阅读说明：本技术 一种应急拖车控制系统 (Emergency trailer control system ) 是由 堵利宾 周小磊 贾连辉 郑博 庞文卓 李胜玺 黄政委 于 2021-08-30 设计创作，主要内容包括：本发明提出了一种应急拖车控制系统,包括发动机、蓄电池和控制器,所述蓄电池与直流电机相连接,直流电机与应急液压泵相连接,应急液压泵分别与闭式液压泵和驻车控制及驱动装置相连接,闭式液压泵分别与行驶驱动液压马达和发动机相连接；发动机分别与制动液压泵和转向液压泵相连接,制动液压泵分别与驻车控制及驱动装置、制动控制及驱动装置相连接,转向液压泵与转向控制及驱动装置相连接,控制器分别与发动机、直流电机、闭式液压泵、驻车控制及驱动装置、制动控制及驱动装置和转向控制及驱动装置相连接。本发明可以实现自动驻车解除、闭式泵排量控制等,可长时间连续工作,功耗低；驻车解除后拖车过程可以实现转向和制动的功能。(The invention provides an emergency trailer control system, which comprises an engine, a storage battery and a controller, wherein the storage battery is connected with a direct current motor, the direct current motor is connected with an emergency hydraulic pump, the emergency hydraulic pump is respectively connected with a closed hydraulic pump and a parking control and driving device, and the closed hydraulic pump is respectively connected with a driving hydraulic motor and the engine; the engine is respectively connected with a braking hydraulic pump and a steering hydraulic pump, the braking hydraulic pump is respectively connected with a parking control and driving device and a braking control and driving device, the steering hydraulic pump is connected with a steering control and driving device, and the controller is respectively connected with the engine, the direct current motor, the closed hydraulic pump, the parking control and driving device, the braking control and driving device and the steering control and driving device. The invention can realize automatic parking release, closed pump displacement control and the like, can continuously work for a long time and has low power consumption; the trailer process can realize the functions of steering and braking after the parking is released.)

1. An emergency trailer control system is characterized by comprising an engine, a storage battery and a controller, wherein the storage battery is connected with a direct current motor, the direct current motor is connected with an emergency hydraulic pump, the emergency hydraulic pump is respectively connected with a closed hydraulic pump and a parking control and driving device, and the closed hydraulic pump is respectively connected with a driving hydraulic motor and the engine; the engine is respectively connected with a braking hydraulic pump and a steering hydraulic pump, the braking hydraulic pump is respectively connected with a parking control and driving device and a braking control and driving device, the steering hydraulic pump is connected with a steering control and driving device, and the controller is respectively connected with the engine, the direct current motor, the closed hydraulic pump, the parking control and driving device, the braking control and driving device and the steering control and driving device.

2. The emergency trailer control system of claim 1, wherein the engine is a diesel engine.

3. The emergency trailer control system of claim 2, wherein the diesel engine is connected to a storage generator, the storage generator being connected to a storage battery; the storage battery is connected with the controller.

4. The emergency trailer control system of claim 1 or 3, wherein the emergency hydraulic pump is connected to a control valve set, the control valve set being connected to the parking control and drive device, the control valve set being connected to the controller.

5. The emergency trailer control system of claim 4, wherein the closed hydraulic pump is connected to the travel drive hydraulic motor through a hydraulic circuit, the brake hydraulic pump is connected to the parking control and drive device and the brake control and drive device through a hydraulic circuit, respectively, and the steering hydraulic pump is connected to the steering control and drive device through a hydraulic circuit.

6. The emergency trailer control system of claim 1, wherein a rotation speed sensor is arranged on the traveling driving hydraulic motor, the rotation speed sensor is connected with the controller, the rotation speed sensor is used for detecting the rotation speed of the traveling driving hydraulic motor, and the controller controls the displacement of the closed hydraulic pump according to the rotation speed and indirectly controls the rotation speed of the closed hydraulic pump and the engine.

7. The emergency trailer control system of claim 6, wherein the parking control and drive device is provided with a pressure sensor, and the pressure sensor is connected with the controller; the pressure sensor detects parking oil supply pressure in real time, and when the parking oil supply pressure is lower than a set threshold value, the controller controls the direct current motor to drive the emergency hydraulic pump to start; the set threshold is the lowest pressure of the parking clutch disengagement.

8. The emergency trailer control system of claim 1 or 7, wherein the steering control and drive device comprises a hydraulic steering gear and a hydraulic cylinder, the steering hydraulic pump is connected with the hydraulic steering gear through a steering control valve, and the hydraulic steering gear is connected with the hydraulic cylinder; and hydraulic oil output by the steering hydraulic pump enters the hydraulic steering gear through the steering control valve, and the hydraulic steering gear outputs the hydraulic oil to drive the hydraulic oil cylinder to steer.

9. The emergency trailer control system of any one of claims 1 to 3 or 5 to 7, operating by:

after the trailer is started and enabled, the controller sends a control signal to start the direct current motor, the direct current motor is powered by the storage battery and drives the emergency hydraulic pump to work, the emergency hydraulic pump provides hydraulic power for the closed hydraulic pump and the parking control and driving device, variable displacement of the closed hydraulic pump and parking release are realized, and the vehicle is dragged;

the controller adjusts the displacement of the closed hydraulic pump, so that the rotating speed of the engine works in a preset range, the engine is driven to rotate, the electricity storage generator generates electricity to store electricity for the storage battery, meanwhile, the engine rotates to drive the braking hydraulic pump and the steering hydraulic pump to work, the braking hydraulic pump provides braking hydraulic oil for the braking control and driving device and the parking control and driving device, the steering hydraulic pump provides steering hydraulic oil for the steering control and driving device, at the moment, the direct-current motor stops, and the vehicle or equipment can still work normally.

10. The emergency trailer control system of claim 9, wherein after the vehicle or equipment is towed, the travel drive hydraulic motor is rotated, and hydraulic oil is driven from the port R of the travel drive hydraulic motor to the port a of the closed hydraulic pump to rotate, and then is driven to rotate through the port B of the closed hydraulic pump to the port L of the travel drive hydraulic motor; after the trailer mode is started, the direct current motor drives the emergency hydraulic pump to work, meanwhile, an electromagnetic directional valve in the control valve group is electrified and reversed, hydraulic oil is output to a parking brake of a parking control and driving device through a shuttle valve, parking release is achieved, meanwhile, the hydraulic oil output from a port B of the control valve group supplies oil to Ps of a closed hydraulic pump, a variable oil source is provided for the closed hydraulic pump, the closed hydraulic pump drives an engine to rotate, the engine rotates to drive a braking hydraulic pump and a steering hydraulic pump which are connected with the engine to work, the hydraulic oil flows to a braking control valve of the braking control and driving device and a steering control valve of the steering control and driving device respectively, and the hydraulic oil sources of driving braking and steering are achieved respectively.

Technical Field

The invention relates to the technical field of hydraulic drive, in particular to an emergency trailer control system which can be applied to a hydraulic drive running vehicle.

Background

At present, the diesel engine and the diesel engine management system trouble of the wheeled hydraulic drive of engineering vehicle of traveling are higher in vehicle trouble ratio, and when the diesel engine trouble, the vehicle will thoroughly lose power to even if can't carry out the parking and remove, even if remove the parking through mechanical emergency means, also can't provide the oil supply for hydraulic steering, hydraulic braking, can't realize transferring the necessary steering and braking demand of trailer in the true sense, the trailer will endanger vehicle and personnel's safety by force.

The invention patent application with the application number of 201511000782.X discloses a vehicle emergency trailer starting system, wherein an engine is started to work through a control unit, the rotating speed of a gearbox is detected through a rotating speed sensor so as to obtain the rotating speed of the engine, gear shifting of the gearbox is realized through a gear shifting control valve, oil charging and discharging of a clutch are controlled through a locking control valve so as to realize connection or disconnection of the engine and the gearbox, a rear hydraulic oil pump is used for driving hydraulic oil in a vehicle to circulate, and hydraulic power is provided for the work of the gearbox and the clutch; the automatic gearbox vehicle starting system has the advantages that the trailer starting function is provided for the vehicle loaded with the automatic gearbox, the trailer is started, the intelligent disconnection and the mechanical connection of the engine are realized after the vehicle is started successfully, the vehicle collision danger is prevented, and the vehicle intelligent level is improved. However, the invention only realizes the power transmission connection of the transmission system between the engine and the wheels in the trailer state, and cannot ensure that power or a power source can be provided for steering and braking.

Disclosure of Invention

The invention provides an emergency trailer control system, aiming at solving the technical problems that the existing hydraulic drive vehicle cannot be parked and released after a fault and cannot be hydraulically steered and braked, and solving the problems that a wheel type hydraulic drive running system cannot be started when a diesel engine fails to work or is soaked in water or the like, and when the diesel engine needs to be urgently dragged to move to avoid a place or needs to be dragged to a repair place under the condition of losing power, the emergency trailer control system can provide necessary functions of parking release, power steering, power braking and the like.

In order to achieve the purpose, the technical scheme of the invention is realized as follows: an emergency trailer control system comprises an engine, a storage battery and a controller, wherein the storage battery is connected with a direct current motor, the direct current motor is connected with an emergency hydraulic pump, the emergency hydraulic pump is respectively connected with a closed hydraulic pump and a parking control and driving device, and the closed hydraulic pump is respectively connected with a driving hydraulic motor and the engine; the engine is respectively connected with a braking hydraulic pump and a steering hydraulic pump, the braking hydraulic pump is respectively connected with a parking control and driving device and a braking control and driving device, the steering hydraulic pump is connected with a steering control and driving device, and the controller is respectively connected with the engine, the direct current motor, the closed hydraulic pump, the parking control and driving device, the braking control and driving device and the steering control and driving device.

Preferably, the engine is a diesel engine. The diesel engine can realize the starting and the power generation of vehicles or equipment.

Preferably, the diesel engine is connected with an electric storage generator, and the electric storage generator is connected with a storage battery; the storage battery is connected with the controller, and the storage battery box controller provides electric energy.

Preferably, the emergency hydraulic pump is connected with a control valve bank, the control valve bank is connected with a parking control and driving device, and the control valve bank is connected with a controller. The parking control and the starting of the driving device can be controlled through the control valve group, and parking releasing is achieved.

Preferably, the closed hydraulic pump is connected with the traveling driving hydraulic motor through a hydraulic circuit, the braking hydraulic pump is respectively connected with the parking control and driving device and the braking control and driving device through the hydraulic circuit, and the steering hydraulic pump is connected with the steering control and driving device through the hydraulic circuit. Each device is actuated by a hydraulic circuit, thereby performing parking release, braking, and steering.

Preferably, a rotation speed sensor is arranged on the walking driving hydraulic motor and connected with the controller, the rotation speed sensor is used for detecting the rotation speed of the walking driving hydraulic motor, and the controller controls the discharge capacity of the closed hydraulic pump according to the rotation speed and indirectly controls the rotation speed of the closed hydraulic pump and the rotation speed of the engine.

Preferably, a pressure sensor is arranged on the parking control and drive device and is connected with the controller; the pressure sensor detects parking oil supply pressure in real time, and when the parking oil supply pressure is lower than a set threshold value, the controller controls the direct current motor to drive the emergency hydraulic pump to start; the set threshold is the lowest pressure of the parking clutch disengagement.

Preferably, the steering control and drive device comprises a hydraulic steering gear and a hydraulic oil cylinder, the steering hydraulic pump is connected with the hydraulic steering gear through a steering control valve, and the hydraulic steering gear is connected with the hydraulic oil cylinder; and hydraulic oil output by the steering hydraulic pump enters the hydraulic steering gear through the steering control valve, and the hydraulic steering gear outputs the hydraulic oil to drive the hydraulic oil cylinder to steer.

Preferably, the working method comprises the following steps: after the trailer is started and enabled, the controller sends a control signal to start the direct current motor, the direct current motor is powered by the storage battery and drives the emergency hydraulic pump to work, the emergency hydraulic pump provides hydraulic power for the closed hydraulic pump and the parking control and driving device, variable displacement of the closed hydraulic pump and parking release are realized, and the vehicle is dragged;

the controller adjusts the displacement of the closed hydraulic pump, so that the rotating speed of the engine works in a preset range, the engine is driven to rotate, the electricity storage generator generates electricity to store electricity for the storage battery, meanwhile, the engine rotates to drive the braking hydraulic pump and the steering hydraulic pump to work, the braking hydraulic pump provides braking hydraulic oil for the braking control and driving device and the parking control and driving device, the steering hydraulic pump provides steering hydraulic oil for the steering control and driving device, at the moment, the direct-current motor stops, and the vehicle or equipment can still work normally.

Preferably, after the vehicle or equipment is dragged, the driving hydraulic motor rotates, the hydraulic oil drives the closed hydraulic pump to rotate from the port R of the driving hydraulic motor to the port A of the closed hydraulic pump, and then the hydraulic oil passes through the port B of the closed hydraulic pump and then flows to the port L of the driving hydraulic motor; after the trailer mode is started, the direct current motor drives the emergency hydraulic pump to work, meanwhile, an electromagnetic directional valve of the emergency control valve group is electrified and reversed, hydraulic oil is output to a parking brake of a parking control and driving device through a shuttle valve, parking release is achieved, meanwhile, the hydraulic oil output from a port B of the emergency control valve group supplies oil to Ps of a closed hydraulic pump, a variable oil source is provided for the closed hydraulic pump, the closed hydraulic pump drives an engine to rotate, the engine rotates to drive a brake hydraulic pump and a steering hydraulic pump connected with the engine to work, the hydraulic oil flows to a brake control valve of the brake control and driving device and a steering control valve of the steering control and driving device respectively, and the hydraulic oil sources of driving brake and steering are achieved respectively.

Compared with the prior art, the invention has the beneficial effects that:

1. the invention adopts the storage battery on the vehicle to supply power to the direct current motor, and the direct current motor drives the emergency hydraulic pump to provide an oil source for the parking control and drive device and the closed hydraulic pump by starting in a one-key trailer mode, thereby realizing automatic parking release, closed pump displacement control and the like, being capable of continuously working for a long time, and having low power consumption.

2. After the emergency trailer mode and the vehicle are dragged, the closed hydraulic pump is variable in the emergency power mode, and the driving hydraulic motor is changed into a pump working condition under the dragging condition, so that the closed hydraulic pump is driven to provide rotary driving power for the diesel engine, the diesel engine rotates to drive the electric power storage generator, the steering hydraulic pump and the brake hydraulic pump to work, and the functions of steering, braking and the like are recovered to be normal.

3. In the emergency trailer mode, after the vehicle is dragged, and the functions of steering, braking and the like are normal, the controller can automatically adjust the discharge capacity of the closed hydraulic pump according to the dragged vehicle speed so as to stabilize the rotating speed of the diesel engine to work within a preset range, ensure that each system operates more stably and the operating efficiency of the system is higher.

4. According to the invention, in a trailer mode, after the steering and braking functions are normal, the direct current motor drives the emergency hydraulic pump to stop working so as to reduce energy consumption, meanwhile, the controller automatically monitors the parking oil supply pressure of the parking control and driving device and the oil compensation pressure of the closed hydraulic pump, and when the parking oil supply pressure and the oil compensation pressure are lower than a set threshold value, the direct current motor is automatically started to drive the emergency hydraulic pump to work so as to ensure stable, continuous and reliable working in the trailer mode.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

Fig. 1 is a schematic diagram of the present invention.

Fig. 2 is a diagram of an example of the hydraulic control of the present invention.

In the figure, 1 is a direct current motor, 2 is an emergency hydraulic pump, 3 is a driving hydraulic motor, 4 is a steering hydraulic pump, 5 is a braking hydraulic pump, 6 is a closed hydraulic pump, 7 is a parking brake, 8 is a service brake, 9 is a proportional directional valve, 10 is an electromagnetic directional valve, 11 is a shuttle valve, 12 is a hydraulic oil cylinder, and 13 is a hydraulic steering gear.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without inventive effort based on the embodiments of the present invention, are within the scope of the present invention.

As shown in fig. 1, an emergency trailer control system, including engine, battery and controller, the engine gathers the power of trailer in-process and generates electricity or starts other equipment, the controller is as the total control terminal of this system, the battery is connected with direct current motor 1, the battery provides the electric energy for direct current motor 1, drive it and carry out work, direct current motor is connected with emergent hydraulic pump 2, direct current motor 1 drive emergent hydraulic pump 2 starts, emergent hydraulic pump 2 is connected with closed hydraulic pump 6 and parking control and drive arrangement respectively, emergent hydraulic pump 2 provides the power of the hydraulic oil of start for closed hydraulic pump 6, provide mobile hydraulic oil for drive parking control and drive arrangement simultaneously, realize the parking and remove to conveniently carry out the dragging of vehicle or equipment. The closed hydraulic pump 6 is respectively connected with the driving hydraulic motor 3 and the engine, collects power in the driving process under the action of the driving hydraulic motor 3 and transmits the power to the diesel engine. The engine is respectively and mechanically connected with the braking hydraulic pump 5 and the steering hydraulic pump 4 to realize the starting of the braking hydraulic pump and the steering hydraulic pump, the braking hydraulic pump is respectively connected with the parking control and drive device and the braking control and drive device, and the steering hydraulic pump 4 is connected with the steering control and drive device to realize the braking and the steering of the vehicle or equipment; the controller is respectively connected with the engine, the direct current motor, the closed hydraulic pump, the parking control and driving device, the braking control and driving device and the steering control and driving device. The closed hydraulic pump establishes associated control with a diesel engine, a parking control and driving device, a braking control and driving device, a steering control and driving device, a direct current motor and the like through a controller.

The storage battery can store electricity through the diesel engine.

Further, the hydraulic motor for driving the vehicle includes, but is not limited to, a single hydraulic motor, and may be a single motor, or a plurality of motors connected in series or in parallel. The travel driving hydraulic motor includes, but is not limited to, a variable displacement hydraulic motor, and may be a fixed displacement hydraulic motor.

The engine is a diesel engine. The diesel engine can realize the starting and the power generation of vehicles or equipment. The diesel engine is connected with the storage generator, the storage generator is connected with the storage battery, the storage battery collects electric energy, and meanwhile, the electric energy is supplied to the direct current motor during towing, parking release is achieved, and accordingly towing is achieved; the storage battery is connected with the controller, and the storage battery box controller provides electric energy.

The emergency hydraulic pump 2 is connected with a control valve group, the control valve group is connected with a parking control and driving device, and the control valve group is connected with a controller. The control valve group is an emergency control valve group, the emergency control valve group comprises an electromagnetic directional valve 10, the electromagnetic directional valve 10 is a two-position three-way electromagnetic directional valve, the electromagnetic directional valve 10 is connected with the emergency hydraulic pump 2, the electromagnetic directional valve 10 is connected with the Ps of the closed hydraulic pump through a one-way valve, the electromagnetic directional valve 10 is connected with the parking control and driving device through a shuttle valve 11, the shuttle valve 11 is connected with a controller, and the electromagnetic directional valve 10 is connected with an oil tank through an overflow valve. The parking control and the starting of the driving device can be controlled through the control valve group, and parking releasing is achieved. The controller controls logic solenoid valves in the parking control and driving device, the braking control and driving device and the steering control and driving device through DC 24V I/O output, and realizes the functional control of parking or braking and the like.

The closed hydraulic pump 6 is connected with a driving hydraulic motor through a hydraulic loop, the braking hydraulic pump 5 is respectively connected with a parking control and driving device and a braking control and driving device through the hydraulic loop, and the steering hydraulic pump 4 is connected with a steering control and driving device through the hydraulic loop. Each device is actuated by a hydraulic circuit, thereby performing parking release, braking, and steering. The direct current motor realizes the driving control of the closed hydraulic pump and the parking control and driving device by the emergency hydraulic pump 2 through the control valve group. In specific implementation, as shown in fig. 2, the travel driving hydraulic motor 3 reaches the R port thereof through the variable speed control valve, and then is transmitted to the closed hydraulic pump 6 through the hydraulic circuit, and the closed hydraulic pump 6 is connected to the L port of the travel driving hydraulic motor 3. The closed hydraulic pump 6 is respectively connected with the steering hydraulic pump 4 and the braking hydraulic pump 5 through a replenishing pump. The steering hydraulic pump 4 is connected with a steering control and driving device through a steering control valve. The brake hydraulic pump 5 is connected to a brake control and drive device via a brake control valve.

The walking drive hydraulic motor 3 is provided with a rotating speed sensor, the rotating speed sensor is connected with a controller, the rotating speed sensor is used for detecting the rotating speed of the walking drive hydraulic motor, the controller controls the discharge capacity of the closed hydraulic pump according to the rotating speed, and the rotating speed of the closed hydraulic pump and the rotating speed of the engine are indirectly controlled.

Preferably, a pressure sensor is arranged on the parking control and drive device and is connected with the controller; the pressure sensor detects parking oil supply pressure in real time, and when the parking oil supply pressure is lower than a set threshold value, the controller controls the direct current motor to drive the emergency hydraulic pump to start; the set threshold is the lowest pressure of the parking clutch disengagement. The set threshold is limited by the performance parameters of the particular component.

Preferably, the steering control and drive device comprises a hydraulic steering gear 13 and a hydraulic oil cylinder 12, the steering hydraulic pump 4 is connected with the hydraulic steering gear 13 through a steering control valve, and the hydraulic steering gear 13 is connected with the hydraulic oil cylinder 12; and hydraulic oil output by the steering hydraulic pump enters the hydraulic steering gear through the steering control valve, and the hydraulic steering gear outputs the hydraulic oil to drive the hydraulic oil cylinder to steer. In a specific embodiment, the steering control valve is connected to the hydraulic steering 13 via a non-return valve, and the hydraulic steering 13 is connected to the overflow valve via a throttle or directly to the tank. The output end of the hydraulic steering gear 13 is also connected with the oil tank through a one-way valve and an overflow valve. The hydraulic steering gear 13 is respectively connected with the left hydraulic oil cylinder 12 and the right hydraulic oil cylinder 12.

Preferably, the working method of the invention is as follows: after the trailer is started and enabled, the controller sends out a control signal to start the direct current motor, the direct current motor provides electric energy by the storage battery and drives the emergency hydraulic pump to work, the emergency hydraulic pump provides hydraulic power for the closed hydraulic pump and the parking control and driving device, the variable of the closed hydraulic pump is realized, the parking is removed, and the vehicle is dragged. After the emergency mode is started, the direct current motor works to drive the emergency hydraulic pump to output hydraulic oil, the hydraulic oil is sent to the parking control and driving device through the control valve group, and the parking control and driving device is a control device which is matched with original equipment and used for achieving parking, parking release, parking early warning and other functions. In the embodiment in fig. 2, the parking control and drive device comprises a parking brake 7 and a service brake 8, the parking brake 7 and the service brake 8 are connected in parallel and are both connected with the hydraulic motor 3 for driving, the parking brake 7 is connected with the shuttle valve 11, and the service brake 8 is connected with the brake solenoid valve. The direction or the discharge capacity control is realized through proportional directional control valve 9 to the closed hydraulic pump, but the prerequisite must have the hydraulic oil of drive closed hydraulic pump variable piston, and when the fault parking, the engine and the closed hydraulic pump that is connected with the engine do not rotate, can't produce the hydraulic oil of closed hydraulic pump drive variable piston drive, emergent hydraulic pump can provide the hydraulic oil of drive variable for closed hydraulic pump this moment.

The controller adjusts the displacement of the closed hydraulic pump, so that the rotating speed of the engine works in a preset range, the electric storage generator attached to the engine is driven to generate electricity to store electricity for the storage battery, meanwhile, the engine drives the braking hydraulic pump and the steering hydraulic pump to work, the braking hydraulic pump provides braking hydraulic oil for the braking control and driving device and the parking control and driving device, the steering hydraulic pump provides steering hydraulic oil for the steering control and driving device, at the moment, the direct-current motor stops, and the vehicle or equipment can still work normally.

The speed of a motor increases that is dragged, and the hydraulic oil flow of walking drive hydraulic motor output increases, and under the unchangeable condition of closed hydraulic pump discharge capacity, the speed of closed hydraulic pump gyration increases, and the engine speed of being connected with closed hydraulic pump also increases promptly, and at this moment, the rotational speed of walking drive hydraulic motor is detected through speed sensor, controls the discharge capacity of closed hydraulic pump, can indirectly control the rotational speed of closed hydraulic pump and engine.

Because engine speed is relevant with efficiency and moment of torsion, through stablizing the engine at certain rotational speed scope, be favorable to improving the efficiency and the trailer traction force of trailer, the rotational speed scope is confirmed according to the engine characteristic parameter of chooseing for use, and the engine speed scope of different specifications is different.

The rotation of the engine can drive the brake hydraulic pump and the steering hydraulic pump to rotate, the brake hydraulic pump provides hydraulic oil for the running brake, and the brake hydraulic pump mainly drives the service brake, namely the brake. The steering control and drive device of engineering equipment usually uses hydraulic steering gear and hydraulic oil cylinder to provide steering drive force, and the steering hydraulic pump is used for providing oil source for hydraulic oil cylinder of hydraulic steering actuating mechanism, the hydraulic oil output by steering hydraulic pump can be fed into hydraulic steering gear by means of steering control valve group, and the hydraulic steering gear can output hydraulic oil to drive hydraulic oil cylinder to make steering operation.

Preferably, after the vehicle or equipment is dragged, the driving hydraulic motor rotates, the hydraulic oil drives the closed hydraulic pump to rotate from the port R of the driving hydraulic motor to the port A of the closed hydraulic pump, and then the hydraulic oil passes through the port B of the closed hydraulic pump and then flows to the port L of the driving hydraulic motor; after the trailer mode is started, the direct current motor drives the emergency hydraulic pump to work, meanwhile, an electromagnetic directional valve 10 in the emergency control valve group is electrified and changes directions, a port P of the emergency control valve group is communicated with a port A of the emergency control valve group and a port B of the emergency control valve group, output hydraulic oil passes through a shuttle valve 11 to a parking brake 7 to achieve parking release, meanwhile, the hydraulic oil output from the port B of the emergency control valve group supplies oil to a port Ps of a closed hydraulic pump to provide a variable oil source for the closed hydraulic pump 6, the closed hydraulic pump 6 rotationally drives an engine to rotate, the engine rotates to drive a brake hydraulic pump 5 and a steering hydraulic pump 4 connected with the engine to work, and the hydraulic oil respectively flows to a brake control valve of a brake control and drive device and a steering control valve of a steering control and drive device to achieve hydraulic oil sources of service brake and steering.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.