Closed hydraulic system, walking system and rotary system

Abstract

The utility model relates to a closed hydraulic system, a walking system and a rotary system, which comprise a hydraulic pump component connected with a power source, an oil outlet of the hydraulic pump component is connected with an oil inlet of a hydraulic motor component through a first loop, and an oil outlet of the hydraulic motor component is connected with an oil inlet of the hydraulic pump component through a second loop; a third loop is arranged between the first loop and the second loop, and a proportional valve is arranged on the third loop. The proportional valve is additionally arranged to be communicated with the oil way between the hydraulic pump assembly and the rotary motor, the galloping phenomenon of closed system braking can be rapidly solved, the refitting cost is low, control and debugging are easy, and the matched debugging time is shortened.

Description

Technical Field

[0001] The utility model relates to the technical field of hydraulic control, in particular to a closed hydraulic system, a walking system and a rotary system. Background Art

[0002] The statements in this section merely provide background technical information related to the present invention and do not necessarily constitute prior art.

[0003] Due to the high load requirements, construction machinery uses a hydraulic pump and a hydraulic motor to form a closed hydraulic system. The hydraulic oil flows in a pump-motor-pump sequence. During this period, the hydraulic pump absorbs the engine power and converts it into hydraulic energy. The hydraulic motor converts the hydraulic energy into kinetic energy to drive the construction machinery to perform the corresponding action. The hydraulic energy is transmitted in the form of hydraulic oil flowing in the pipeline, and the main pipeline is not open to the external oil tank. Heat is dissipated only by flushing the oil replenishment circuit for a small amount of exchange. Therefore, it is called a closed hydraulic system.

[0004] The commonly used closed hydraulic system will change the displacement by controlling the swing angle of the pump to achieve system speed regulation. Since the workload is generally large, it will correspondingly bring about a larger load inertia, and braking will be achieved by reverse drag, that is, the kinetic energy of the load is used to drive the engine speed to increase. The greater the load's rotational inertia and the greater the rotation speed, the higher the load braking power peak will be, which can easily cause engine overspeed and runaway. Utility Model Content

[0005] In order to solve the technical problems existing in the above-mentioned background technology, the utility model provides a closed hydraulic system, a walking system and a slewing system, and adds an electronically controlled proportional valve to connect the oil circuit between the hydraulic pump assembly and the slewing motor. During the reverse braking of the power source, the power that cannot be absorbed is dissipated through the overflow effect after the electronically controlled proportional valve is opened to dissipate the excess kinetic energy causing the power source to overspeed, thereby quickly solving the power source overspeed and runaway phenomenon in the closed system braking.

[0006] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0007] The first aspect of the utility model provides a closed hydraulic system, including a hydraulic pump assembly connected to a power source, the oil outlet of the hydraulic pump assembly is connected to the oil inlet of a hydraulic motor assembly through a first circuit, and the oil outlet of the hydraulic motor assembly is connected to the oil inlet of the hydraulic pump assembly through a second circuit; a third circuit is provided between the first circuit and the second circuit, and a proportional valve is provided on the third circuit.

[0008] Furthermore, a sensor assembly is provided on the power source, and the sensor assembly includes a speed sensor and a torque sensor, which are used to obtain a speed signal and a torque signal transmitted from the power source to the hydraulic pump assembly.

[0009] Furthermore, the proportional valve is an electrically controlled proportional valve.

[0010] Furthermore, in the working state, the power source drives the hydraulic pump assembly to work, and the output hydraulic oil is transmitted to the hydraulic motor assembly through the first circuit. The hydraulic motor assembly drives the load to perform corresponding actions and outputs the hydraulic oil after work, which returns to the hydraulic pump assembly through the second circuit.

[0011] Furthermore, in the working state, the hydraulic pump assembly changes the output hydraulic oil pressure and flow by changing the swing angle, thereby controlling the parameters of the rotary operation.

[0012] Furthermore, in the braking state, the load torque of the output shaft of the power source is first reduced until it is dragged in the reverse direction, and the excess load is absorbed by the remaining load driven by the power source.

[0013] Furthermore, in the braking state, when the speed of the power source increases to a set value, the proportional valve opens to connect the first circuit and the second circuit.

[0014] Furthermore, a controller is provided for receiving a braking instruction and a rotation speed signal and a torque signal acquired by a sensor component, and sending a corresponding instruction to the proportional valve to change the opening size thereof.

[0015] A second aspect of the utility model provides a rotary system having a rotary load connected to a hydraulic pump assembly in the above-mentioned closed hydraulic system.

[0016] A second aspect of the utility model provides a traveling system having a traveling load connected to a hydraulic pump assembly in the above-mentioned closed hydraulic system.

[0017] Compared with the prior art, one or more of the above technical solutions have the following beneficial effects:

[0018] 1. Under braking, the load torque of the power source output shaft will first decrease until reverse dragging. During reverse dragging, the excess load is first absorbed by the remaining loads driven by the power source (such as the cooling system). When the excess load cannot be absorbed, the speed gradually increases. At this time, the oil circuit between the hydraulic pump assembly and the swing motor is connected through the proportional valve. The overflow effect of the proportional valve is used to dissipate the excess kinetic energy that causes the power source to overspeed, ensuring that the overspeed of the power source is controlled within the allowable range.

[0019] 2. The system makes very few structural changes to the original closed system. It only needs to add a proportional valve to connect the oil circuit between the hydraulic pump assembly and the rotary motor. The modification cost is low, and the control and debugging are simple. It can quickly solve the flying car phenomenon of the closed system braking and reduce the supporting debugging time. The sensors involved can use the existing sensors of the power source. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation on the present invention.

[0021] Figure 1 It is a structural schematic diagram of a slewing system with a closed hydraulic system provided by one or more embodiments of the utility model;

[0022] Figure 2 It is a structural schematic diagram of a walking system with a closed hydraulic system provided by one or more embodiments of the utility model;

[0023] Figure 3 It is a structural schematic diagram of an auxiliary valve group in a closed hydraulic system provided by one or more embodiments of the utility model.

[0024] In the figure: 1 power source, 2 hydraulic pump assembly, 3 hydraulic motor assembly, 4 rotary load (travel load), 5 sensor assembly, 6 electronically controlled proportional valve, 21 overflow valve, 22 oil replenishment valve, 23 oil replenishment circuit, 31 flushing valve group. DETAILED DESCRIPTION

[0025] The utility model is further described below in conjunction with the accompanying drawings and embodiments.

[0026] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0027] Terminology explanation:

[0028] The travel system is a device on large equipment such as construction machinery, agricultural machinery, and mining machinery that uses hydraulic energy as a driving force to drive the construction machinery to travel. It generally includes a hydraulic system and a connected travel load. For example: the forward and backward movement of a bulldozer.

[0029] The slewing system, also known as the slewing mechanism, is a device on large equipment such as construction machinery, agricultural machinery, and mining machinery. It uses hydraulic energy as power to drive the slewing load of the construction machinery to produce a slewing motion. For example, in a truck crane, the slewing mechanism drives the upper vehicle to slew, and under the condition of stable support of the lower vehicle, the truck crane can achieve a 360° operating range.

[0030] Open hydraulic system: The oil flows through the oil tank-pump-valve-motor-oil tank in sequence. Since the oil tank is openly connected to the outside of the circuit, it is called an open system.

[0031] Closed hydraulic system: The oil flows sequentially through the pump-motor-pump, and the main pipeline is not open to the external oil tank. Only a small amount of exchange is done through the flushing and oil replenishment circuit to achieve heat dissipation, hence the name closed system.

[0032] Pump control system: A hydraulic system that controls the speed of the actuator by controlling the displacement of the pump. Most closed hydraulic systems are pump control systems. Since it is a hydraulic pump, the displacement of the pump refers to the pressure and flow of the hydraulic oil output by the hydraulic pump. If it is a plunger hydraulic pump, the change of the pump displacement is generally achieved by changing the pump's swing angle. There are multiple plunger blocks on the rotor of a plunger hydraulic pump. When they come into contact with the swash plate, they push out the oil, generating pressure and flow. When the swash plate angle changes, the working stroke of the plunger will also change accordingly, thereby changing the output flow and pressure of the pump. The swash plate angle is called the pump's swing angle.

[0033] Valve controlled system: A hydraulic system that controls the speed of the actuator by controlling the opening of the valve. Most open systems are valve controlled systems.

[0034] It should be noted that the terms used here are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the utility model. As used here, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0035] As introduced in the background technology, the commonly used closed hydraulic system achieves braking by reverse drag, that is, using the kinetic energy of the load to drive the engine speed to increase. The greater the load's rotational inertia and the greater the rotation speed, the higher the load braking power peak, which can easily cause engine overspeed and runaway.

[0036] Therefore, the following embodiments provide a closed hydraulic system, a walking system and a slewing system, and add an electronically controlled proportional valve to connect the oil circuit between the hydraulic pump assembly and the slewing motor. During the period when the power source is reversed to achieve braking, the power that cannot be absorbed is dissipated through the overflow effect after the electronically controlled proportional valve is opened to dissipate the excess kinetic energy that causes the power source to overspeed, thereby quickly solving the power source overspeed and runaway problems caused by the closed hydraulic system braking.

[0037] Embodiment 1:

[0038] like Figure 1 As shown, the closed hydraulic system includes a power source 1, a hydraulic pump assembly 2, a hydraulic motor assembly 3, a sensor assembly 5, and an electronically controlled proportional valve 6.

[0039] Among them, the hydraulic pump assembly 2 is connected to the power source, the oil outlet of the hydraulic pump assembly 2 is connected to the oil inlet of the hydraulic motor assembly 3 through the first circuit, and the oil outlet of the hydraulic motor assembly 3 is connected to the oil inlet of the hydraulic pump assembly 2 through the second circuit; a third circuit is provided between the first circuit and the second circuit, and an electronically controlled proportional valve 6 is provided on the third circuit.

[0040] The hydraulic pump assembly 2 has conventional standard auxiliary components such as an overflow valve 21 , an oil replenishing valve 22 and an oil replenishing circuit 23 , and the hydraulic motor assembly 3 has a conventional standard auxiliary component of a flushing valve group 31 .

[0041] In this embodiment, Figure 3 As shown, the hydraulic pump assembly 2 has an oil replenishment circuit 23 connected between the first circuit and the second circuit, and an oil replenishment valve 22 is provided on the oil replenishment circuit 23; the hydraulic motor assembly 3 has a flushing circuit connected between the first circuit and the second circuit, and a flushing valve group 31 is provided on the flushing circuit. The auxiliary pipelines and valve groups such as the overflow valve 21, the oil replenishment valve 22, the oil replenishment circuit 23 and the flushing valve group 31 are all conventional auxiliary valve groups of the closed hydraulic system, and will not be described in detail in this embodiment.

[0042] The power source 1 may be an engine, whose output shaft drives the hydraulic pump assembly 2 to work. The hydraulic oil output by the hydraulic pump assembly 2 is connected to the hydraulic motor assembly 3 through two sets of oil circuits. The hydraulic motor assembly 3 is used to drive the load to produce corresponding actions.

[0043] The sensor assembly 5 includes a power source speed sensor and a torque sensor, which are used to obtain the speed and torque transmitted from the power source 1 to the hydraulic pump assembly 2 .

[0044] The two groups of oil circuits between the hydraulic pump assembly 2 and the hydraulic motor assembly 3 are connected through the electronically controlled proportional valve 6. The oil circuit can be a hydraulic hose.

[0045] The working method is:

[0046] Working stage: the power source 1 drives the hydraulic pump assembly 2 at a fixed speed. The hydraulic pump assembly 2 drives the hydraulic oil to be transmitted to the hydraulic motor assembly 3 through the hydraulic hose on one side by changing the swing angle. The output end of the hydraulic motor assembly 3 is used to connect the load. The oil flowing out of the other side of the hydraulic motor assembly 3 returns to the closed hydraulic pump 2 through the hydraulic hose and is sucked into the hydraulic pump assembly 2 to continue working.

[0047] Braking stage: When the driver receives the input signal to stop the load movement, the swing angle of the hydraulic pump assembly 2 will gradually decrease at a certain descending rate. At this time, the rotational kinetic energy generated by the inertia of the load itself drives the hydraulic motor assembly 3, and the hydraulic oil generated drives the hydraulic pump assembly 2 and drives the power source 1.

[0048] As the braking torque increases, the load torque of the power source output shaft will first decrease until it is dragged in the reverse direction. The excess load will first be absorbed by the remaining loads driven by the power source, such as the power source cooling system and the hydraulic cooling system, or by other loads working synchronously, such as the excavator's main pump.

[0049] When the remaining loads cannot fully absorb the power, the speed of the power source will begin to increase. The data collected by the speed sensor is used to determine whether the power source is overspeeding. When the speed reaches the warning value, the electronically controlled proportional valve 6 opens to connect the two sides of the rotary oil circuit. The overflow of the electronically controlled proportional valve 6 dissipates the excess kinetic energy that causes the power source to overspeed, ensuring that the power source overspeed is within the allowable range.

[0050] The rated flow and controllable pressure difference of the electronically controlled proportional valve 6 in the system can be selected according to the load and power source torque matching to ensure that the kinetic energy of load braking is completely dissipated through the overflow of the electronically controlled proportional valve 6 while ensuring that the power source does not overspeed.

[0051] The selection of the electronically controlled proportional valve 6 in the system is based on the following principles:

[0052] (1) On the basis of the rated pressure meeting the maximum working pressure of the system, a 20% pressure overshoot is added, which can cover the range requirement of 15% pressure overshoot in the relevant standard test of the relief valve.

[0053] (2) The rated flow rate must meet the system's maximum deceleration brake overflow flow limit. In practice, it must be determined based on the specific load type and the maximum braking flow rate. The maximum braking flow rate is the time it takes for the motor to decrease from the highest speed to zero speed, and the average is taken based on the braking time. Therefore, the smaller the maximum speed of the load and the smaller the moment of inertia, the smaller the rated flow rate.

[0054] When the load itself has a low speed, small rotational kinetic energy, and a light braking back-drag condition, the optimal braking speed can be achieved by controlling the pump without causing speed overshoot. At this time, the electronically controlled proportional valve 6 is closed, and the overall control is the same as the existing closed rotary system.

[0055] When the load itself has a high speed, large rotational kinetic energy, and severe braking back-drag, achieving the optimal braking speed by controlling the pump will cause speed overshoot and exceed the warning value. The electronically controlled proportional valve 6 opens, and the valve opening is proportional to the speed overshoot, dissipating the back-rotational kinetic energy through the valve port overflow.

[0056] The above system makes very little structural change to the original closed system. It only needs to add an electronically controlled proportional valve to connect the oil circuit between the hydraulic pump assembly and the hydraulic motor assembly. The sensor part can use the sensor on the existing power source. The modification cost is extremely low and the control and debugging are simple.

[0057] In some prior arts, such as CN106542448, a throttle valve is added to the oil circuit connecting the hydraulic pump assembly and the rotary motor, and two sets of pressure sensors are added before and after the throttle valve, and the obtained oil pressure signal is used to control the opening or closing of the throttle valve. The scheme is similar to the present embodiment in terms of technical principle, but it deals with the runaway suppression at the motor end, rather than the runaway suppression of the engine (power source) targeted by the present embodiment. The pressure signal used needs to be provided by an additional pressure sensor, and the hardware cost is higher.

[0058] Compared with the prior art CN106542448, this embodiment adopts an electronically controlled proportional valve instead of a throttle valve with a fixed throttling area. The valve opening size can be set according to the working conditions to achieve adaptation under different speeds and moments of inertia. The speed and torque signals required for different working conditions can be obtained by using the standard speed sensor and torque sensor on the power source (engine). On the one hand, the modification cost is extremely low, and the control and debugging are simple. It can quickly solve the flying car phenomenon of closed system braking and reduce the supporting debugging time. It can also accurately control the energy recovery part and the excess part to improve the energy saving effect.

[0059] In addition, this embodiment is mainly used to cope with two types of loads: large speed and small inertia (walking) and large inertia and small speed (rotation), and can be applied to the rotation system and the walking system.

[0060] Embodiment 2:

[0061] like Figure 1 As shown, a rotary system includes the hydraulic pump assembly 2 in the closed hydraulic system of embodiment 1 connected to the rotary load 4, which is used to quickly and cost-effectively suppress the load's reverse drag power source to avoid overspeed and runaway of the power source.

[0062] Embodiment three:

[0063] like Figure 2 As shown, a walking system includes the hydraulic pump assembly 2 in the closed hydraulic system of embodiment 1 connected to the walking load 4, which is used to quickly and cost-effectively suppress the load's reverse drag power source to avoid overspeeding and runaway of the power source.

[0064] The above description is only the preferred embodiment of the utility model, and is not intended to limit the utility model. For those skilled in the art, the utility model can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model shall be included in the protection scope of the utility model.

Claims

1. Closed hydraulic system, characterized in that: It includes a hydraulic pump assembly connected to a power source, the oil outlet of the hydraulic pump assembly is connected to the oil inlet of the hydraulic motor assembly through a first circuit, and the oil outlet of the hydraulic motor assembly is connected to the oil inlet of the hydraulic pump assembly through a second circuit; a third circuit is provided between the first circuit and the second circuit, and a proportional valve is provided on the third circuit.

2. The closed hydraulic system according to claim 1, characterized in that: The power source is provided with a sensor assembly, which includes a rotation speed sensor and a torque sensor, and is used to obtain a rotation speed signal and a torque signal transmitted from the power source to the hydraulic pump assembly.

3. The closed hydraulic system according to claim 1, characterized in that: The proportional valve is an electrically controlled proportional valve.

4. The closed hydraulic system according to claim 1, characterized in that: In the working state, the hydraulic pump assembly changes the output hydraulic oil pressure and flow by changing the swing angle, thereby controlling the parameters of the rotary operation.

5. The closed hydraulic system according to claim 1, characterized in that: In the braking state, when the speed of the power source increases to the set value, the proportional valve opens to connect the first circuit and the second circuit.

6. The closed hydraulic system according to claim 1, characterized in that: It also has a controller for receiving braking instructions and speed signals and torque signals acquired by the sensor assembly, and sending corresponding instructions to the proportional valve to change its opening size.

7. A rotary system, characterized in that: A closed hydraulic system as claimed in any one of claims 1 to 6, and a rotary load connected to a hydraulic pump assembly in the closed hydraulic system.

8. A walking system, characterized in that: A closed hydraulic system as claimed in any one of claims 1 to 6, and a traveling load connected to a hydraulic pump assembly in the closed hydraulic system.

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