CN113529843A - Pressure coupling hydraulic hybrid power driving loop, control method thereof and excavator - Google Patents
Pressure coupling hydraulic hybrid power driving loop, control method thereof and excavator Download PDFInfo
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- CN113529843A CN113529843A CN202010321320.2A CN202010321320A CN113529843A CN 113529843 A CN113529843 A CN 113529843A CN 202010321320 A CN202010321320 A CN 202010321320A CN 113529843 A CN113529843 A CN 113529843A
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
- E02F9/20—Drives; Control devices
- E02F9/22—Hydraulic or pneumatic drives
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
- E02F9/20—Drives; Control devices
- E02F9/22—Hydraulic or pneumatic drives
- E02F9/2264—Arrangements or adaptations of elements for hydraulic drives
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B1/00—Installations or systems with accumulators; Supply reservoir or sump assemblies
- F15B1/02—Installations or systems with accumulators
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B21/00—Common features of fluid actuator systems; Fluid-pressure actuator systems or details thereof, not covered by any other group of this subclass
- F15B21/14—Energy-recuperation means
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
- F15B2211/21—Systems with pressure sources other than pumps, e.g. with a pyrotechnical charge
- F15B2211/214—Systems with pressure sources other than pumps, e.g. with a pyrotechnical charge the pressure sources being hydrotransformers
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/60—Other road transportation technologies with climate change mitigation effect
- Y02T10/62—Hybrid vehicles
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Abstract
The invention discloses a pressure coupling hydraulic hybrid power driving circuit, a control method thereof and an excavator, wherein the pressure coupling hydraulic hybrid power driving circuit comprises a three-way pressure matcher, wherein a first external oil port of the three-way pressure matcher is connected with a first oil port of an actuating element; the second oil port of the three-way pressure matcher and the second external oil port of the actuating element are connected with the hydraulic pump and the oil tank through a control valve; and a third oil port of the three-way pressure matcher is connected with an oil port of the energy accumulator. The oil port pressure and the flow of the tee joint pressure matcher satisfy a pressure coupling relation: (PA 1 ±. Δ P) q1= P2 · q2+ PX · q3 and q1= q2+ q 3. By adjusting P2 and q2, the function of the accumulator as an auxiliary power source is realized without loss due to the change of the load pressure PA1 of the actuating element, and the problems that the pressure of a hydraulic pump, the load pressure of the actuating element and the pressure of hydraulic oil of the accumulator are difficult to match and the energy-saving operation is difficult in the prior art of hybrid power are solved.
Description
Technical Field
The invention relates to a hydraulic transmission technology, in particular to a pressure coupling hydraulic hybrid power driving circuit, a control method thereof and an excavator.
Background
In order to adapt to the working condition that the load on an actuating element changes between a positive interval and a negative interval, a hydraulic system with an energy recovery function generally adopts a hydraulic pump and an energy accumulator as a driving loop of a hybrid power source. When the load of the actuating element is negative, the load applies work to the actuating element, the hydraulic energy (pressure oil) output by the actuating element is stored in the accumulator, and the hydraulic pump is in an unloading or low-power running state. When the load of the actuating element is positive, the energy accumulator releases the stored hydraulic energy (pressure oil) and the pressure oil output by the hydraulic pump together to drive the actuating element to do work on the load; at the moment, although the hydraulic pump is in a high-power running state, the energy accumulator is used as an auxiliary power source, so that the driving power is saved, and the energy is saved. Therefore, the hydraulic hybrid power driving circuit of the hydraulic pump and the accumulator can be widely applied to engineering machinery, hoisting machinery and steel rolling equipment. At present, the technical problem restricting the popularization and application of the hydraulic hybrid power driving circuit is the pressure matching problem among the pressure of a hydraulic pump, the load pressure of an actuating element and the hydraulic oil pressure of an accumulator (hereinafter referred to as the accumulator oil pressure). The pressure of the hydraulic pump is determined by the minimum load pressure; the pressure of the actuator is determined by the external load; the accumulator oil pressure is determined by the change in charge pressure and gas volume, independent of the external load. This presents difficulties for pressure matching: (1) under the working condition of negative load, when the external load does work on the execution element, the pressure of the hydraulic oil output by the execution element is determined by the load, and if the pressure is smaller than the oil pressure of the energy accumulator, the pressure oil output by the execution element cannot enter the energy accumulator to be stored. (2) Under the positive load working condition, if the load pressure of the actuating element is not less than the oil pressure of the energy accumulator, the pressure oil stored by the energy accumulator can not be released, and the energy accumulator can not play a role of an auxiliary power source; when the load pressure of the actuating element is too much smaller than the oil pressure of the energy accumulator, the instant release of the pressure oil stored by the energy accumulator is generated, and the overflow is wasted after the pressure oil exceeds the requirement of the actuating element. (3) No matter under load working condition or under positive load working condition, as long as the change of the load pressure of the actuating element caused by the change of the external load reaches a certain limit, the normal process of collecting (storing) or releasing (releasing) the pressure oil of the energy accumulator is stopped, and the energy accumulator can not play a role of an auxiliary power source. (4) The problem is further compounded by the fact that the accumulator oil pressure may also change during the process of the accumulator receiving (storing) or releasing (releasing) oil (due to the change in accumulator charge volume).
The prior art has overcome the above difficulties in two ways. Firstly, the bearing area (or the motor displacement) of an execution element is optimally designed, and the inflation pressure and the initial volume of the energy accumulator are accurately calculated, so that the oil pressure of the energy accumulator is matched with the load pressure of the execution element (when the energy accumulator receives oil, the load pressure is always slightly greater than the oil pressure of the energy accumulator, and when the energy accumulator discharges oil, the load pressure is always slightly smaller than the oil pressure of the energy accumulator). Obviously, the difficulty of optimally designing the pressure-bearing area is great, because the design of the pressure-bearing area firstly needs to ensure that the requirement of load driving force and the requirement of load speed are met, and then the matching with the oil pressure of the energy accumulator can be considered. Meanwhile, the method is only suitable for the working condition with determined external load and small change, and is basically not suitable for engineering machinery. And secondly, a booster, a proportional pressure reducing valve or a pressure regulating valve group are arranged between the actuating element and the energy accumulator as well as the hydraulic pump, and the oil pressure at the outlet of the energy accumulator, the output pressure of the hydraulic pump and the output oil pressure of the actuating element during negative load are regulated in real time so as to realize basic pressure matching. The method is a main method adopted in the hydraulic hybrid power system of the engineering machinery at present. The method can generate larger overflow energy loss and throttling energy loss, and attenuate the energy-saving effect of using the energy accumulator as an auxiliary power source. Meanwhile, the system is complex, and the failure rate and the maintenance difficulty are increased.
Disclosure of Invention
The invention aims to solve the technical problem that the prior art is insufficient, and provides a pressure coupling hydraulic hybrid power driving loop, a control method thereof and an excavator, so that on-line matching of the pressure of a hydraulic pump, the load pressure of an execution element and the pressure of hydraulic oil of an energy accumulator is realized on the premise of not generating overflow energy loss and throttling energy loss, and the function of the energy accumulator as an auxiliary power source is ensured not to be lost due to load change.
In order to solve the technical problems, the invention adopts the technical scheme that: a pressure coupling hydraulic hybrid power driving loop comprises a three-way pressure adapter, wherein a first external oil port of the three-way pressure adapter is connected with a first oil port of an actuating element; the second oil port of the three-way pressure matcher and the second external oil port of the actuating element are connected with the hydraulic pump and the oil tank through a control valve; and a third oil port of the three-way pressure matcher is connected with an oil port of the energy accumulator.
By means of the structure, the three-way pressure matcher is arranged in the hydraulic loop, and the pressure and the flow of the three-way pressure matcher are adjusted, so that the on-line matching of the pressure of the hydraulic pump, the load pressure of the executing element and the hydraulic oil pressure of the energy accumulator can be realized, the function of the energy accumulator as an auxiliary power source is ensured not to be lost due to load change, the implementation is easy, the structure of the driving loop is simple, and the overflow energy loss and the throttling energy loss are not generated.
The three-way pressure matcher comprises a first energy conversion device and a second energy conversion device; the oil ports on one sides of the first energy conversion device and the second energy conversion device are communicated to form a first oil port of the three-way pressure matcher; the oil port on the other side of the first energy conversion device and the oil port on the other side of the second energy conversion device are respectively a second oil port and a third oil port of the three-way pressure matcher; the transmission shaft of the first energy conversion device is rigidly and coaxially connected with the transmission shaft of the second energy conversion device, and the movement directions of the first energy conversion device and the second energy conversion device are the same. The tee joint pressure matcher has the advantages of simple structure, easy realization, strong practicability, low failure rate and easy maintenance.
In the invention, for simple design, the first energy conversion device and the second energy conversion device can be hydraulic motors, and the two hydraulic motors have the same steering direction; the hydraulic motor can be in a motor working condition or a pump working condition; preferably, the hydraulic motor is one of a plunger motor, a gear motor and a vane motor; preferably, the plunger motor comprises a radial plunger motor and an axial plunger motor; the gear motor comprises an internal gear motor and an external gear motor; the vane motor includes a single-acting vane motor and a double-acting vane motor.
In order to realize the pressure and flow detection of the oil ports of the three-way pressure matcher, pressure detection devices are respectively arranged at the first oil port, the second oil port and the third oil port of the three-way pressure matcher.
In the invention, a pressure detection device (such as a pressure sensor), a hydraulic pump and a control valve are all electrically connected with a controller, the pressure detection device sends detected data to the controller, and the controller can adjust the discharge capacity of the hydraulic pump and the opening of the control valve according to pressure and flow values.
In the invention, three oil ports of the three-way pressure matcher meet the following mathematical models:
when hydraulic oil flows from the second oil port and the third oil port of the three-way pressure matcher to the first oil port of the three-way pressure matcher, (PA 1 +. DELTA.P) × (q 2+ q 3) = P2 · q2+ PX · q 3;
when hydraulic oil flows from the first oil port to the second oil port and the third oil port of the three-way pressure matcher, (PA 1-delta P) × (q 2+ q 3) = P2 · q2+ PX · q 3;
wherein q2 and q3 are respectively the flow of a second oil port and the flow of a third oil port of the three-way pressure matcher; delta P is the pressure loss of the inlet of the energy conversion device in the three-way pressure matcher; PA1 is the load pressure of the actuator positive load drive cavity or the negative load oil return cavity, PA1= P1, and P1 is the first oil port pressure of the three-way pressure matcher; PX is the pressure of an oil port of the accumulator, PX = P3, and P3 is the pressure of a third oil port of the three-way pressure matcher; and P2 is the pressure of the second oil port of the three-way pressure matcher.
Through the mathematical model, the pressure and the flow of the oil port of the three-way pressure matcher can be effectively adjusted.
In the invention, when the load pressure of the actuating element changes and/or the pressure of the oil inlet and the oil outlet of the energy accumulator fluctuates, the pressure and the flow of the second oil port of the three-way pressure matcher are adjusted, so that the pressure values of the three oil ports of the three-way pressure matcher are matched with the load pressure of the actuating element.
In the invention, the pressure and the flow of the second oil port of the three-way pressure matcher can be adjusted by controlling the discharge capacity of the hydraulic pump and the opening of the control valve, and the control is simple and easy to realize.
In order to further reduce the structural complexity, the control valve comprises a multi-way reversing valve; the pressure oil port of the multi-way reversing valve is connected with the outlet of the hydraulic pump; the oil return port of the multi-way reversing valve is connected with an oil tank; the first working oil port of the multi-way reversing valve is connected with the second oil port of the three-way pressure matcher; and the second working oil port of the multi-way reversing valve is connected with the second external oil port of the actuating element.
Correspondingly, the invention further provides an excavator, and the excavator is provided with the pressure coupling hydraulic hybrid power driving circuit.
As an inventive concept, the present invention further provides a control method of the above pressure-coupled hydraulic hybrid drive circuit, the method mainly comprising: and the pressure and the flow of a second oil port of the three-way pressure matcher are adjusted to realize the matching of the pressure values of the three oil ports of the three-way pressure matcher and the load pressure of the actuating element.
As shown in the foregoing, in order to make the control process simple and easy to implement, the pressure and the flow rate of the second oil port of the three-way pressure matcher may be adjusted by controlling the displacement of the hydraulic pump and the opening of the control valve.
In the control method, the pressure and the flow of the second oil port of the three-way pressure matcher can be efficiently adjusted by utilizing the following mathematical models:
when hydraulic oil flows from the second oil port and the third oil port of the three-way pressure matcher to the first oil port of the three-way pressure matcher, (PA 1 +. DELTA.P) × (q 2+ q 3) = P2 · q2+ PX · q 3;
when hydraulic oil flows from the first oil port to the second oil port and the third oil port of the three-way pressure matcher, (PA 1-delta P) × (q 2+ q 3) = P2 · q2+ PX · q 3;
wherein q2 and q3 are respectively the flow of a second oil port and the flow of a third oil port of the three-way pressure matcher; delta P is the pressure loss of the inlet of the energy conversion device in the three-way pressure matcher; PA1 is the load pressure of the actuator positive load drive cavity or the negative load oil return cavity, PA1= P1, and P1 is the first oil port pressure of the three-way pressure matcher; PX is the pressure of an oil port of the accumulator, PX = P3, and P3 is the pressure of a third oil port of the three-way pressure matcher; and P2 is the pressure of the second oil port of the three-way pressure matcher.
Compared with the prior art, the invention has the beneficial effects that:
1. the energy accumulator in the loop can not lose the function as an auxiliary power source due to the change of the load pressure of the executing element, can be effectively used for energy-saving operation when the executing element is loaded with positive and negative intervals to change working conditions, and solves the problem that the pressure of a hydraulic pump, the load pressure of the executing element and the pressure of hydraulic oil of the energy accumulator are difficult to match in the prior art;
2. the invention has simple structure, easy realization, low failure rate and easy maintenance;
3. the invention does not generate overflow energy loss and throttling energy loss, and has good energy-saving effect.
Drawings
FIG. 1 is a schematic structural diagram of a tee pressure adapter of the present invention;
FIG. 2 is a schematic diagram of a pressure-coupled hydraulic hybrid power driving circuit according to the present invention;
FIG. 3 is a schematic diagram of the three ports K1, K2 and K3 of the three-way pressure adapter of the present invention;
FIG. 4 is a schematic diagram of the drive circuit of the present invention for driving a hydraulic cylinder of a boom of a hydraulic excavator;
fig. 5 is a schematic view of a prior art drive circuit for a boom cylinder of a hydraulic excavator.
Detailed Description
The invention relates to a hydraulic driving circuit which takes a hydraulic pump as main power and an energy accumulator (an inflatable energy accumulator) as auxiliary power, in particular to a pressure coupling hydraulic hybrid driving circuit for short. The pressure coupling hydraulic hybrid power driving loop is used for energy-saving operation when an execution element is loaded with positive and negative interval change working conditions. When the actuator bears a negative load, the circuit can recover pressure energy generated by the negative load acting on the actuator, and when the actuator drives a positive load, the circuit can release the recovered pressure energy to be used as an auxiliary power source. In the invention, the actuating element can be a hydraulic cylinder or a hydraulic motor; the negative load may be an external force (including gravity) or an inertial force generated when the actuator brakes.
It should be noted that, in the present invention, the pressure coupling hydraulic hybrid power driving circuit includes, in addition to the variable hydraulic pump, the control valve (multi-way reversing valve or other related valves), the oil tank and the actuator of the conventional hydraulic system, a pneumatic accumulator used as an auxiliary power source, a three-way pressure adapter adopting a pressure coupling technology, a plurality of pressure sensors and a controller.
The inflatable accumulator can be of a leather bag type or a piston type; the gas to be inflated may be nitrogen or some inert gas (e.g. helium). The charging pressure of the gas-filled accumulator must be greater than the load pressure generated by the positive and negative loads in the working chamber of the actuator.
When the pressure coupling hydraulic hybrid power driving loop can apply work to the execution element by a negative load, pressure oil generated in an oil return cavity of the execution element is collected into the energy accumulator for storage. The procedure of storing the input is carried out smoothly even when the pressure of the return oil chamber of the actuator is lower than the charging pressure of the accumulator and is not influenced by the change of the load. The pressure coupling hydraulic hybrid power driving circuit can input pressure oil stored in the energy accumulator into the driving cavity of the actuating element when the actuating element drives an external load to be used as auxiliary power, so that energy is saved, and the process is not influenced by the pressure change of the energy accumulator. The reason why the pressure-coupled hydraulic hybrid drive circuit has the above-described function is that a three-way pressure adapter using a pressure coupling technique is provided.
The tee joint pressure matcher is formed by coupling a first energy conversion device and a second energy conversion device. The energy conversion device can input hydraulic energy through the oil port and output mechanical energy on the transmission shaft; mechanical energy can be input into the transmission shaft, and hydraulic energy can be output through the oil port. The energy transforming device may be some kind of hydraulic element, such as a hydraulic cylinder, a hydraulic pump, a hydraulic motor, etc. The hydraulic motor can be a plunger motor (including radial and axial), a gear motor (including inner and outer meshes) or a vane motor (including single-acting and double-acting); each motor can be in a motor working condition and can also be in a pump working condition. Although the following description will be given taking the example in which the energy conversion device is a hydraulic motor, the present invention is also applicable to a configuration in which the energy conversion device is another element.
In the embodiment of the invention, the three-way pressure matcher adopting the pressure coupling technology is formed by coupling two hydraulic motors (pumps). The coupling in the present invention includes: (1) the oil ports on one side of the two motors are communicated to form a common external oil port K1, and the oil ports K2 and K3 on the other side of each motor are respectively kept in independent external connection; (2) the transmission shafts of the two motors are in rigid coaxial connection, and the coaxial connection can be the coaxial connection of an internal spline shaft and an external spline shaft, the coaxial connection of a flat key of the shaft and a shaft sleeve, and other coaxial connection modes; (3) the two motors have the same rotation direction, but can rotate forwards or backwards; (4) three external oil ports of the two motors are connected, and as long as any one of the three external oil ports is plugged, the motors cannot rotate, namely other oil ports are also plugged; (5) the displacement of the two motors can be the same or different.
The hydraulic function symbol of the three-way pressure matcher formed by coupling two hydraulic motors (pumps) is shown in fig. 1. K1, K2 and K3 are external oil ports, wherein K1 is a common oil port.
The pressure coupling hydraulic hybrid power driving circuit comprising the three-way pressure matcher has the connection mode of all components as shown in fig. 2. In the figure, two external oil ports of the actuating element are A1 and B1; a1 is an oil return port when the actuator bears a negative load, and is also an oil inlet port when the actuator drives a positive load; b1 is the oil inlet when the actuator bears the negative load.
The pressure coupling hydraulic hybrid power driving circuit comprising the three-way pressure matcher has the connection mode of all components as shown in fig. 2. In the loop, two external oil ports of an actuating element are A1 and B1; a1 is an oil return port when the actuator bears a negative load, and is also an oil inlet port when the actuator drives a positive load; b1 is the oil inlet when the actuator bears the negative load.
The coupling modes of the components of the circuit include (but are not limited to) the following: (1) the pressure oil port P of the multi-way reversing valve is connected with the outlet of the variable hydraulic pump, the oil return port T of the multi-way reversing valve is connected with the oil tank, the working oil port B of the multi-way reversing valve is connected with the actuating element oil port B1 (a second external oil port), and the working oil port A is connected with the oil port K2 of the three-way pressure matcher; (2) the oil port K3 of the three-way pressure adapter is connected with the oil inlet and outlet X of the inflatable energy accumulator, and the oil port K1 of the three-way pressure adapter is connected with the oil port A1 (a first external oil port); (3) the pressure oil output by the variable hydraulic pump enters an actuating element port B1 through a port B of the multi-way directional valve under the control of the multi-way directional valve, or enters a three-way pressure matcher port K2 through a port A of the multi-way directional valve, or is unloaded through a port T of the multi-way directional valve; (4) pressure sensors PU1, PU2 and PU3 are arranged at three oil ports of the three-way pressure matcher, and the sensors (including but not limited to the three sensors) transmit online detection values to a controller for controlling the displacement of the variable hydraulic pump and the opening degree of the multi-way reversing valve by a pressure coupling algorithm.
In the connection mode shown in fig. 2, the working mode of the three-way pressure matcher is as follows: when the hydraulic oil flows to the ports K2 and K3 from the port K1, the motor (the left motor in the figure 2) with the port K2 is in the working condition of the motor, and the motor (the right motor in the figure 2) with the port K3 is in the working condition of the pump; when the hydraulic oil flows from the ports K2 and K3 to the port K1, the motor with the port K2 (the left motor in fig. 2) is in the pump operating mode, and the motor with the port K3 (the right motor in fig. 2) is in the motor operating mode.
Under the connection mode of the pressure coupling hydraulic hybrid power driving circuit, the working mode of the three-way pressure matcher is as follows: when the hydraulic oil flows to the ports K2 and K3 from the port K1, the motor (the left motor in the figure 2) with the port K2 is in the working condition of the motor, and the motor (the right motor in the figure 2) with the port K3 is in the working condition of the pump; when the hydraulic oil flows from the ports K2 and K3 to the port K1, the motor with the port K2 (the left motor in fig. 2) is in the pump operating mode, and the motor with the port K3 (the right motor in fig. 2) is in the motor operating mode.
While the circuit of fig. 2 may be supplemented with hydraulic components and lines for certain purposes, it is within the scope of the present invention to provide the basic features described above.
When the three-way pressure matcher operates, the mechanical power on the two motor transmission shafts is ensured to be equal due to the coaxial connection of the two motor transmission shafts. Thus, ignoring friction and internal leakage losses: the hydraulic power difference between the inlet and the outlet of the two motors is also equal. The pressure and the flow at three oil ports K1, K2 and K3 of the three-way pressure matcher are respectively as follows: p1, q1, P2, q2, P3, q 3. As shown in fig. 3. Then there are: p1 · q 2-P2 · q2= P3 · q 3-P1 · q 3; namely: p1 (q 2+ q 3) = P2 · q2+ P3 · q 3.
The principle of flow continuity is known as follows: q1= q2+ q3 (1)
The hydraulic power relationship is therefore: p1 · q1= P2 · q2+ P3 · q3 (2)
Considering friction and internal leakage losses, there is a loss of hydraulic power, both expressed as a pressure loss Δ P at the motor inlet. The value of Δ P varies depending on the type of motor and the viscosity of hydraulic oil, and can be measured by tests, usually about 0.5 Mpa. The hydraulic power relation at this time is:
（P1±△P）q1= P2·q2+ P3·q3 （3）
consider the modes of coupling of the circuit as: p1 = PA1, P3= PX, where PA1 is the load pressure of the actuator positive load drive chamber (negative load return chamber) and PX is the charge accumulator inlet and outlet oil pressure.
The following can be obtained: (PA 1 ±. Δ P) q1= P2 · q2+ PX · q3 (4)
When the hydraulic oil flows to K1 from K2 and K3 ports, the + number is taken; when the hydraulic oil flows from the port K1 to the ports K2 and K3, the hydraulic oil takes the sign-one.
And (4) combining the formulas (1) and (4) to obtain a mathematical model of the pressure coupling algorithm in the loop.
According to the mathematical model of the pressure coupling algorithm, when the load pressure PA1 of the actuating element is changed or the pressure PX of the oil inlet and the oil outlet of the energy accumulator is fluctuated in the field working condition, the pressure coupling hydraulic hybrid power driving circuit can ensure the stability of the function of storing and releasing the pressure oil of the energy accumulator through the adjustment of the P2 value and the q2 value, and is used for energy-saving operation (namely ensuring the stability of the function of storing and releasing the pressure oil of the energy accumulator) when the working condition of changing the positive and negative intervals of the load of the actuating element is changed. Namely: when the negative load applies work to the execution element, the pressure coupling hydraulic hybrid power driving circuit can collect pressure oil generated in an oil return cavity of the execution element into the energy accumulator for storage; the procedure of storing the input is carried out smoothly even when the pressure of the return oil chamber of the actuator is lower than the charging pressure of the accumulator and is not influenced by the change of the load. When the executing element drives a positive external load, the pressure coupling hydraulic hybrid power driving circuit can input pressure oil stored in the energy accumulator into the executing element driving cavity to be used as auxiliary power, energy saving is achieved, and the process is not affected by pressure change of the energy accumulator. And the adjustment of the P2 value and the q2 value can be controlled by the displacement of the variable displacement hydraulic pump and the opening degree of the multi-way reversing valve. The discharge capacity of the variable hydraulic pump and the opening of the multi-way reversing valve are reasonably adjusted through a pressure coupling algorithm, the matching of three oil port pressure values of the three-way pressure matcher and the load pressure PA1 of the actuating element is realized, the function of the inflatable accumulator serving as an auxiliary power source in the loop is ensured not to be lost due to the change of the load pressure of the actuating element, and the energy-saving operation can be effectively used for energy-saving operation when the load of the actuating element has positive and negative interval change working conditions.
Examples
The practical application system of the pressure coupling hydraulic hybrid power driving circuit for driving the hydraulic excavator boom hydraulic cylinder is shown in fig. 4. The pressure coupling hydraulic hybrid power driving circuit of the hydraulic excavator boom hydraulic cylinder comprises a boom cylinder bearing a gravity load, a three-way pressure matcher, an inflatable accumulator, a multi-way valve boom linkage, a variable hydraulic pump, a plurality of pressure sensors (P1, P2, P3, PA1 and PB 1) and a controller. The oil port K1 of the three-way pressure matcher is connected with an oil port A1 of a rodless cavity of a boom cylinder, the oil port K2 is connected with a working oil port A of a boom linkage of the multi-way valve, the oil port K3 is connected with an oil inlet and an oil outlet X of the inflatable energy accumulator, an oil port B1 of a rod cavity of the boom cylinder is connected with a working oil port B of the boom linkage of the multi-way valve, and a variable hydraulic pump is connected with an oil port P of the multi-way valve. The pilot oil for the multi-way valve boom train is pa7 and pb7, respectively.
In the actual working condition of the hydraulic excavator, the boom cylinder bears the weight of the whole boom and bucket (including cargos) of the hydraulic excavator, and the weight is converted into the force G on the piston rod end of the boom cylinder. When a movable arm of the hydraulic excavator descends and a piston rod of a movable arm cylinder retracts, G is a negative load; when the movable arm of the hydraulic excavator rises and the piston rod of the movable arm cylinder extends, G is a positive load. When a1 is the boom cylinder rodless chamber pressure-receiving area and B1 is the boom cylinder rod chamber pressure-receiving area, the boom cylinder rodless chamber oil pressure PA1= (G + PB1 · B1)/a1 is applied regardless of whether the boom is raised or lowered. In the formula, PB1 represents a boom cylinder rod chamber oil pressure. In FIG. 4, the hydraulic pressure PX of the accumulator should be about 5-10 MPa greater than PA 1.
When the pilot control oil pb7 of the multi-way valve boom linkage is activated, the multi-way valve boom linkage is in the left position, and the pressure oil output by the variable displacement hydraulic pump passes through the boom linkage B port to the boom cylinder rod chamber oil port B1. And the negative load G drives the piston rod of the movable arm cylinder to retract, and the return oil of the rodless cavity of the movable arm cylinder passes through an oil port A1 to a port K1 of the three-way pressure matcher. The oil return pressure is PA1, and the oil return flow rate is q 1. q1 enters a three-way pressure matcher and then is divided into two paths, and the flow q2 flows out of a K2 port of a left motor and returns to a tank after reaching a movable arm linkage A port of the multi-way valve. The flow q3 passes through the right motor and out of the K3 port, and enters the accumulator for storage. In this condition, the left motor inlet pressure P1 is PA1, the outlet pressure P2 is approximately 0, the motor condition is represented, the hydraulic power input is PA1 · q2, and the mechanical power output is used to drive the right motor. At this time, the right motor is in pump mode, inputting the mechanical power provided by the left motor, for raising the inlet pressure PA1 to P3= PX; the hydraulic power output by the right motor is (PX-PA1) · q 3. The hydraulic power of the internal leakage and the friction loss of the tee joint pressure matcher is expressed as pressure loss delta P, and the hydraulic power has the following characteristics according to the law of energy conservation:
PA1·q2-△P·q1=(PX-PA1)·q3
i.e. PA1 (q 2+ q 3) -. delta.p.q 1= px.q 3 (5)
According to the flow continuity equation: q1= q2+ q3 (6)
(5) Formula (ii) can be rewritten as: PA1 · q1- Δ P · q1= PX (q 1-q 2) (7)
The q1 value is determined by the descending speed of the movable arm of the excavator, the working condition cannot be changed freely after being determined, and the q2 value is determined by the displacement of the variable displacement pump and can be used as an adjusting parameter to be controlled by the controller according to the formulas (6) and (7). For a certain PA1 value and PX value, a suitable q2 value can always be found, making equation (7) true, even when PX is greater than PA1, the q2 value can be found. (6) And the expression (7) is a mathematical model of a pressure coupling algorithm of the descending working condition of the movable arm of the hydraulic excavator.
When the pilot control oil PA7 of the multi-way valve boom linkage acts, the multi-way valve boom linkage is at the right position, the pressure oil output by the variable hydraulic pump flows to the port K2 of the three-way pressure matcher through the port A of the boom linkage, the pressure oil stored in the accumulator flows into the right motor through the port K2 of the three-way pressure matcher, and the outlet pressure of the right motor is PA 1. At this time, the right motor is in a motor working condition, the input hydraulic power is (PX-PA1) · q3, the output mechanical power drives the left motor, the oil inlet pressure of a K2 port is increased from P2 to PA1, and the left motor is in a pump working condition. The energy conservation law and the flow continuity equation can be obtained by the same principle:
(PA1- P2)·q2+△P·q1=(PX-PA1)·q3
PA1·q1-P2·q2+△P·q1= PX（q1- q2） （8）
(6) and the expression (8) is a mathematical model of a pressure coupling algorithm of the lifting working condition of the movable arm of the hydraulic excavator. The controller adjusts P2 or q2 according to formulas (6) and (8), so that matching of determined PA1 and PX can be achieved.
In general, a drive circuit to which a boom cylinder of a hydraulic excavator is now applied is shown in fig. 5. The pressure coupling hydraulic hybrid power driving circuit is used for driving a movable arm hydraulic cylinder of a hydraulic excavator, so that the energy consumption of a hydraulic pump can be obviously reduced compared with the conventional circuit shown in figure 5, and the energy conservation is realized. The ascending and descending strokes of the movable arm hydraulic cylinder are all L, and the time is all t.
In the boom descending condition, the pressure PB1 of the rod cavity of the boom hydraulic cylinder is small in both circuits, the pressure PA1 of the rodless cavity of the boom hydraulic cylinder is used for balancing gravity G, PA1= G/A1, and A1 is the pressure-bearing area of the rodless cavity. At the moment, the output pressure of the hydraulic pump is 3-5Mpa, and the energy consumption of the two loops is basically the same. The difference is that: in the existing loop, return oil with the pressure of a rodless cavity of a movable arm hydraulic cylinder being PA1 returns to an oil tank through a multi-way valve, and pressure energy is changed into heat energy and is wasted. In the loop of the invention, after the return oil with the pressure of the rodless cavity of the movable arm hydraulic cylinder being PA1 passes through the three-way pressure matcher, the pressure oil with the flow rate being q2 drives the left motor to do work on the right motor, so that the oil pressure with the flow rate being q3 is increased to PX from PA1 and is stored in the energy accumulator. Therefore, in the boom-down condition and pressure coupling hydraulic hybrid driving circuit, the pressure of the rodless cavity of the boom hydraulic cylinder is the return oil of PA1, the pressure energy is recovered and stored without being wasted as heat energy like the conventional circuit, and the theoretical value of the recovered pressure energy is Wx = (PX-PA1) · q3 · t.
In the boom-up condition, the boom cylinder rodless chamber pressure in both circuits is PA1, and the flow rate qA entering the rodless chamber in the conventional circuit shown in fig. 5 is also the same as the flow rate q1 in the circuit of the present invention. That is, the hydraulic energy Wi entering the boom cylinder rodless chamber is substantially equal in both circuits, and Wi = (G/a 1) · q1 · t = PA1 · q1 · t. However, in the prior art circuit shown in FIG. 5, Wi is provided entirely by the hydraulic pump; in the circuit of the invention, Wi is provided by a hydraulic pump and an accumulator as auxiliary power. If energy loss of the three-way pressure matcher is neglected, the accumulator can provide all the recovered and stored hydraulic energy Wx = (PX-PA1) · q3 · t to the boom hydraulic cylinder rodless cavity when the boom descends, and at this time, the hydraulic pump only needs to provide hydraulic energy (Wi-Wx). Therefore, theoretically, the pressure coupling hydraulic hybrid drive circuit of the invention can save the energy consumption Wx = (PX-PA1) · q3 · t of the hydraulic pump in one working cycle of the boom descending and ascending. For a 35-ton hydraulic excavator, Wx is about 180-.
Although the circuit shown in fig. 4 may be added with hydraulic components and pipelines as required, or may have other forms of excavator hydraulic system combinations, and may be used for driving other actuators of an excavator, as long as the basic features of the pressure coupling hydraulic hybrid power driving circuit of the present invention (a three-way pressure matcher formed by coupling two energy conversion devices, a connection mode of three oil ports of the pressure matcher in the circuit, a mathematical model of a pressure coupling algorithm, and a control method) are provided, the present invention belongs to the implementation and application, and is within the protection scope of the present invention.
Claims (10)
1. A pressure coupling hydraulic hybrid power driving loop is characterized by comprising a three-way pressure matcher, wherein a first external oil port of the three-way pressure matcher is connected with a first oil port of an actuating element; the second oil port of the three-way pressure matcher and the second external oil port of the actuating element are connected with the hydraulic pump and the oil tank through a control valve; the third oil port of the three-way pressure matcher is connected with an oil port of an energy accumulator; preferably, the three-way pressure matcher comprises a first energy conversion device and a second energy conversion device; the oil ports on one sides of the first energy conversion device and the second energy conversion device are communicated to form a first oil port of the three-way pressure matcher; the oil port on the other side of the first energy conversion device and the oil port on the other side of the second energy conversion device are respectively a second oil port and a third oil port of the three-way pressure matcher; the transmission shaft of the first energy conversion device is rigidly and coaxially connected with the transmission shaft of the second energy conversion device, and the movement directions of the first energy conversion device and the second energy conversion device are the same.
2. The pressure coupled hydraulic hybrid drive circuit of claim 1, wherein the first energy conversion device and the second energy conversion device are both hydraulic motors, and the hydraulic motors are steered in the same direction; preferably, the hydraulic motor is in a motor condition or a pump condition; preferably, the hydraulic motor is one of a plunger motor, a gear motor and a vane motor; preferably, the plunger motor comprises a radial plunger motor and an axial plunger motor; the gear motor comprises an internal gear motor and an external gear motor; the vane motor includes a single-acting vane motor and a double-acting vane motor.
3. The pressure-coupled hydraulic hybrid driving circuit according to claim 1, wherein pressure detection devices are mounted at a first oil port, a second oil port and a third oil port of the three-way pressure matcher; preferably, all the pressure detection device, the hydraulic pump and the control valve are electrically connected with the controller.
4. The pressure-coupled hydraulic hybrid driving circuit of claim 1, wherein the three oil ports of the three-way pressure matcher satisfy the following mathematical models:
when hydraulic oil flows from the second oil port and the third oil port of the three-way pressure matcher to the first oil port of the three-way pressure matcher, (PA 1 +. DELTA.P) × (q 2+ q 3) = P2 · q2+ PX · q 3;
when hydraulic oil flows from the first oil port to the second oil port and the third oil port of the three-way pressure matcher, (PA 1-delta P) × (q 2+ q 3) = P2 · q2+ PX · q 3;
wherein q2 and q3 are respectively the flow of a second oil port and the flow of a third oil port of the three-way pressure matcher; delta P is the pressure loss of the inlet of the energy conversion device in the three-way pressure matcher; PA1 is the load pressure of the actuator positive load drive cavity or the negative load oil return cavity, PA1= P1, and P1 is the first oil port pressure of the three-way pressure matcher; PX is the pressure of an oil port of the accumulator, PX = P3, and P3 is the pressure of a third oil port of the three-way pressure matcher; and P2 is the pressure of the second oil port of the three-way pressure matcher.
5. The pressure-coupled hydraulic hybrid driving circuit as claimed in any one of claims 1 to 4, wherein when the load pressure of the actuator changes and/or the pressure of the oil in and out of the accumulator fluctuates, the pressure and flow rate of the second oil port of the three-way pressure matcher are adjusted to match the pressure values of the three oil ports of the three-way pressure matcher with the load pressure of the actuator.
6. The pressure-coupled hydraulic hybrid driving circuit as claimed in claim 5, wherein the pressure and flow rate of the second port of the three-way pressure matcher are adjusted by controlling the displacement of the hydraulic pump and the opening degree of a control valve.
7. The pressure coupled hydraulic hybrid drive circuit of claim 1, wherein the control valve comprises a multi-way reversing valve; the pressure oil port of the multi-way reversing valve is connected with the outlet of the hydraulic pump; the oil return port of the multi-way reversing valve is connected with an oil tank; the first working oil port of the multi-way reversing valve is connected with the second oil port of the three-way pressure matcher; and the second working oil port of the multi-way reversing valve is connected with the second external oil port of the actuating element.
8. An excavator, characterized in that the excavator employs the pressure-coupled hydraulic hybrid drive circuit as claimed in any one of claims 1 to 7.
9. A control method for a pressure coupled hydraulic hybrid drive circuit as claimed in any one of claims 1 to 7, the method mainly comprising: the pressure and the flow of a second oil port of the three-way pressure matcher are adjusted to realize the matching of the pressure values of the three oil ports of the three-way pressure matcher and the load pressure of the actuating element; preferably, the pressure and the flow of the second oil port of the three-way pressure matcher are adjusted by controlling the displacement of the hydraulic pump and the opening of the control valve.
10. The control method according to claim 9, wherein the pressure and flow of the second port of the three-way pressure matcher are adjusted by using the following mathematical model:
when hydraulic oil flows from the second oil port and the third oil port of the three-way pressure matcher to the first oil port of the three-way pressure matcher, (PA 1 +. DELTA.P) × (q 2+ q 3) = P2 · q2+ PX · q 3;
when hydraulic oil flows from the first oil port to the second oil port and the third oil port of the three-way pressure matcher, (PA 1-delta P) × (q 2+ q 3) = P2 · q2+ PX · q 3;
wherein q2 and q3 are respectively the flow of a second oil port and the flow of a third oil port of the three-way pressure matcher; delta P is the pressure loss of the inlet of the energy conversion device in the three-way pressure matcher; PA1 is the load pressure of the actuator positive load drive cavity or the negative load oil return cavity, PA1= P1, and P1 is the first oil port pressure of the three-way pressure matcher; PX is the pressure of an oil port of the accumulator, PX = P3, and P3 is the pressure of a third oil port of the three-way pressure matcher; and P2 is the pressure of the second oil port of the three-way pressure matcher.
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| CN202010321320.2A CN113529843B (en) | 2020-04-22 | 2020-04-22 | Pressure coupling hydraulic hybrid power driving circuit, control method thereof and excavator |
| PCT/CN2020/111986 WO2021212714A1 (en) | 2020-04-22 | 2020-08-28 | Pressure coupling hydraulic hybrid power driving circuit and control method therefor, and excavator |
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