A straddle carrier and its steering control system

Abstract

The present invention discloses a straddle carrier and a steering control system thereof, wherein the straddle carrier comprises a motor pump group and a plurality of independent steering control systems connected to the motor pump group, wherein the steering control system comprises a one-way valve, a steering valve, an accumulator, and a steering cylinder. The input end of the one-way valve is connected to the motor pump group, and the output end thereof is connected to the steering valve and the accumulator, so that high-pressure oil enters the accumulator from the motor pump group, and the steering valve is further connected to the steering cylinder. When the straddle carrier is turning, the accumulator releases pressure to allow the high-pressure oil to enter the steering cylinder. The present invention is intended to overcome the characteristics of the conventional hydraulic steering system, such as high energy consumption, poor road feel, and delayed response, and also to enable the straddle carrier to have the characteristics of maneuverability, high efficiency, and good stability.

Description

Technical Field

[0001] The present invention relates to a port operation vehicle and a control system thereof, and more particularly to a straddle carrier and a steering control system thereof. Background Art

[0002] Container straddle carriers are the main type of container handling equipment, usually responsible for horizontal transportation from the front of the wharf to the yard and container stacking at the yard. Container straddle carriers are widely used due to their flexibility, high efficiency, good stability and low wheel pressure. Container straddle carrier operations are very beneficial to improving the loading and unloading efficiency of the front equipment at the wharf. Since its advent in the 1960s, container straddle carriers have become key equipment for container terminals and yards after decades of development, just like rubber-tyred container gantry cranes.

[0003] Due to the improvement of container straddle carrier technology and the development of related technologies such as hydraulics, container straddle carriers are showing a trend of diversification. In terms of main engine configuration, the single-host type still occupies a large market. In this type of straddle carrier, the engine is arranged on the top of the straddle carrier, which is convenient for control and maintenance, but the center of mass is increased. For the straddle carrier of type II, its excessively high center of mass affects the driving safety of the straddle carrier. In a dual-host straddle carrier, two engines are generally arranged between the door legs on both sides of the gantry. Since the engine is arranged at a lower position, the center of mass position of the whole machine is lowered, and the safety and stability are significantly improved, but at the same time it brings certain difficulties to maintenance and control. In terms of transmission mode, in addition to traditional mechanical and hydromechanical transmission modes, hydraulic transmission and electrical transmission modes have developed rapidly.

[0004] With the maturity of intelligent driving technology, a wave of automated terminal construction has been set off in the world. In addition to newly built automated terminals, many traditional large container ports are also carrying out or planning automated and semi-automated transformation. As a kind of port container transportation tool, straddle carriers play a very important role in the horizontal transportation of port containers. The traditional straddle carrier wheel steering adopts a connecting rod connection, and the connecting rod is pushed by the cylinder to achieve the synchronous steering of the wheels on one side. This steering form is simple to control, but the steering form is single, and can only achieve Ackerman steering, and the steering accuracy is not high.

[0005] Modern ports have higher and higher requirements for the flexibility of handling equipment. Most traditional straddle carriers are hydraulically driven, and connecting rods are used between the wheels on each side for synchronous and differential control of the turning angle. Steering is done by the driver operating the steering wheel to send a steering signal to the steering system, the hydraulic pump provides power, and the steering valve controls the steering cylinder to drive the wheels and connecting rods to achieve the entire steering action. Due to the special structure of the straddle carrier, the power source comes from the upper platform, and the steering wheels as the actuator are on the lower trolley, passing through a long pipeline, causing loss and lag of hydraulic pressure. At the same time, the connecting rod system also has shortcomings such as poor accuracy and high retardation rate. Multiple factors cause low control accuracy, which inevitably affects the control performance of the straddle carrier. At the same time, the lack of a suitable control interface makes it difficult for the unit to meet the coordinated control requirements of the entire system, hindering the further improvement of the automation level of the control system. Summary of the invention

[0006] In view of the above problems existing in the prior art, an object of the present invention is to provide a straddle carrier and a steering control system thereof.

[0007] To achieve the above object, the present invention adopts the following technical solution:

[0008] A straddle carrier includes a motor pump group and a plurality of independent steering control systems connected to the motor pump group, wherein the steering control system includes a one-way valve, a steering valve, an accumulator, and a steering oil cylinder. The input end of the one-way valve is connected to the motor pump group, and the output end thereof is connected to the steering valve and the accumulator, so that high-pressure oil enters the accumulator from the motor pump group, and the steering valve is further connected to the steering oil cylinder. When the straddle carrier is turning, the accumulator releases pressure so that the high-pressure oil enters the steering oil cylinder.

[0009] Furthermore, during the movement of the straddle carrier, the motor pump unit continuously inputs high-pressure oil of a certain flow rate and pressure to each steering control system, and the accumulator corresponding to each steering control system receives and stores the high-pressure oil.

[0010] Furthermore, during the steering process and the holding process, the motor pump unit continuously fills the accumulator that loses energy with high-pressure oil.

[0011] Furthermore, the peak power required by the steering cylinder when turning is provided by the pressure released by the accumulator.

[0012] Further, the amount of pressure released by the accumulator depends on the angle at which the wheel corresponding to the accumulator deflects during steering.

[0013] To achieve the above object, the present invention also adopts the following technical solution:

[0014] An independent steering control system for a straddle carrier includes a one-way valve, a steering valve, an accumulator, and a steering cylinder. The input end of the one-way valve is connected to the motor pump group of the straddle carrier, and the output end thereof is connected to the steering valve and the accumulator, so that high-pressure oil enters the accumulator from the motor pump group, and the steering valve is further connected to the steering cylinder. When the straddle carrier is turning, the accumulator releases pressure to allow high-pressure oil to enter the steering cylinder.

[0015] Furthermore, during the movement of the straddle carrier, the motor pump unit continuously inputs high-pressure oil of a certain flow rate and pressure to each steering control system, and the accumulator corresponding to each steering control system receives and stores the high-pressure oil.

[0016] Furthermore, during the steering process and the holding process, the motor pump unit continuously fills the accumulator that loses energy with high-pressure oil.

[0017] Furthermore, the peak power required by the steering cylinder when turning is provided by the pressure released by the accumulator.

[0018] Further, the amount of pressure released by the accumulator depends on the angle at which the wheel corresponding to the accumulator deflects during steering.

[0019] In the above technical scheme, the present invention aims to overcome the characteristics of the conventional hydraulic steering system, such as high energy consumption, poor road feel, and delayed response, and also aims to make the straddle carrier maneuverable, efficient, and stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a structural schematic diagram of the steering control system of the straddle carrier of the present invention. DETAILED DESCRIPTION

[0021] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0022] The invention discloses a straddle carrier and a steering control system used in the straddle carrier, which improve the problems of response lag and inaccurate control caused by using mechanical connecting rods between wheels in the existing steering.

[0023] Compared with the prior art, the present invention eliminates the fixed mechanical link between wheels and uses independent steering controlled by hydraulic valves. Secondly, the present invention uses a combination of large and small pumps and accumulators according to the different requirements of each actuator for hydraulic power. According to the actual load and steering angle, the accumulator supplies oil to the cylinder at the moment of steering. During the steering process, the oil pump replenishes the flow consumption of the accumulator. Since each wheel is equipped with an accumulator, the accumulator will automatically match the pressure and flow required by the steering cylinder, and the wheels will not interfere with each other.

[0024] As one aspect of the present invention, referring to Figure 1The present invention first discloses a straddle carrier. Inside the straddle carrier, a plurality of independent steering control systems are connected to a motor pump group 1. The plurality of steering control systems can be connected to the motor pump group 1 in parallel, and each steering control system corresponds to a wheel of the straddle carrier, so in the straddle carrier, the number of steering control systems corresponds to the number of wheels. Each steering control system includes a one-way valve 2, a steering valve 3, an accumulator 4, and a steering cylinder 5. The input end of the one-way valve 2 is connected to the motor pump group 1, and the output end of the one-way valve 2 is connected to the steering valve 3 and the accumulator 4, so that high-pressure oil enters the accumulator 4 from the motor pump group 1, and the steering valve 3 is further connected to the steering cylinder 5.

[0025] As another aspect of the present invention, continue to refer to Figure 1 The present invention also discloses an independent steering control system. Figure 1 As shown, the steering control system includes a one-way valve 2, a steering valve 3, an accumulator 4, and a steering cylinder 5. The input end of the one-way valve 2 is connected to the motor pump group 1, and the output end of the one-way valve 2 is connected to the steering valve 3 and the accumulator 4, so that high-pressure oil enters the accumulator 4 from the motor pump group 1, and the steering valve 3 is further connected to the steering cylinder 5.

[0026] During the movement of the straddle carrier, the motor pump unit 1 continuously inputs flow and pressure to each system at a low flow rate with high pressure. The accumulators 4 corresponding to the wheels of each trolley receive and store the flow and pressure. After the driver sends a steering signal, the steering controller sends different deflection instructions to each steering valve 3. Each wheel has a different flow demand. At this time, the pressure of the accumulator 4 begins to be released, and the high-pressure oil enters the steering cylinder 5 to drive the wheels to complete the steering.

[0027] When the straddle carrier is turning, the accumulator 4 releases pressure to allow high-pressure oil to enter the steering cylinder 5, and the amount of pressure released by the accumulator 4 depends on the deflection angle of the wheel corresponding to the accumulator 4 when turning. For example, when the steering signal is given to the steering gear, in fact, the deflection angle of each wheel is different according to the steering mode. As an embodiment of the present invention, when the turning angle of the inner wheels on both sides is 30°, the turning angle of the middle inner wheel needs to be turned to 16°, the turning angle of the outer wheels on both sides needs to be turned to 20°, and the turning angle of the middle outer wheel needs to be 10°. In this way, the four different steering angles need to be completed at the same time, and the steering speed between each wheel is also different. The corresponding flow distribution must be processed differently. At this time, in the straddle carrier, the accumulator 4 of each steering control system will release different amounts of oil to its corresponding steering cylinder 5 according to needs for matching.

[0028] Since the friction of each wheel on the ground is different, the pressure reflected in the steering cylinder 5 is also different. If the hydraulic system is uniformly supplied by an oil pump, the system will give priority to outputting flow to the low-pressure cylinder, resulting in insufficient flow in some high-pressure cylinders. In order to ensure normal operation, the power of the hydraulic pump source must meet the coexistence of maximum flow and pressure, so the power of the motor and the pump needs to be increased. The present invention sets up an accumulator 4 for the steering cylinder 5 separately. At the moment of steering, the maximum flow is supplied by the accumulator 4 to ensure the normal operation of each steering cylinder 5. After the steering action is completed, a smaller power oil pump is used to supplement the pressure of the accumulator 4 with a small flow to ensure the normal power requirement for the next steering action.

[0029] Therefore, during the steering process and the holding process, the motor pump unit 1 continuously charges the energy accumulator 4 which loses energy, so as to prepare for the next steering. The peak power required by the steering cylinder 5 when turning is provided by the pressure released by the accumulator 4, thus ensuring the smoothness and low power of the entire hydraulic system.

[0030] The present invention adopts an independent steering control system for each wheel of the straddle carrier, which has the advantages that the oil pump and the accumulator jointly provide steering oil to ensure timely response of the steering action, and each wheel has an independent steering cylinder to control the steering, so that each wheel has a different steering angle.

[0031] In summary, the straddle carrier and the steering control system thereof of the present invention have the following beneficial effects:

[0032] 1. Use the energy of the motor pump group in a staggered manner, and use lower power consumption to meet the maximum instantaneous consumption of each mechanism.

[0033] 2. Reduce the power pulsation of the hydraulic system, make the energy transmission process of the hydraulic system smoother, and reduce hydraulic shock.

[0034] 3. When steering is required, the accumulator provides steering power to the wheels, which makes the straddle carrier's steering response quick.

[0035] Those skilled in the art should recognize that the above embodiments are only used to illustrate the present invention, and are not intended to limit the present invention. As long as they are within the spirit of the present invention, any changes or modifications to the above embodiments will fall within the scope of the claims of the present invention.

Claims

1. A straddle carrier, comprising a motor pump assembly and 8 independent steering control systems connected to the motor pump assembly, characterized in that: Each of the 8 independent steering control systems includes: Check valve, steering valve, accumulator, steering cylinder; The input end of the one-way valve is connected to the motor pump group, and the output end thereof is connected to the steering valve and the accumulator, so that the high-pressure oil enters the accumulator from the motor pump group, and the steering valve is further connected to the steering cylinder; During the movement of the straddle carrier, the motor pump group continuously inputs high-pressure oil of a certain flow rate and pressure to each steering control system, and the accumulator corresponding to each steering control system receives and stores the high-pressure oil. When the straddle carrier is turning, the accumulator releases pressure to allow high-pressure oil to enter the steering cylinder. The amount of pressure released by the accumulator depends on the deflection angle of the wheel corresponding to the accumulator when turning. Each accumulator of the steering control system releases different amounts of oil to its corresponding steering cylinder as needed to match the oil pressure. After the steering signal is issued, the steering control system sends different deflection instructions to each steering valve. Each wheel has different flow requirements. At this time, the pressure in the accumulator begins to release, and the high-pressure oil enters the steering cylinder to drive the wheels and complete the steering.

2. The straddle carrier according to claim 1, characterized in that: When the turning angle of the inner wheels on both sides is 30°, the turning angle of the middle inner wheel needs to be turned to 16°, the turning angle of the outer wheels on both sides is turned to 20°, and the turning angle of the middle outer wheel needs to be 10°. These four different steering angles are completed at the same time, and the steering speeds between the wheels are also different. The corresponding flow distribution is differentiated, and the accumulator of each steering control system releases different amounts of oil to its corresponding steering cylinder for matching as needed.

3. The straddle carrier according to claim 1, characterized in that: During the steering and holding process, the motor pump unit continuously fills the energy-losing accumulator with high-pressure oil.

4. The straddle carrier according to claim 1, characterized in that: The peak power required by the steering cylinder when turning is provided by the pressure released by the accumulator.

5. An independent steering control system for a straddle carrier, characterized in that: include: Check valve, steering valve, accumulator, steering cylinder; The input end of the one-way valve is connected to the motor pump group of the straddle carrier, and the output end thereof is connected to the steering valve and the accumulator, so that the high-pressure oil enters the accumulator from the motor pump group, and the steering valve is further connected to the steering cylinder; During the movement of the straddle carrier, the motor pump group continuously inputs high-pressure oil of a certain flow rate and pressure to each steering control system, and the accumulator corresponding to each steering control system receives and stores the high-pressure oil. When the straddle carrier is turning, the accumulator releases pressure to allow high-pressure oil to enter the steering cylinder. The amount of pressure released by the accumulator depends on the deflection angle of the wheel corresponding to the accumulator when turning. Each accumulator of the steering control system releases different amounts of oil to its corresponding steering cylinder as needed to match the oil pressure. After the steering signal is issued, the steering control system sends different deflection instructions to each steering valve. Each wheel has different flow requirements. At this time, the pressure in the accumulator begins to release, and the high-pressure oil enters the steering cylinder to drive the wheels and complete the steering.

6. The independent steering control system according to claim 5, characterized in that: When the turning angle of the inner wheels on both sides is 30°, the turning angle of the middle inner wheel needs to be turned to 16°, the turning angle of the outer wheels on both sides is turned to 20°, and the turning angle of the middle outer wheel needs to be 10°. These four different steering angles are completed at the same time, and the steering speeds between the wheels are also different. The corresponding flow distribution is differentiated, and the accumulator of each steering control system releases different amounts of oil to its corresponding steering cylinder for matching as needed.

7. The independent steering control system according to claim 5, characterized in that: During the steering and holding process, the motor pump unit continuously fills the energy-losing accumulator with high-pressure oil.

8. The independent steering control system according to claim 5, characterized in that: The peak power required by the steering cylinder when turning is provided by the pressure released by the accumulator.

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