufficient wall thickness and bolt fastening, the structure is still not compact enough. It involves many assembly and sealing steps and is not small enough, making it difficult to meet the needs of convenient installation in confined assembly spaces. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of the existing technology by proposing a fully hydraulic steering gear with an integrated priority valve that has a very compact structure through bold innovation in structure and process, thereby meeting the need for convenient installation in confined assembly spaces with a small, independent valve body.

[0006] After comparing various layout schemes, it was determined that installing a priority valve and a fully hydraulic steering gear with parallel axes on the same valve body resulted in the most compact structure. The bottleneck problem for this scheme is how to set up the main check valve connecting the priority valve and the fully hydraulic steering gear, especially how to form the required internal connecting hole, while maintaining a compact structure and ensuring technological feasibility. The traditional approach to placing the main check valve parallel between the priority valve and the fully hydraulic steering gear involves drilling a hole in the valve body and then plugging the hole to form the internal connecting hole. This is not only complex but also increases the risk of oil leakage. Therefore, to date, no fully hydraulic steering gear with an integrated priority valve on a single valve body has been found.

[0007] Through brainstorming and continuous coordination in both structural and process design, a feasible basic technical solution for a fully hydraulic steering gear with an integrated priority valve was finally determined: It includes an integrated valve body, which is equipped with a through priority valve port and a fully hydraulic steering gear port with parallel axes, for housing priority valve and fully hydraulic steering gear components, respectively. The priority valve orifice has axially spaced EF grooves, p grooves, and CF grooves that are respectively connected to the working oil port (EF port), oil inlet port (P port), and turning port (CF port) on the integrated valve body. The fully hydraulic steering gear bore has axially spaced T-grooves, A-grooves, and B-grooves that are respectively connected to the upper oil return port (T-port), left actuation port (A-port), and right actuation port (B-port) of the integrated valve body, as well as a P-groove that is indirectly connected to the oil inlet of the integrated valve body. Between the priority valve hole and the full hydraulic steering gear hole of the integrated valve body, a main one-way valve hole with a shoulder shape, smaller inside and larger outside, is formed from one end; the bottom of the small hole section of the main one-way valve hole is connected to the CF groove of the priority valve hole through the first casting hole, and the bottom of the large hole section is connected to the P groove of the full hydraulic steering gear hole through the second casting hole.

[0008] Thus, as long as the problem of casting the mold core is solved, the priority valve, the main check valve, and the bottom hole of the full hydraulic steering gear can be cast at the same time during the valve body casting process, and the first and second connecting holes can also be cast simultaneously. Then, the bottom holes can be machined as needed to install the priority valve hole, the main check valve, and the components of the full hydraulic steering gear, forming the full hydraulic steering gear with integrated priority valve of the present invention.

[0009] The integrated valve body mold core pulling of the fully hydraulic steering gear with integrated priority valve of the present invention includes two end supports, and there are priority valve core holes and fully hydraulic steering gear core holes with parallel axes between the two end supports, which are respectively used to cast to form priority valve base holes and fully hydraulic steering gear base holes; The priority valve core has EF grooves, p grooves, and CF grooves that are axially spaced apart. The fully hydraulic steering gear core has T-grooves, A-grooves, B-grooves, and P-grooves that are axially spaced. Between the priority valve core and the full hydraulic steering gear core, a main one-way valve core with a shoulder-shaped structure extending from one end is supported; the bottom of the small hole section of the main one-way valve core is connected to the EF groove of the priority valve core through a first cast core, and the bottom of the large hole section is connected to the P groove of the full hydraulic steering gear core through a second cast core.

[0010] The casting process using a mold core involves the following steps: 1) Core pulling – used to form internal cavities or corresponding cavities for solid parts of castings in sand molds; 2) Sand mold preparation - Sand molds containing a gating system (internal flow channel) are made using coated sand. The surface is coated with a coating to improve the strength of the sand mold and reduce the surface roughness of the casting to prevent porosity. 3) Casting – The sand mold is placed in the casting box, the sand is poured, and the casting is formed after cooling; 4) Demolding and sand removal – After casting, the molding sand on the surface of the casting is removed by roller vibration or sandblasting. The molding sand in the internal flow channels of the casting is removed by shot peening. Then, machining can be performed.

[0011] The integrated priority valve full hydraulic steering gear of the present invention directly integrates the priority valve into the hydraulic steering gear, reducing the number of independent valve bodies in the system. The structure is very compact, occupies little space, and is very convenient to install, which can meet the installation requirements in narrow and complex working conditions. At the same time, due to the short internal oil circuit, it is conducive to energy saving and efficiency. In addition, the main check valve and the casting hole structure on both sides are conducive to forming a stable mold core, which facilitates sand removal after casting. Therefore, it is very ingenious and reasonable. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of a structure according to an embodiment of the present invention.

[0013] Figure 2 yes Figure 1 A cross-sectional view of the priority valve core in the embodiment.

[0014] Figure 3 yes Figure 1 A schematic diagram of the integrated valve body casting core-pulling structure used in the embodiment.

[0015] Figure 4 yes Figure 1 A schematic diagram of the three-dimensional structure of the integrated valve body in the embodiment.

[0016] Figure 5 yes Figure 1 A cross-sectional view of the valve sleeve of the fully hydraulic steering gear in the embodiment.

[0017] Figure 6 yes Figure 1 Side view.

[0018] Figure 7 yes Figure 6 A schematic diagram of a partial cross-sectional view of BB.

[0019] Figure 8 yes Figure 1 Schematic diagram of the hydraulic system in the embodiment. Detailed Implementation

[0020] Example 1 The basic structure of the fully hydraulic steering gear with integrated priority valve in this embodiment is as follows: Figure 1 As shown, the integrally cast integrated valve body 1 has a through priority valve hole and a full hydraulic steering gear hole with parallel axes, which are used to house the components of the priority valve 2 and the full hydraulic steering gear 3, respectively. A main check valve hole with a small inner and large outer shoulder shape is made from one end between the through priority valve hole and the full hydraulic steering gear hole, in which the main check valve 4 is housed.

[0021] Specifically, a priority valve core 2.1, forming a sliding pair, is installed in a priority valve bore with axially spaced grooves EF-1, p-2, and CF-3 that communicate with the working port (EF port), inlet port (P port), and steering port (CF port) on the integrated valve body 1, respectively. A limit cap 2.2 and a spring cap 2.3 are threaded onto both ends. A silencing groove 2-4 is added between EF-1 and p-2-2 to reduce hydraulic shock and noise, while also helping to reduce hydraulic force and hydraulic losses. A valve core spring 2.4, with one end abutting against the valve core spring end hole of the priority valve core 2.1, is installed in the center hole. The priority valve core 2.1 is as follows: Figure 2 As shown, there is a throttling orifice 2.22 (PP port) with a diameter of 1.1 mm between the valve core spring end hole 2.21 and the central core hole 2.24. The other end is fitted with a throttling plug 2.5 through a threaded inner hole 2.25 with an flared end. This throttling plug 2.5 has a throttling orifice (Ls port) with a diameter of 0.8 mm leading to the return port on the integrated valve body. Figure 1 ).

[0022] Through the optimized design of the throttling orifices 2.22 and throttling holes at both ends of the priority valve core 2.1, the precise axial movement of the priority valve core shaft can be controlled, thereby enabling the priority valve to accurately supply oil to the steering gear and effectively avoiding flow instability and hydraulic line vibration caused by priority valve core vibration. During operation, the oil from the CF port enters the core hole 2.24 of the priority valve core through the throttling orifice 2.22 (PP port) and the throttling hole (Ls port) of the throttling plug 2.5, and together with the valve core spring 2.4, forms a pressure difference that matches the steering working pressure, thus achieving the required oil supply (i.e., "the required flow rate comes only as needed"). The internal control pressure of the valve core spring is 0.4MPa, ensuring that the flow rate supplied to the steering gear is always only 0.4MPa greater than the working pressure, thereby effectively saving energy.

[0023] The fully hydraulic steering gear has axially spaced grooves 3-1, 3-2, 3-3, and 3-4 that communicate with the upper return port (T port), left actuation port (A port), right actuation port (B port), and inlet port (P port) of the valve body, respectively. The steering flow distribution switching mechanism, mainly composed of valve sleeve 3.1 and valve core 3.2, cycloidal pinwheel pair 3.3, and linkage shaft 3.5 connecting the steering flow distribution switching mechanism and cycloidal pinwheel pair through pin 3.4 and spline pair are installed, thus forming a fully hydraulic steering gear. These are the same as those in the prior art and will not be described in detail.

[0024] The bottom of the small hole section 4-1 of the main check valve hole is connected to the CF groove 2-3 of the priority valve hole through the first casting hole 4-3, and the bottom of its large hole section 4-2 is connected to the P groove of the full hydraulic steering gear hole through the second casting hole 4-4 with an outward-curving section.

[0025] The corresponding integrated valve body casting core pulling in this embodiment is as follows: Figure 3 As shown, it includes a priority valve core 2' and a full hydraulic steering gear core 3' with parallel axes between the two end supports 1' and 1', which are used to cast the priority valve base hole and the full hydraulic steering gear base hole, respectively.

[0026] The priority valve core 2' has axially spaced EF groove 2-1', p groove 2-2', and CF groove 2-3'; a silencing groove 2-4' is also added between EF groove 2-1' and p groove 2-2'. The full hydraulic steering gear core 3' has axially spaced T groove 3-1', A groove 3-2', B groove 3-3', and P groove 3-4'.

[0027] Between the priority valve core 2' and the full hydraulic steering core 3', a main check valve core 4' with a shoulder-shaped structure, smaller inside and larger outside, extends from one end of the support 1". The bottom of the small hole section 4-2' of the main check valve core 4' is connected to the EF groove core 2-3' of the priority valve core 4' through the first cast core 4-3', and the bottom of the large hole section 4-4' is connected to the P groove core 3-4' of the full hydraulic steering core through the second cast core 4-1' with an outwardly inclined section.

[0028] Compared with the prior art, the fully hydraulic steering gear with integrated priority valve in this embodiment also has the following structural features: like Figure 1 As shown, the extended shaft of valve core 3.2 has an extended internal spline that can be directly connected to the steering wheel, thus eliminating the need for the original steering column, simplifying the structure and making the connection more convenient.

[0029] like Figure 4 As shown, the P port, A port, and B port of the integrated valve body 1 are located on three protrusions on the same plane on the outer end face, which facilitates installation and connection.

[0030] like Figure 5 As shown, the basic structure of the valve sleeve 3.1 is the same as that of the prior art. The difference is that an annular groove-shaped pressure equalization groove 3.11 is made at the oil hole of the T groove 3-1 on the valve body 1. This allows the pressure oil on the circumference to communicate with each other, suppresses the jamming phenomenon between the valve core and the valve hole, ensures that the valve sleeve is evenly stressed in the circumferential direction, rotates flexibly, and avoids jamming due to hydraulic force.

[0031] like Figure 7 (combined) Figure 6 , Figure 8 As shown in the diagram, the steering gear oil circuit of the integrated valve body 1 connects to the throttle orifice (Ls port) of the priority valve via an integrated damping check valve 7 and an overflow oil circuit, allowing oil to flow only to the priority valve and providing a pressure signal to control the position of the priority valve. The overflow circuit connects to the return port (T port) via an overflow valve 7'. The cylindrical valve body 7.2 of the damping check valve 7 has a valve ball built into its central hole, and the oil inlet end has a damping hole 7.1 with a diameter of 1.1 mm communicating with the central hole. The oil outlet end has a riveted notch 7.3 to prevent the valve ball from falling out. When the hydraulic cylinder oil pressure suddenly increases when the steering reaches the end point, the overflow check valve allows high-pressure oil to slowly permeate through the check valve and through the inclined hole 1.7 on the integrated valve body to the Ls port. When the accumulated pressure reaches the opening threshold of the overflow valve, the overflow valve opens from the Ls port, allowing excess high-pressure oil to return through the overflow valve. This avoids a continuous surge in system pressure and prevents the hydraulic pump from continuously outputting high-pressure oil, thereby achieving energy saving.

[0032] The working principle of this embodiment is based on the hydraulic system principle familiar to those skilled in the art. Figure 8 The basic working principle remains the same: hydraulic fluid flows through the CF port of the priority valve 2, the main check valve 4, and then to the inlet of the steering gear 3, thus enabling the priority valve to control the flow of hydraulic fluid into the steering gear. Details are omitted here. Its key feature is the breakthrough from the long-standing modular steering gear design, innovating with an integrated valve body. This transforms the traditional external priority valve block into an integrated design, resulting in a simpler structure and better adaptability. Furthermore, the main check valve 4 prevents hydraulic backflow and stabilizes pressure, preventing steering wheel jerking, vibration, or rebound. The throttle orifice (Ls port) leading to the integrated valve body's return port (T port) forms a neutral return oil circuit, allowing pressure relief to return to the T port. This ensures that hydraulic fluid enters the steering gear when it is in the neutral position, providing insulation and preparing it for the next steering maneuver.

[0033] Experiments show that, compared with the prior art, this embodiment has the following beneficial effects: 1. The unique integrated valve body design reduces the number of independent valves in the system, resulting in a more compact structure, smaller footprint, strong adaptability, and quick installation, meeting the assembly needs of various complex working conditions.

[0034] 2. The design of the valve core shaft head can increase the installation position of bearings and other supporting components, achieving more stable positioning and support. At the same time, it effectively improves the positioning of the extended valve core, as well as the convenience of external connection, and also improves the comfort of steering.

[0035] 3. Reducing the diameter of the deflector pin increases the rotation angle of the valve core sleeve, thereby increasing the oil passage area, reducing steering resistance, and improving steering sensitivity.

[0036] 4. The integrated overflow check valve is easy to install and disassemble, while the damping orifice improves system stability and saves energy.

[0037] In summary, given the market's increasing demands for precise control of agricultural machinery, the integrated priority valve full hydraulic steering system of this embodiment not only provides stable and reliable steering control for high-precision operation of tractors, harvesters, and other machinery in the field, but also allows for flexible adjustment of hydraulic oil distribution based on the vehicle's steering requirements and the load of the working system, ensuring steering sensitivity and efficient operation of the working system and meeting diverse operational needs. Moreover, its compact structure effectively solves the problem of convenient installation in confined assembly spaces.

[0038] In addition to the embodiments described above, the present invention may have other implementations. All technical solutions formed by equivalent substitution or equivalent transformation fall within the protection scope claimed by the present invention.

Claims

1. A fully hydraulic steering gear with an integrated priority valve, characterized in that: It includes an integrated valve body, which is equipped with a through priority valve port and a fully hydraulic steering gear port with parallel axes, for housing priority valve and fully hydraulic steering gear components, respectively. The priority valve orifice has axially spaced EF grooves, p grooves, and CF grooves that are respectively connected to the working oil port (EF port), oil inlet port (P port), and turning port (CF port) on the integrated valve body. The fully hydraulic steering gear bore has axially spaced T-grooves, A-grooves, and B-grooves that are respectively connected to the upper oil return port (T-port), left actuation port (A-port), and right actuation port (B-port) of the integrated valve body, as well as a P-groove that is indirectly connected to the oil inlet of the integrated valve body. Between the priority valve hole and the full hydraulic steering gear hole of the integrated valve body, a main one-way valve hole with a shoulder shape, smaller inside and larger outside, is formed from one end; the bottom of the small hole section of the main one-way valve hole is connected to the CF groove of the priority valve hole through the first casting hole, and the bottom of the large hole section is connected to the P groove of the full hydraulic steering gear hole through the second casting hole.

2. The fully hydraulic steering gear with an integrated priority valve according to claim 1, characterized in that: The priority valve orifice is equipped with a priority valve core (2.1) that forms a moving pair with it, and the two ends are respectively threaded with a limit end cap (2.2) and a spring end cap (2.3).

3. The fully hydraulic steering gear with an integrated priority valve according to claim 2, characterized in that: A sound-absorbing groove (2-4) is provided between the EF groove (2-1) and the p groove (2-2).

4. The fully hydraulic steering gear with an integrated priority valve according to claim 3, characterized in that: The center hole of the spring end cap (2.3) is fitted with a valve core spring (2.4) that abuts against the valve core spring end hole of the priority valve core (2.1).

5. The fully hydraulic steering gear with an integrated priority valve according to claim 2, 3, or 4, characterized in that: The priority valve core has a throttling port (2.22) between the valve core spring end hole (2.21) and the central core hole (2.24), and the other end is fitted with a throttling plug (2.5) through a threaded inner hole (2.25) with an flared end. The throttling plug has a throttling port (Ls port) leading to the return oil port on the integrated valve body.

6. The fully hydraulic steering gear with an integrated priority valve according to claim 5, characterized in that: The bottom of the large hole section (4-2) of the main one-way valve hole is connected to the P groove of the fully hydraulic steering gear hole through the second casting hole (4-4) with an outwardly inclined section.

7. The fully hydraulic steering gear with an integrated priority valve according to claim 6, characterized in that: The valve core (3.2) has an extended internal spline that can be directly connected to the steering wheel.

8. The fully hydraulic steering gear with an integrated priority valve according to claim 7, characterized in that: The P port, A port, and B port of the integrated valve body are located on three protrusions on the same plane on the outer end face; the valve sleeve has an annular groove-shaped pressure equalization groove (3.11) at the oil hole of the T groove on the valve body.

9. The fully hydraulic steering gear with an integrated priority valve according to claim 8, characterized in that: The steering oil circuit of the integrated valve body is connected to the throttle orifice (Ls port) of the priority valve through the overflow oil circuit via the integrated damping check valve (7); the overflow circuit is connected to the return oil port (T port) through the overflow valve (7'); the cylindrical valve body (7.2) of the damping check valve has a valve ball built into the central hole, and its oil inlet end is provided with a damping hole 7.1 communicating with the central hole.

10. A core-pulling tool for manufacturing a fully hydraulic steering gear with an integrated priority valve as described in any one of claims 1 to 9, characterized in that: Includes two-end supports, with a priority valve core and a full hydraulic steering gear core with parallel axes between the two-end supports, which are respectively used to cast the priority valve base hole and the full hydraulic steering gear base hole; The priority valve core has EF grooves, p grooves, and CF grooves that are axially spaced apart. The fully hydraulic steering gear core has T-grooves, A-grooves, B-grooves, and P-grooves that are axially spaced. Between the priority valve core and the full hydraulic steering gear core, a main one-way valve core with a shoulder-shaped structure extending from one end is supported; the bottom of the small hole section of the main one-way valve core is connected to the EF groove of the priority valve core through a first cast core, and the bottom of the large hole section is connected to the P groove of the full hydraulic steering gear core through a second cast core.

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