CN113529843B - Pressure coupling hydraulic hybrid power driving circuit, control method thereof and excavator - Google Patents
Pressure coupling hydraulic hybrid power driving circuit, control method thereof and excavator Download PDFInfo
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- CN113529843B CN113529843B CN202010321320.2A CN202010321320A CN113529843B CN 113529843 B CN113529843 B CN 113529843B CN 202010321320 A CN202010321320 A CN 202010321320A CN 113529843 B CN113529843 B CN 113529843B
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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, and a first external oil port of the three-way pressure matcher is connected with a first oil port of an executing element; the second oil port of the three-way pressure matcher and the second outer oil port of the actuating element are connected with the hydraulic pump and the oil tank through the control valve; and a third oil port of the three-way pressure matcher is connected with an oil port of the energy accumulator. The pressure and the flow of the oil port of the three-way pressure matcher meet the pressure coupling relation: (PA 1 ±Δp) q1=p2·q2+px·q3 and q1=q2+q3. By adjusting P2 and q2, the function of the energy accumulator serving as an auxiliary power source can not be lost due to the change of load pressure PA1 of the actuating element, and the problems that in the prior art of hybrid power, the hydraulic pump pressure, the load pressure of the actuating element and the hydraulic oil pressure of the energy accumulator are difficult to match and energy-saving operation is difficult 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 applied to the executing element changes in the positive and negative intervals, 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 actuator is negative, the load applies work to the actuator, and the hydraulic energy (pressure oil) output by the actuator is stored in the accumulator, so that the hydraulic pump is in an unloading or low-power running state. When the load of the executing 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 executing element to do work on the load; at this time, the hydraulic pump is in a high-power running state, but the energy accumulator is used as an auxiliary power source, so that the driving power is saved, and the energy conservation is realized. Therefore, the hydraulic hybrid power driving circuit of the hydraulic pump and the energy accumulator can be widely applied to engineering machinery, lifting machinery and steel rolling equipment. At present, the technical problem that restricts the popularization and application of the hydraulic hybrid power driving circuit is the problem of pressure matching among the hydraulic pump pressure, the load pressure of an executing 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 in pressure matching: (1) When the external load does work on the executive component under the negative load working condition, the pressure of hydraulic oil output by the executive component 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 executive component cannot enter the energy accumulator at all for storage. (2) When the load is in the positive load working condition, if the load pressure of the executing element is not less than the oil pressure of the energy accumulator, the pressure oil stored in the energy accumulator cannot be released, and the auxiliary power source cannot be used; when the load pressure of the executing 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 waste after the load pressure exceeds the requirement of the executing element. (3) No matter the load working condition or the load working condition, as long as the load pressure change of the executing element caused by the external load change reaches a certain limit, the normal pressure oil collecting (storing) or releasing (releasing) process of the energy accumulator is stopped, and the auxiliary power source cannot be acted. (4) The problem is further compounded if it is considered that the accumulator oil pressure also changes during the accumulator's retraction (storage) or release (release) of oil (due to the change in accumulator charge volume).
There are two methods of overcoming the above difficulties in the prior art. Firstly, the bearing area (or motor displacement) of the executing 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 executing element (when the energy accumulator receives oil, the load pressure is always slightly larger 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 bearing area is great, because the bearing area is designed to ensure that the requirements of the load driving force and the 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 working conditions with determined external load and small change, and is basically not suitable for engineering machinery. And secondly, arranging a booster, a proportional pressure reducing valve or a pressure regulating valve group between the executing element and the accumulator as well as between the executing element and the hydraulic pump, and regulating the outlet oil pressure of the accumulator, the output pressure of the hydraulic pump and the output oil pressure of the executing element in real time when in negative load so as to realize basic pressure matching. This is the 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 the energy accumulator serving as an auxiliary power source. Meanwhile, the system is complicated, and the failure rate and the overhaul difficulty are increased.
Disclosure of Invention
The invention aims to solve the technical problems of overcoming the defects of the prior art and provides a pressure coupling hydraulic hybrid power driving circuit, a control method thereof and an excavator, and on the premise of not generating overflow energy loss and throttling energy loss, the on-line matching of hydraulic pump pressure, executive component load pressure and accumulator hydraulic oil pressure is realized, and the function of the accumulator serving 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 following technical scheme: 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 executing element; the second oil port of the three-way pressure matcher and the second outer oil port of the actuating element are connected with the hydraulic pump and the oil tank through the 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 circuit, the online matching of the hydraulic pump pressure, the load pressure of the actuating element and the hydraulic oil pressure of the energy accumulator can be realized by adjusting the pressure and the flow of the three-way pressure matcher, the function of the energy accumulator as an auxiliary power source is ensured not to be lost due to load change, the realization is easy, the driving circuit is simple in structure, and overflow energy loss and throttling energy loss cannot be generated.
The three-way pressure matcher comprises a first energy conversion device and a second energy conversion device; the oil ports at one side 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 three-way pressure matcher has the advantages of simple structure, easy realization, strong practicability, low failure rate and easy maintenance.
In the invention, for simplicity of design, the first energy conversion device and the second energy conversion device may 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 includes a radial plunger motor and an axial plunger motor; the gear motor comprises an inner meshing gear motor and an outer meshing gear motor; the vane motor includes a single-acting vane motor and a double-acting vane motor.
In order to realize pressure and flow detection of the oil ports of the three-way pressure matcher, the first oil port, the second oil port and the third oil port of the three-way pressure matcher are provided with pressure detection devices.
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 displacement of the hydraulic pump and the opening of the control valve according to the pressure and flow values.
In the invention, the three oil ports of the three-way pressure matcher meet 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 > = P < 2 >. Q < 2+ > 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) x (q2+q3) =P2.q2+PX.q3;
q2 and q3 are respectively the second oil port flow and the third oil port flow of the three-way pressure matcher; ΔP is the pressure loss at the inlet of the energy conversion device in the three-way pressure matcher; PA1 is the load pressure of the positive load driving cavity or the negative load oil return cavity of the executing element, PA1 = P1, and P1 is the pressure of the first oil port of the three-way pressure matcher; PX is the accumulator port pressure, px=p3, and P3 is the third port pressure of the three-way pressure matcher; and P2 is the pressure of a 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 regulated.
In the invention, when the load pressure of the executing element changes and/or the oil inlet and outlet pressure of the accumulator fluctuates, the pressure and the flow of the second oil port of the three-way pressure matcher are adjusted, so that the matching of the pressure values of the three oil ports of the three-way pressure matcher and the load pressure of the executing element is realized.
According to the invention, the pressure and the flow of the second oil port of the three-way pressure matcher can be regulated by controlling the displacement 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 of the invention 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 a second working oil port of the multi-way reversing valve is connected with a second external oil port of the executing element.
Correspondingly, the invention also provides the excavator, and the pressure coupling hydraulic hybrid power driving circuit of the excavator is provided.
As an inventive concept, the present invention also provides a control method of the above-mentioned pressure coupling hydraulic hybrid power driving circuit, which mainly includes: and the matching of the pressure values of the three oil ports of the three-way pressure matcher and the load pressure of the executing element is realized by adjusting the pressure and the flow of the second oil port of the three-way pressure matcher.
As shown before, in order to make the control process simple and easy to implement, the pressure and flow of the second oil port of the three-way pressure matcher can be adjusted by controlling the displacement of the hydraulic pump and the opening of the control valve.
In the control method, the pressure and flow of the second oil port of the three-way pressure matcher can be efficiently regulated 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 > = P < 2 >. Q < 2+ > 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) x (q2+q3) =P2.q2+PX.q3;
q2 and q3 are respectively the second oil port flow and the third oil port flow of the three-way pressure matcher; ΔP is the pressure loss at the inlet of the energy conversion device in the three-way pressure matcher; PA1 is the load pressure of the positive load driving cavity or the negative load oil return cavity of the executing element, PA1 = P1, and P1 is the pressure of the first oil port of the three-way pressure matcher; PX is the accumulator port pressure, px=p3, and P3 is the third port pressure of the three-way pressure matcher; and P2 is the pressure of a second oil port of the three-way pressure matcher.
Compared with the prior art, the invention has the following beneficial effects:
1. the function of the energy accumulator serving as an auxiliary power source in the loop is not lost due to the change of the load pressure of the executive component, the energy-saving operation can be effectively realized when the executive component is loaded with the working condition of positive and negative interval conversion, and the problem that the hydraulic pump pressure, the load pressure of the executive component and the hydraulic oil pressure of the energy accumulator are difficult to match in the prior art is solved;
2. the invention has simple structure, easy realization, low failure rate and easy maintenance;
3. the invention can not generate overflow energy loss and throttling energy loss, and has good energy-saving effect.
Drawings
FIG. 1 is a schematic diagram of a three-way pressure matcher of the present invention;
FIG. 2 is a schematic diagram of a pressure-coupled hydraulic hybrid drive circuit according to the present invention;
FIG. 3 is a schematic diagram of the pressure and the flow rate at three ports K1, K2, K3 of the three-way pressure matcher of the present invention;
FIG. 4 is a schematic illustration of a drive circuit of the present invention for driving a hydraulic cylinder of a hydraulic excavator boom;
fig. 5 is a schematic diagram of a prior art drive circuit for a hydraulic excavator boom cylinder.
Detailed Description
The invention takes a hydraulic pump as a main power, and an accumulator (an inflatable accumulator) as an auxiliary power. The pressure coupling hydraulic hybrid power driving loop is used for energy-saving operation when the executive component is loaded with the working condition of positive and negative interval conversion. When the executive component bears the negative load, the loop can recover the pressure energy generated by the work of the negative load on the executive component, and when the executive component drives the positive load, the loop can release the recovered pressure energy to be used as an auxiliary power source. In the invention, the executing 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-coupled hydraulic hybrid power driving circuit is specifically configured with an inflatable accumulator serving as an auxiliary power source, a three-way pressure matcher employing a pressure coupling technique, a plurality of pressure sensors, and a controller, in addition to a variable hydraulic pump, a control valve (a multiple directional valve or other related valve), an oil tank, and an actuator of a conventional hydraulic system.
The inflatable energy accumulator can be of a leather bag type or a piston type; the gas may be nitrogen or some inert gas (e.g., helium). The charge pressure of the pneumatic accumulator must be greater than the load pressure generated by the positive and negative loads in the actuator working chamber.
The pressure coupling hydraulic hybrid power driving circuit can store pressure oil generated in the oil return cavity of the executive component into the energy accumulator when the negative load does work on the executive component. The storage process can be smoothly performed even when the pressure of the oil return cavity of the actuating element is lower than the charging pressure of the accumulator, and is not influenced by load change. The pressure coupling hydraulic hybrid power driving circuit can input the pressure oil stored in the energy accumulator into the driving cavity of the executing element to be used as auxiliary power when the executing element drives an external load, so that energy saving is realized, and the process is not influenced by pressure change of the energy accumulator. The reason why the pressure-coupled hydraulic hybrid drive circuit has the above-described function is because a three-way pressure matcher employing a pressure coupling technique is provided.
The three-way 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 on the transmission shaft, and hydraulic energy can be output through the oil port. The energy transforming device may be a hydraulic element of some kind, such as a hydraulic cylinder, a hydraulic pump, a hydraulic motor, etc. The hydraulic motor may be a plunger motor (including radial and axial) or a gear motor (including internal and external engagement) or a vane motor (including single-acting and double-acting); each motor can be in a motor working condition or a pump working condition. The following description will take the case where the energy conversion device is a hydraulic motor as an example, but 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 and independently externally connected; (2) The transmission shafts of the two motors are connected in a rigid coaxial way, and the coaxial connection can be the coaxial connection of an internal spline shaft and an external spline shaft, the coaxial connection of a shaft and a flat key of a shaft sleeve, and other coaxial connection modes; (3) The two motors have the same steering direction, but can rotate forward and reverse; (4) The three external oil ports of the two motors are only required to plug any one of the oil ports, the motors can not rotate, and the two motors are equivalent to other oil ports which are also plugged; (5) The displacement of the two motors may 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 public oil port.
The coupling mode of each component part of the pressure coupling hydraulic hybrid power driving circuit comprising the three-way pressure matcher is shown in fig. 2. In the figure, two external oil ports of the execution element are A1 and B1; a1 is an oil return port when the executive component bears a negative load and is also an oil inlet for the executive component to drive a positive load; b1 is an oil inlet when the executive component bears a negative load.
The coupling mode of each component part of the pressure coupling hydraulic hybrid power driving circuit comprising the three-way pressure matcher is shown in fig. 2. In the loop, two external oil ports of an executing element are A1 and B1; a1 is an oil return port when the executive component bears a negative load and is also an oil inlet for the executive component to drive a positive load; b1 is an oil inlet when the executive component bears a negative load.
Modes of coupling the circuit components include, but are not limited to, the following: (1) The pressure oil port P of the multi-way reversing valve is connected with an outlet of the variable hydraulic pump, the oil return port T of the multi-way reversing valve is connected with an oil tank, the working oil port B of the multi-way reversing valve is connected with an actuating element oil port B1 (a second external oil port), and the working oil port A is connected with a three-way pressure matcher oil port K2; (2) The three-way pressure matcher oil port K3 is connected with the inflatable energy accumulator oil inlet and outlet port X, and the three-way pressure matcher oil port K1 is connected with the execution element oil port A1 (a first external oil port); (3) The pressure oil output by the variable hydraulic pump enters the port B1 of the executing element through the port B of the multi-way reversing valve under the control of the multi-way reversing valve, enters the oil port K2 of the three-way pressure matcher through the port A of the multi-way reversing valve, or is unloaded through the port T of the multi-way reversing valve; (4) The three oil ports of the three-way pressure matcher are provided with pressure sensors PU1, PU2 and PU3, and the sensors (including but not limited to the three sensors) transmit on-line detection values to a controller for controlling the displacement of the variable hydraulic pump and the opening of the multi-way reversing valve according to a pressure coupling algorithm.
In the coupling mode shown in fig. 2, the three-way pressure matcher has the following operation modes: when hydraulic oil flows from the port K1 to the ports K2 and K3, the motor of the port K2 (the left motor in the figure 2) is in a motor working condition, and the motor of the port K3 (the right motor in the figure 2) is in a pump working condition; when hydraulic oil flows from the ports K2 and K3 to the port K1, the motor of the port K2 (the left motor in fig. 2) is in the pump condition, and the motor of the port K3 (the right motor in fig. 2) is in the motor condition.
In 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 hydraulic oil flows from the port K1 to the ports K2 and K3, the motor of the port K2 (the left motor in the figure 2) is in a motor working condition, and the motor of the port K3 (the right motor in the figure 2) is in a pump working condition; when hydraulic oil flows from the ports K2 and K3 to the port K1, the motor of the port K2 (the left motor in fig. 2) is in the pump condition, and the motor of the port K3 (the right motor in fig. 2) is in the motor condition.
Although the addition of hydraulic components and piping to the circuit shown in fig. 2 is possible due to certain requirements, it is within the scope of the present invention as long as the above-described basic features are provided.
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. Therefore, neglecting 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 passing flow of the three oil ports K1, K2 and K3 of the three-way pressure matcher are respectively as follows: p1, q1, P2, q2, P3, q3. As shown in fig. 3. Then there are: p1.q2-p2.q2=p3.q3-p1.q3; namely: p1 (q2+q3) =p2·q2+p3·q3.
The flow continuity principle can be known: q1=q2+q3 (1)
The hydraulic power relationship is: p1.q1=p2.q2+p3.q3 (2)
When friction and internal leakage losses are considered, there is a loss of hydraulic power, which is expressed as the pressure loss Δp at the motor inlet. The value of Δp varies depending on the type and the type of the motor and the viscosity of the hydraulic oil, and is usually about 0.5Mpa, which can be measured by a test. The hydraulic power relationship at this time is:
（P1±△P）q1= P2·q2+ P3·q3 （3）
the connection modes of the circuit are considered as follows: p1=pa 1, p3=px, where PA1 is the load pressure of the positive load driving cavity (negative load oil return cavity) of the actuator, and PX is the oil inlet and outlet pressure of the pneumatic accumulator.
The method can obtain: (PA 1±Δp) q1=p2·q2+px·q3 (4)
When hydraulic oil flows to K1 from the K2 and K3 ports, the +number is taken; when hydraulic oil flows from the K1 port to the K2 and the K3 ports, the numbers are taken.
And (4) simultaneously to obtain the mathematical model of the pressure coupling algorithm in the loop.
According to the mathematical model of the pressure coupling algorithm, the pressure coupling hydraulic hybrid power driving circuit can ensure the stability of the pressure oil collecting and releasing function of the energy accumulator through the adjustment of the P2 value and the q2 value when the load pressure PA1 of the executing element changes or the oil pressure PX of the energy accumulator fluctuates in the field working condition, and is used for energy-saving operation (namely, ensuring the stability of the pressure oil collecting and releasing function of the energy accumulator) when the executing element is loaded with the positive and negative interval conversion working condition. Namely: when the negative load applies work to the executive component, the pressure coupling hydraulic hybrid power driving circuit can store the pressure oil generated in the oil return cavity of the executive component into the energy accumulator; the storage process can be smoothly performed even when the pressure of the oil return cavity of the actuating element is lower than the charging pressure of the accumulator, and is not influenced by load change. When the actuating element drives the external load, the pressure coupling hydraulic hybrid power driving circuit can input the pressure oil stored in the energy accumulator into the actuating element driving cavity to be used as auxiliary power, so that energy saving is realized, and the process is not influenced 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 hydraulic pump and the opening degree of the multi-way reversing valve. The displacement of the variable hydraulic pump and the opening of the multi-way reversing valve are reasonably regulated through a pressure coupling algorithm, so that the matching of the pressure values of three oil ports of the three-way pressure matcher and the load pressure PA1 of the executive component is realized, the function of the pneumatic energy 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 executive component, and the pneumatic energy accumulator can be effectively used for energy-saving operation when the load of the executive component has a positive-negative interval conversion working condition.
Examples
A practical application of the pressure coupled hydraulic hybrid power drive circuit of the present invention for driving the movable arm hydraulic cylinder of a hydraulic excavator is shown in fig. 4. The pressure coupling hydraulic hybrid power driving circuit of the hydraulic excavator movable arm hydraulic cylinder comprises a movable arm cylinder bearing gravity load, a three-way pressure matcher, an inflatable accumulator, a multi-way valve movable arm link, a variable hydraulic pump, a plurality of pressure sensors (P1, P2, P3, PA1 and PB 1) and a controller. The K1 oil port of the three-way pressure matcher is connected with the rodless cavity oil port A1 of the movable arm cylinder, the K2 oil port is connected with the working oil port A of the multi-way valve movable arm link, the K3 oil port is connected with the oil inlet and outlet port X of the inflatable accumulator, the rod cavity oil port B1 of the movable arm cylinder is connected with the working oil port B of the multi-way valve movable arm link, and the variable hydraulic pump is connected with the oil port P of the multi-way valve. The pilot controls of the multiplex valve boom linkage are pa7 and pb7, respectively.
In the actual working condition of the hydraulic excavator, the boom cylinder is required to bear the weight of the whole boom and the bucket (containing goods) of the hydraulic excavator, and the weight is converted into the force G of the piston rod end of the boom cylinder. When the movable arm of the hydraulic excavator descends, the piston rod of the movable arm cylinder is retracted, and G is a negative load; when the movable arm of the hydraulic excavator rises and the piston rod of the movable arm cylinder extends out, G is a positive load. If A1 is the boom cylinder rodless chamber pressure-bearing area and B1 is the boom cylinder rodless chamber pressure-bearing area, the boom cylinder rodless chamber oil pressure PA1 = (g+pb1·b1)/A1 is present no matter whether the boom is raised or lowered. In the formula, PB1 is the oil pressure of a rod cavity of the movable arm cylinder. In FIG. 4, the hydraulic pressure PX of the pneumatic accumulator should be about 5-10 MPa greater than PA1.
When pilot control oil pb7 of the multi-way valve movable arm link acts, the multi-way valve movable arm link is left, and pressure oil output by the variable hydraulic pump passes through a movable arm link B port to a movable arm cylinder rod cavity oil port B1. The negative load G drives the piston rod of the movable arm cylinder to retract, and oil returns from the rodless cavity of the movable arm cylinder to the port K1 of the three-way pressure matcher through the oil port A1. The oil return pressure is PA1, and the oil return flow rate is q 1. q1 enters the three-way pressure matcher and then is split into two paths, and the flow q2 passes through a left motor to be output from a K2 port and reaches an oil return box after a movable arm of the multi-way valve is connected with an A port. The flow q3 passes through the K3 port of the right motor and enters the energy accumulator for storage. Under the working condition, the inlet pressure P1 of the left motor is PA1, the outlet pressure P2 is approximately 0, the working condition of the motor is that the input hydraulic power is PA1 q2, and the output mechanical power is used for driving the right motor. At this time, the right motor is in a pump working condition, and mechanical power provided by the left motor is input to raise the inlet pressure PA1 to p3=px; the hydraulic power output from the right motor is (PX-PA 1). Q3. The hydraulic power of the internal leakage and friction loss of the three-way pressure matcher is expressed as pressure loss delta P, and the three-way pressure matcher has the following functions according to the law of conservation of energy:
PA1·q2-△P·q1=(PX-PA1)·q3
namely, PA1 (q2+q3) - [ delta ] P.q1=PX.q3 (5)
The flow continuity equation is based on: q1=q2+q3 (6)
(5) The formula is rewritable: PA1.q1- ΔP.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 at will after being determined, the q2 value is determined by the displacement of the variable pump, and the variable pump 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 the equation (7) true, even when PX is larger than PA1, the q2 value can be found. (6) And (7) the expression is a mathematical model of a pressure coupling algorithm of the descending working condition of the movable arm of the hydraulic excavator.
When pilot control oil PA7 of the multi-way valve movable arm link acts, the multi-way valve movable arm link is in a right position, pressure oil output by the variable hydraulic pump flows to a three-way pressure matcher K2 through a movable arm link A port, pressure oil stored by an accumulator flows into a right motor through the three-way pressure matcher K2 port, and the outlet pressure of the right motor is PA1. At this time, the right motor is in a motor working condition, the input hydraulic power is (PX-PA 1). Q3, the output mechanical power drives the left motor, the oil inlet pressure of the K2 port is increased from P2 to PA1, and the left motor is in a pump working condition. From the law of conservation of energy and the equation of continuity of flow, it is equally reasonable:
(PA1- P2)·q2+△P·q1=(PX-PA1)·q3
PA1·q1-P2·q2+△P·q1= PX（q1- q2） （8）
(6) And (8) the expression 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 the formulas (6) and (8), so that the determined PA1 and PX can be matched.
Typically, the drive circuit for the mobile arm cylinder of a hydraulic excavator is now in use as shown in fig. 5. The pressure coupling hydraulic hybrid power driving circuit is used for driving the movable arm hydraulic cylinder of the hydraulic excavator, so that the energy consumption of the hydraulic pump can be obviously reduced compared with the existing circuit shown in fig. 5, and energy conservation is realized. Let the travel of the lifting and descending of the movable arm hydraulic cylinder be L and the time be t.
In the working condition of the movable arm descending, the pressure PB1 of the movable arm hydraulic cylinder with a rod cavity is very small, the pressure PA1 of the movable arm hydraulic cylinder without the rod cavity is used for balancing gravity G, and the pressure PA1 is equal to the pressure bearing area of the rodless cavity. At this time, 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 the movable arm hydraulic cylinder of PA1 returns to an oil tank through a multi-way valve, and the pressure energy is changed into heat energy to be wasted. In the loop, after return oil with the pressure of a rodless cavity of a movable arm hydraulic cylinder of PA1 passes through a three-way pressure matcher, pressure oil with the flow rate of q2 drives a left motor to do work on a right motor, so that the oil pressure with the flow rate of q3 is increased from PA1 to PX and stored in an energy accumulator. Therefore, in the boom-down operation, in the pressure-coupled hydraulic hybrid drive circuit, the return oil having the boom cylinder rodless chamber pressure PA1 does not waste heat energy as in the conventional circuit, but is recovered and stored, and the theoretical value of the recovered pressure energy is wx= (PX-PA 1) ·q3·t.
In the working condition of lifting the movable arm, the pressure of the rodless cavity of the movable arm hydraulic cylinder is PA1, and the flow qA entering the rodless cavity of the existing loop shown in fig. 5 is the same as the flow q1 of the loop of the invention. That is, the hydraulic energy Wi that enters the boom cylinder rodless chamber in both circuits is substantially equal, wi= (G/a1) ·q1·t=pa 1·q1·t. However, in the existing circuit shown in FIG. 5, wi is provided entirely by the hydraulic pump; in the circuit of the present invention, wi is provided by both the hydraulic pump and the accumulator as auxiliary power. If the energy loss of the three-way pressure matcher is ignored, the accumulator can provide all the hydraulic energy Wx= (PX-PA 1) q3.t recovered and stored during the descending of the movable arm to the rodless cavity of the movable arm hydraulic cylinder, and the hydraulic pump only needs to provide the hydraulic energy (Wi-Wx). Therefore, in the pressure-coupled hydraulic hybrid drive circuit of the present invention, it is theoretically possible to save the energy consumption wx= (PX-PA 1) ·q3·t of the hydraulic pump in one cycle of the boom lowering and raising. For a 35 ton hydraulic excavator, the Wx is about 180-220 kilojoules, and the energy-saving effect is quite obvious.
Although the hydraulic components and pipelines can be added to the loop shown in fig. 4 according to certain requirements, other types of excavator hydraulic system combinations can be adopted, and the hydraulic system can be used for driving other execution elements of an excavator, the hydraulic hybrid power driving loop only has the basic characteristics (a three-way pressure matcher formed by coupling two energy conversion devices, a coupling mode of three oil ports of the pressure matcher in the loop, a mathematical model and a control method of a pressure coupling algorithm) of the hydraulic hybrid power driving loop, belongs to the implementation and application of the hydraulic hybrid power driving loop, and is the protection scope of the hydraulic hybrid power driving loop.
Claims (11)
1. The pressure coupling hydraulic hybrid power driving circuit is characterized by comprising a three-way pressure matcher, wherein a first oil port of the three-way pressure matcher is connected with a first oil port of an executing element; the second oil port of the three-way pressure matcher and the second outer oil port of the actuating element are connected with the hydraulic pump and the oil tank through the control valve; the third oil port of the three-way pressure matcher is connected with the oil port of the energy accumulator; the three-way pressure matcher comprises a first energy conversion device and a second energy conversion device; the oil ports at one side 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 three oil ports of the three-way pressure matcher meet 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 > = P < 2 >. Q < 2+ > 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) x (q2+q3) =P2.q2+PX.q3;
q2 and q3 are respectively the second oil port flow and the third oil port flow of the three-way pressure matcher; ΔP is the pressure loss at the inlet of the energy conversion device in the three-way pressure matcher; PA1 is the load pressure of the positive load driving cavity or the negative load oil return cavity of the executing element, PA1 = P1, and P1 is the pressure of the first oil port of the three-way pressure matcher; PX is the accumulator port pressure, px=p3, and P3 is the third port pressure of the three-way pressure matcher; and P2 is the pressure of a second oil port of the three-way pressure matcher.
2. The pressure coupled hydraulic hybrid drive circuit of claim 1, wherein the first energy conversion device and the second energy conversion device are hydraulic motors, and both hydraulic motors turn the same direction.
3. The pressure coupled hydraulic hybrid drive circuit of claim 2, wherein the hydraulic motor is in a motor condition or a pump condition.
4. The pressure coupled hydraulic hybrid drive circuit of claim 2, wherein the hydraulic motor is one of a plunger motor, a gear motor, and a vane motor.
5. The pressure coupled hydraulic hybrid drive circuit of claim 4, wherein the plunger motor comprises a radial plunger motor and an axial plunger motor; the gear motor comprises an inner meshing gear motor and an outer meshing gear motor; the vane motor includes a single-acting vane motor and a double-acting vane motor.
6. The pressure coupling hydraulic hybrid power driving circuit according to one of claims 1 to 5, wherein when the load pressure of the actuator changes and/or the accumulator oil inlet and outlet pressure fluctuates, the pressure and flow of the second oil port of the three-way pressure matcher are adjusted, so as 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 actuator.
7. The pressure-coupled hydraulic hybrid power driving circuit according to claim 6, 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 the control valve.
8. The pressure coupled hydraulic hybrid drive circuit of claim 1, wherein the control valve comprises a multiple directional 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 a second working oil port of the multi-way reversing valve is connected with a second external oil port of the executing element.
9. An excavator, characterized in that the excavator employs the pressure-coupled hydraulic hybrid power drive circuit according to any one of claims 1 to 8.
10. A control method of the pressure-coupled hydraulic hybrid drive circuit according to any one of claims 1 to 8, characterized by comprising: the matching of the pressure values of the three oil ports of the three-way pressure matcher and the load pressure of the executive component is realized by adjusting the pressure and the flow of the second oil port of the three-way pressure matcher; the three-way pressure matcher comprises a first energy conversion device and a second energy conversion device; the oil ports at one side 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;
and adjusting the pressure and flow of a second oil port of the three-way pressure matcher 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 > = P < 2 >. Q < 2+ > 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) x (q2+q3) =P2.q2+PX.q3;
q2 and q3 are respectively the second oil port flow and the third oil port flow of the three-way pressure matcher; ΔP is the pressure loss at the inlet of the energy conversion device in the three-way pressure matcher; PA1 is the load pressure of the positive load driving cavity or the negative load oil return cavity of the executing element, PA1 = P1, and P1 is the pressure of the first oil port of the three-way pressure matcher; PX is the accumulator port pressure, px=p3, and P3 is the third port pressure of the three-way pressure matcher; and P2 is the pressure of a second oil port of the three-way pressure matcher.
11. The method of claim 10, wherein the pressure and flow rate of the second port of the three-way pressure matcher are adjusted by controlling a displacement of the hydraulic pump and an opening degree of the control valve.
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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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| CN202010321320.2A CN113529843B (en) | 2020-04-22 | 2020-04-22 | Pressure coupling hydraulic hybrid power driving circuit, control method thereof and excavator |
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| JP2900839B2 (en) * | 1995-06-08 | 1999-06-02 | 株式会社新潟鉄工所 | Hydraulic circuits for injection molding machines, etc. |
| US7409826B2 (en) * | 2005-08-30 | 2008-08-12 | Grigoriy Epshteyn | Compact hydrostatic energy recuperation system and method of operation |
| DE102010010606B4 (en) * | 2010-03-08 | 2015-02-19 | Knorr-Bremse Systeme für Nutzfahrzeuge GmbH | Modular pressure control device of a pressure medium brake system of a vehicle |
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| CN105604121B (en) * | 2015-12-29 | 2017-09-29 | 太原理工大学 | A kind of control loop of engineer operation armament-related work device |
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| CN106223380B (en) * | 2016-08-31 | 2018-05-11 | 徐州徐工挖掘机械有限公司 | A kind of hydraulic hybrid excavator system |
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