A new type of variable assist hydraulic steering system

Abstract

The present invention relates to a novel variable assist hydraulic steering system, which includes a hydraulic circuit and a steering controller. The hydraulic circuit includes a steering pump, a hydraulic power steering gear, a pressure limiting valve, a steering assist cylinder, a differential and a proportional flow valve. The steering pump is connected to the engine. The proportional flow valve is connected in parallel with the hydraulic power steering gear to form a circuit and then connected to the steering controller, and is controlled by the steering controller. The differential is connected in series with the hydraulic power steering gear to be incorporated into the hydraulic network. In this application, the differential is adopted to ensure that the lightness of vehicle steering is not affected when the displacement of the oil pump is reduced, thereby achieving the purpose of reducing the energy loss of the hydraulic assist steering system and simultaneously solving the problem of heat generation in the hydraulic system. By adopting the proportional flow valve, the flow rate of the hydraulic assist steering system is adjusted to achieve the purpose of variable assist steering and improve the operability of vehicle steering.

Description

Technical Field

[0001] The present invention belongs to the technical field of vehicle driving assistance, and particularly relates to a novel variable-assist hydraulic steering system. Background Art

[0002] For medium and heavy-duty vehicles, due to the excessive load on the steering axle, a large steering torque is required during steering, and the driver feels heavy when operating the steering. Therefore, the hydraulic power steering system is widely used in medium and heavy-duty vehicles. However, the existing medium and heavy-duty vehicles adopt a constant-assist hydraulic steering system, where the assist is constant during the steering process, resulting in heavy steering at low speeds or a floating feeling at high speeds. In addition, in order to meet the lightness of steering, a steering pump with a relatively large displacement is generally selected, causing large energy losses in the system. Summary of the Invention

[0003] The present invention provides a hydraulic power steering system to optimize the steering operation of medium and heavy-duty vehicles and reduce the energy loss of the system.

[0004] To solve the problems in the above background art, the present invention is realized through the following technical solutions:

[0005] A novel variable-assist hydraulic steering system includes a hydraulic circuit and a steering controller;

[0006] The hydraulic circuit includes a steering pump, a hydraulic power steering gear, a pressure limiting valve, a steering assist cylinder, a differential, and a proportional flow valve. The steering pump is connected to the engine;

[0007] The proportional flow valve is connected in parallel with the hydraulic power steering gear to form a circuit, and then connected to the steering controller, and is controlled by the steering controller;

[0008] The differential is connected in series with the hydraulic power steering gear to access the hydraulic network.

[0009] As a further description of the invention: The differential includes two output oil ports, two input oil ports, a differential circuit, and a booster.

[0010] As a further description of the invention: The booster includes two pistons, the surface area ratios of the two pistons are different, and the two pistons are rigidly connected.

[0011] As a further description of the invention: When the engine is in a low-speed operating condition, the differential circuit connects the rodless cavity and the rod cavity of the steering assist cylinder. When the engine is in a high-speed operating condition, the rodless cavity and the rod cavity of the steering assist cylinder are in an independent state, and the booster is used to conduct the pressure in the rodless cavity to the rod cavity.

[0012] As a further illustration of the invention: The flow rate of the system can be changed through the proportional flow valve to generate different steering assistances.

[0013] As a further illustration of the invention: It further includes a memory, which is connected to the proportional flow valve through the steering controller. The memory includes steering wheel angle information, vehicle speed information, and engine speed information.

[0014] As a further illustration of the invention: A pressure limiting valve is provided in the hydraulic circuit, and a pressure value is preset thereon. When the system pressure reaches the preset pressure value, the excess hydraulic oil is released and returned to the steering oil tank.

[0015] Compared with the prior art, the present invention has the following beneficial technical effects:

[0016] 1. The use of a differential ensures that the lightness of vehicle steering is not affected when the displacement of the oil pump is reduced, thereby achieving the purpose of reducing the energy loss of the hydraulic power steering system and simultaneously solving the problem of heat generation in the hydraulic system; The use of a proportional flow valve to adjust the flow rate of the hydraulic power steering system to achieve the purpose of variable assist steering and improve the operability of vehicle steering. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of the implementation mode of the present invention;

[0018] Figure 2 Schematic diagram of the implementation principle of the present invention on a vehicle;

[0019] Figure 3 Schematic diagram of the principle of the differential in the present invention;

[0020] Figure 4 Schematic diagram of the control principle of the proportional flow valve in the present invention.

[0021] DESCRIPTION OF THE REFERENCE NUMERALS

[0022] 1. Engine; 2. Hydraulic power steering gear; 3. Steering assist cylinder; 4. Differential; 41. Supercharger; 42. First cut-off valve; 43. Second cut-off valve; 44. Drain valve; 5. Pressure limiting valve; 6. Proportional flow valve; 7. Steering controller; 8. Steering pump; 9. Memory; 91. Steering wheel angle information; 92. Vehicle speed information; 93. Engine speed information. DETAILED DESCRIPTION OF THE INVENTION

[0023] In order to more clearly understand the above objects, features, and advantages of the present invention, the present invention will be described in detail below with reference to the drawings and specific embodiments. It should be noted that, without conflict, the embodiments of the present application and the features in the embodiments can be combined with each other.

[0024] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the inventive product is customarily placed during use. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention. In addition, the terms "first", "second", "third", etc. are only used for descriptive distinction and should not be construed as indicating or implying relative importance.

[0025] In addition, terms such as "horizontal" and "vertical" do not mean that the components are required to be absolutely horizontal or hanging vertically, but may be slightly inclined. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but may be slightly inclined.

[0026] In the description of the present invention, it should also be noted that unless otherwise clearly specified and defined, the terms "set", "installed", "connected", "connected" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0027] As Figures 1 to 4 shown, a new type of variable assist hydraulic steering system includes a hydraulic circuit and a steering controller 7.

[0028] Specifically, the hydraulic circuit includes a steering pump 8, a hydraulic power steering gear 2, a pressure limiting valve 5, a steering assist cylinder 3, a differential 4, and a proportional flow valve 6. The steering pump 8 is connected to the engine 1. The proportional flow valve 6 is connected in parallel with the hydraulic power steering gear 2 to form a circuit, and then connected to the steering controller 7 and controlled by the steering controller 7. The differential 4 is connected in series with the hydraulic power steering gear 2 to access the hydraulic network. By means of the proportional flow valve 6, the flow rate of the system can be changed to generate different steering assist forces.

[0029] The differential 4 includes two output oil ports, two input oil ports, a differential circuit and a booster 41. The booster 41 includes two pistons with different surface area ratios. The two pistons are rigidly connected. When the engine is in a low-speed operating condition, the differential circuit connects the rodless chamber and the rod chamber of the steering assist cylinder 3. When the engine is in a high-speed operating condition, the rodless chamber and the rod chamber of the steering assist cylinder are in an independent state. The booster 41 is used to conduct the pressure in the rodless chamber to the rod chamber.

[0030] A new type of variable assist hydraulic steering system provided by this application further includes a memory 9. The memory 9 is connected to the proportional flow valve 6 through the steering controller 7. The memory 9 includes steering wheel angle information 91, vehicle speed information 92 and engine speed information 93.

[0031] A pressure limiting valve 5 is provided in the hydraulic circuit, and a pressure value is preset thereon. When the system pressure reaches the preset pressure value, the excess hydraulic oil is released and returned to the steering oil tank.

[0032] Working principle;

[0033] As Figure 2 shown, the engine 1 transmits the prime power through the steering pump 8, via the hydraulic power steering gear 2 and the differential 4 to the steering assist cylinder 3. When the vehicle steers under the low-speed operating condition of the engine 1, the first cut-off valve 42 or the second cut-off valve 43 of the differential 4 is energized to connect the two chambers of the steering assist cylinder 3. When the vehicle steers under the high-speed operating condition of the engine 1, the first cut-off valve 42 and the second cut-off valve 43 of the differential 4 are de-energized, and the two chambers of the assist cylinder are in an independent state. The existence of the differential circuit ensures that the displacement of the oil pump is reduced without affecting the steering lightness. When the vehicle steers, the proportional flow valve 6 is used to change the flow rate of the system in real time to optimize its steering operability.

[0034] As Figure 3 shown, in order to transfer the pressure in the rodless chamber of the steering assist cylinder 3 to the rod chamber, a booster 41 is provided for the differential circuit. The two pistons with different surface area ratios in the booster 41 are rigidly connected. To ensure the normal operation of the differential circuit, an oil drain valve 44 is also provided in the differential 4. The oil drain valve 44 and the second cut-off valve 43 are energized and de-energized simultaneously. After de-energization, the oil in the sensitive chamber of the booster 41 is released through the oil drain valve 44 and returned to the steering oil tank. The differential 4 has polarity. The A port of the differential 4 is connected to the rodless chamber of the assist cylinder, and the B port is connected to the rod chamber.

[0035] As Figure 4 shown, the steering wheel angle information 91, vehicle speed information 92 and engine speed information 93 in the memory 9 are transmitted to the proportional flow valve 6 through the steering controller 7 to adjust the system flow rate to the optimal state.

[0036] The embodiments given above are the preferred examples for implementing the present invention, and the present invention is not limited to the above embodiments. Any non-essential addition or replacement made by those skilled in the art based on the technical features of the technical solution of the present invention shall fall within the protection scope of the present invention.

Claims

1. A novel variable assist hydraulic steering system, characterized in that: It includes a hydraulic circuit and a steering controller; The hydraulic circuit includes a steering pump, a hydraulic power steering gear, a pressure limiting valve, a steering assist cylinder, a differential, and a proportional flow valve. The steering pump is connected to the engine; The proportional flow valve is connected in parallel with the hydraulic power steering gear to form a circuit, and then connected to the steering controller and controlled by the steering controller; The differential is connected in series with the hydraulic power steering gear to access the hydraulic network; The differential includes two output oil ports, two input oil ports, a differential circuit, and a booster; The booster includes two pistons. The surface areas of the two pistons are different, and the two pistons are rigidly connected; When the engine is in a low-speed operating condition, the differential circuit connects the rodless cavity and the rod cavity of the steering assist cylinder. When the engine is in a high-speed operating condition, the rodless cavity and the rod cavity of the steering assist cylinder are in an independent state. The booster is used to conduct the pressure in the rodless cavity to the rod cavity.

2. A novel variable-assist hydraulic steering system according to claim 1, characterized in that: The flow rate of the system can be changed through the proportional flow valve to generate different steering assists.

3. A novel variable assist hydraulic steering system according to claim 1, characterized in that: It further includes a memory. The memory is connected to the proportional flow valve through the steering controller. The memory includes steering wheel angle information, vehicle speed information, and engine speed information.

4. A novel variable assist hydraulic steering system according to claim 1, characterized in that: A pressure limiting valve is provided in the hydraulic circuit, and a pressure value is preset on it. When the system pressure reaches the preset pressure value, the excess hydraulic oil is released and returned to the steering oil tank.

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