CN114545908B - Method for constructing and simulating vehicle hydraulic system model and vehicle simulation system - Google Patents
Method for constructing and simulating vehicle hydraulic system model and vehicle simulation system Download PDFInfo
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Abstract
The embodiment of the invention discloses a method for constructing and simulating a hydraulic system model for a vehicle and a finished vehicle simulation system. The model construction method comprises the following steps: constructing a hydraulic motor model, a high-pressure hydraulic energy storage model, a low-pressure hydraulic energy storage model and a hydraulic accessory model in a simulation environment; correlating the hydraulic motor model, the high-pressure hydraulic energy storage model, the low-pressure hydraulic energy storage model and the hydraulic accessory model according to a signal relation to form a hydraulic system model; the construction process of the hydraulic motor model comprises the following steps: constructing a calculation formula for calculating the output flow of the hydraulic motor model according to the control signal input into the hydraulic motor model and the motor rotating speed; constructing a calculation formula of the torque loss of the hydraulic motor model according to the control signal; and constructing a calculation formula of the output torque of the hydraulic motor model according to the output flow and the torque loss. The embodiment improves the simulation precision.
Description
Technical Field
The embodiment of the invention relates to the technical field of simulation of a vehicle hydraulic system, in particular to a method for constructing and simulating a vehicle hydraulic system model and a vehicle simulation system.
Background
The modeling of the hydraulic system is an important means in the design and simulation analysis of the hydraulic system, and the establishment of the hydraulic system model is used for accurately representing various attributes of the hydraulic system and plays an indispensable role in the application and development process of the hydraulic system.
The existing modeling method of the vehicle hydraulic system is mostly based on foreign commercialized software. The module libraries provided in the hydraulic system modeling software are all packaged, so that a user cannot understand the implementation process of simulation, problems in the debugging process cannot be effectively eliminated, and the simulation precision is difficult to guarantee.
Disclosure of Invention
The embodiment of the invention provides a method for constructing and simulating a hydraulic system model for a vehicle and a finished vehicle simulation system, which accurately reflect the action mechanism in the model and improve the simulation precision.
In a first aspect, an embodiment of the present invention provides a method, including:
constructing a hydraulic motor model, a high-pressure hydraulic energy storage model, a low-pressure hydraulic energy storage model and a hydraulic accessory model in a simulation environment;
correlating the hydraulic motor model, the high-pressure hydraulic energy storage model, the low-pressure hydraulic energy storage model and the hydraulic accessory model according to a signal relation to form a hydraulic system model;
the construction process of the hydraulic motor model comprises the following steps:
constructing a calculation formula for calculating the output flow of the hydraulic motor model according to the control signal input into the hydraulic motor model and the motor rotating speed;
constructing a calculation formula of the torque loss of the hydraulic motor model according to the control signal;
constructing a calculation formula of the output torque of the hydraulic motor model according to the output flow and the torque loss;
wherein the control signal is representative of an operating state of the hydraulic motor.
In a second aspect, the embodiment of the invention provides a simulation method for a vehicle hydraulic system, which is applied to a vehicle hydraulic system model, wherein the hydraulic system model is constructed by adopting the method;
the simulation method comprises the following steps:
and determining the optimal solution of the output torque according to each calculation equation constructed in the hydraulic system model, and taking the optimal solution as the output of the hydraulic system model.
In a third aspect, an embodiment of the present invention further provides a finished automobile simulation system, including: the hydraulic system model, the engine model, the clutch model, the transmission model and the torque coupler model;
in the whole vehicle simulation process, the output torque of the engine model passes through the clutch model and the transmission model and then is input into the torque coupler model; the torque coupler model is used for coupling and outputting the torque from the hydraulic system model and the engine model.
According to the embodiment of the invention, the hydraulic motor, the high-pressure hydraulic energy accumulator, the low-pressure hydraulic energy accumulator and the hydraulic accessory are selected as necessary components of the hydraulic system to be respectively modeled, and a relation model for constraining input parameters and/or output parameters in the hydraulic motor model is constructed through detailed analysis of the mechanism of the hydraulic motor model, so that the dynamic change process of the internal pressure of the system is accurately reflected. Meanwhile, a control equation for associating each component model is constructed through the real pipeline connection relation of each component, so that each component model forms a unified whole. And the relation model in the component model and a control equation between the component models jointly form a relation model of the input parameters and the output parameters of the hydraulic system model, so that the modeling of the hydraulic system is completed. The hydraulic system model can accurately calculate the motor torque output by the hydraulic system due to the change of the internal pressure, and improves the simulation precision. In particular, the embodiment considers the torque loss when the hydraulic motor operates and does not operate, so that the hydraulic system model is closer to the actual operation process of the hydraulic system, and the accuracy of the hydraulic system simulation model is improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
Fig. 1 is a flowchart of a method for building a hydraulic system model for a vehicle according to an embodiment of the present invention.
Fig. 2 is a structural diagram of a hydraulic system model for a vehicle according to an embodiment of the present invention.
Fig. 3 is a schematic diagram of signal relationships between models of the hydraulic components shown in fig. 2.
Fig. 4 is a flowchart of a simulation method for a hydraulic system of a vehicle according to an embodiment of the present invention.
Fig. 5 is a schematic structural diagram of a finished automobile simulation system according to an embodiment of the present invention.
FIG. 6 is a schematic vehicle speed diagram for operation under NEDC (New European Driving Cycle) conditions.
FIG. 7 is a diagram of the change in SOC (state of energy storage) of the hydraulic accumulator model when the entire vehicle simulation system shown in FIG. 5 is operating under the NEDC condition of FIG. 6.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplification of description, but do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the present invention, it should also be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
Fig. 1 is a flowchart of a method for building a hydraulic system model for a vehicle according to an embodiment of the present invention, and is suitable for a situation where a simulation model of a hydraulic system for a vehicle is built in a simulation environment. The method is executed by an electronic device, and as shown in fig. 1, the method comprises the following steps:
s110, constructing a hydraulic motor model, a high-pressure hydraulic energy storage model, a low-pressure hydraulic energy storage model and a hydraulic accessory model in a simulation environment;
a real vehicular hydraulic system includes a plurality of hydraulic components: the hydraulic system comprises a high-pressure hydraulic accumulator, a low-pressure hydraulic accumulator, a hydraulic motor, a hydraulic pump, an electric motor, a hydraulic valve, an oil tank, an oil filter, a cooler, a heater, a pressure gauge, a hydraulic filter, a return oil filter, a pressure gauge and the like, wherein all hydraulic components are connected through hydraulic pipelines. When the high-pressure hydraulic accumulator and the low-pressure hydraulic accumulator are connected into the hydraulic circuit, a pressure difference is generated in the hydraulic circuit; at the moment, if the hydraulic motor has an operation signal, oil flows out of the high-pressure hydraulic energy accumulator and passes through the hydraulic motor to drive the hydraulic motor to rotate and flow to the low-pressure hydraulic energy accumulator, and the pressure difference between the two ends of the hydraulic motor enables the hydraulic motor to continuously operate.
It can be seen that the high pressure hydraulic accumulator, the low pressure hydraulic accumulator and the hydraulic motor are the most important components of the hydraulic system, and the main components of the remaining components may be collectively referred to as hydraulic accessories, such as a hydraulic filter, a return oil filter and a pressure gauge. This embodiment does not model each component in the hydraulic system, but builds a model of the hydraulic system for a vehicle as shown in fig. 2, immediately surrounding the most important components and the main components of the rest of the components, and includes: the hydraulic system comprises a hydraulic motor model, a high-pressure hydraulic energy storage model, a low-pressure hydraulic energy storage model and a hydraulic accessory model.
And S120, associating the hydraulic motor model, the high-pressure hydraulic energy storage model, the low-pressure hydraulic energy storage model and the hydraulic accessory model according to a signal relation to form a hydraulic system model.
Fig. 3 is a schematic diagram of signal relationships between models of the hydraulic components shown in fig. 2. Referring to fig. 2 and 3, since the pressure and flow of the ports of the components connected by the pipelines in the real hydraulic system are consistent, the output flow and output pressure of the high-pressure hydraulic accumulator model in the hydraulic system simulation model are equal to the input flow and input pressure of the hydraulic accessory model, the output flow and output pressure of the hydraulic accessory model are equal to the input flow and input pressure of the hydraulic motor model, and the output flow and output pressure of the hydraulic motor model are equal to the input flow and input pressure of the low-pressure hydraulic accumulator model. In the embodiment, control equations among the models of the components are established through the signal relations, and the models of the components are associated, so that a complete system model is obtained.
Specifically, the control equation for associating the component models is as follows:
Q ess_oil_flow_outlet =Q acc_flow_in （1）
P ess = P acc_in （2）
Q acc_flow_out = Q mothy_in （3）
P acc_out = P mothy_in （4）
Q mothy_flow = Q ess_oil_flow_outlet （5）
P mothy_out =P ess_low （6）
wherein the content of the first and second substances,Q ess_oil_flow_outlet andP ess respectively representing the output flow and the output pressure of the high-pressure hydraulic accumulator model,Q acc_flow_in andP acc_in respectively representing an input flow and an input pressure of the hydraulic attachment model,Q acc_flow_out andP acc_out respectively representing the output flow and the output pressure of the hydraulic attachment model,Q mothy_in andP mothy_in respectively representing the input flow and the input pressure of the hydraulic motor model,Q mothy_flow andP mothy_out respectively representing the output flow and the output pressure of the hydraulic motor model,Q ess_oil_flow_outlet andP ess_low respectively representing the input flow and the input pressure of the low-pressure hydraulic accumulator model.
It can be seen that according to the characteristics of the two hydraulic accumulator models, the output flow of the high-pressure hydraulic accumulator model is equal to the input flow of the low-pressure hydraulic accumulator model, and the output flow isQ ess_oil_flow_outlet 。
Further, the input parameters of the hydraulic system simulation model comprise control signals and motor rotating speed of the hydraulic motor model, and the output parameters comprise output torque of the hydraulic motor model. The motor rotation speed refers to the rotation speed of the hydraulic motor, and the output torque refers to the torque of the hydraulic motor. The construction process of the hydraulic system model is the construction process of a relation model of input parameters and output parameters of the hydraulic system model. The following describes the construction process of each component model with reference to fig. 2 and fig. 3, and finally obtains a relationship model of the input parameters and the output parameters of the hydraulic system model.
As shown in fig. 3, the oil flow direction of the "high-pressure hydraulic accumulator model- > hydraulic accessory model- > hydraulic motor model- > low-pressure hydraulic accumulator model" is formed in the whole hydraulic system simulation model. When the flow direction of each model port is positive, the hydraulic motor model is in a hydraulic motor state; when the flow direction of each model port is negative, the hydraulic motor model is in a hydraulic pump state, thereby forming a hydraulic circuit. Next, the starting point of the oil flow, i.e., the process of constructing the high-pressure hydraulic accumulator model, will be described first according to the flow direction shown in fig. 3.
The high-pressure hydraulic accumulator model has no special input parameters, and the output parameters comprise output pressure and output flow. Therefore, in the process of constructing the high-pressure hydraulic accumulator model, a relation model between the known parameters and the output parameters needs to be constructed, and the method specifically comprises the following steps:
step one, constructing a calculation formula of the volume of gas accumulated and expanded by a high-pressure hydraulic energy storage model through integration of output flow of the high-pressure hydraulic energy storage model:
wherein the content of the first and second substances,
indicating the gas volume of the accumulated expansion of the hydraulic oil in the high-pressure hydraulic accumulator,
representing the output flow of the high-pressure hydraulic accumulator model,trepresenting time.
And step two, determining a calculation formula of the gas temperature of the high-pressure hydraulic energy storage model according to the heat exchange between the gas and the wall surface and between the gas and the oil in the high-pressure hydraulic energy storage. Specifically, firstly, a calculation formula of the heat loss power of the high-pressure hydraulic energy storage model is constructed:
wherein, the first and the second end of the pipe are connected with each other,
represents the heat loss power of the high-pressure hydraulic accumulator model,
represents the heat transfer coefficient of the high-pressure hydraulic accumulator,
the effective area of the high-pressure hydraulic accumulator for heat dissipation is shown,
indicating the hydraulic oil temperature of the high-pressure hydraulic accumulator,
representing the gas temperature at a time on the high-pressure hydraulic accumulator model.
、
And
is the actual parameter of the high-pressure hydraulic accumulator and is considered to be a known quantity.
Then, according to the heat loss power, a calculation formula of the gas temperature of the high-pressure hydraulic energy storage model is constructed:
wherein, the first and the second end of the pipe are connected with each other,
representing the current gas temperature of the high-pressure hydraulic accumulator model,
represents the adiabatic coefficient of the high-pressure hydraulic accumulator;
the gas temperature at the moment on the high-pressure hydraulic energy storage model is represented and stored by the delay module;
representing the output flow of the high-pressure hydraulic accumulator model,
indicating the gas volume of the accumulated expansion of the hydraulic oil in the high-pressure hydraulic accumulator,
represents the heat loss power of the high-pressure hydraulic accumulator model,
representing the heat capacity of the high pressure hydraulic accumulator. It can be seen that the calculation formula for the gas temperature of the hydraulic accumulator is divided into two parts, the former representing the heat exchange between the accumulator wall and the gas and the latter representing the heat exchange between the gas and the oil.
Thirdly, according to the gas volume and the gas temperature, a calculation formula of the output pressure of the high-pressure hydraulic energy storage model is established:
wherein the content of the first and second substances,
represents the output pressure of the high-pressure hydraulic accumulator model,
representing the initial pressure of the high-pressure hydraulic accumulator,
representing the initial volume of the high-pressure hydraulic accumulator,
indicating the initial temperature of the gas of the high-pressure hydraulic accumulator,
indicating the gas volume of the accumulated expansion of the hydraulic oil in the high-pressure hydraulic accumulator,
representing the current gas temperature of the high-pressure hydraulic accumulator model.
Is a preset value.
With continued reference to fig. 3, the output flow and the output pressure of the high-pressure hydraulic accumulator model are input to the hydraulic attachment model as the input flow and the input pressure of the hydraulic attachment model, respectively. In the process of constructing the hydraulic accessory model, a relation model between input parameters and output parameters needs to be constructed. Optionally, the construction process comprises the following steps:
step one, according to the input pressure of the hydraulic accessory model, a calculation formula of the output pressure of the hydraulic accessory model is constructed. Because the hydraulic attachment does not affect the pressure, the output pressure of the hydraulic attachment model is equal to the input pressure:
P acc_out =P acc_in （11）
wherein the content of the first and second substances,P acc_in representing the input pressure of the hydraulic attachment model,P acc_out representing the output pressure of the hydraulic attachment.
Step two, according to the speed of the whole vehicle, a calculation formula of the output flow of the hydraulic accessory model is established:
wherein the content of the first and second substances,
representing the output flow of the hydraulic attachment model,
is the input flow of the hydraulic attachment model,
for the flow loss of the hydraulic attachment model,
indicating the vehicle speed. The hydraulic accessories include hydraulic valves, hydraulic filters, oil return filters, pressure gauges and the like, and when oil passes through the valve bodies, the cross-sectional flow area changes, and flow loss is generated. When the vehicle speed exists, (the absolute value of the vehicle speed is larger than a set threshold value, such as 0.01), the oil flows, and the flow loss exists. When the vehicle speed does not exist (the absolute value of the vehicle speed is less than or equal to a set threshold value, such as 0.01), the oil does not flow, and no flow loss exists.
Related to the actual properties of the hydraulic attachment, are considered known.
With continued reference to fig. 3, the output pressure and the output flow of the hydraulic attachment model are input to the hydraulic motor model as the input flow and the input pressure of the hydraulic motor model, respectively, to form two input parameters of the hydraulic motor model. In addition, the hydraulic motor model also includes two input parameters: control signals and motor speed. The output parameters of the hydraulic motor model include output flow, output pressure, and motor torque. Wherein the control signal is representative of the operating state of the hydraulic motor. The value range of the control signal is between [ -1, 1 ]; when the control signal is positive, the hydraulic motor rotates forwards, and oil flows from the high-pressure hydraulic energy accumulator to the low-pressure hydraulic energy accumulator; when the control signal of the hydraulic motor is negative, the hydraulic motor rotates reversely, oil is pressed to the high-pressure hydraulic energy accumulator from the low-pressure hydraulic energy accumulator, and the energy accumulator is charged. Further, if the absolute value of the control signal is smaller than a set threshold (e.g., 0.0001, considered close to 0), the hydraulic motor is operated; if the absolute value of the control signal is greater than or equal to a set threshold (e.g., 0.0001, which is considered not close to 0), the hydraulic motor is not operated.
The hydraulic motor model is the most important part of the whole hydraulic system model. In the process of constructing the hydraulic motor model, a relation model between the input parameters and the output parameters needs to be constructed. Optionally, the construction process comprises the steps of:
and S1, constructing a calculation formula for calculating the output flow of the hydraulic motor model according to the control signal input into the hydraulic motor model and the motor rotating speed.
Optionally, the hydraulic motor model comprises a hydraulic rotor model, a hydraulic actuator model and a flow calculation model; the method for constructing the calculation formula for calculating the output flow of the hydraulic motor model according to the control signal input into the hydraulic motor model and the motor rotating speed comprises the following steps of:
step one, according to the control signal and the motor rotating speed input into the hydraulic motor model, a calculation formula of the output flow of the hydraulic rotor model is established.
Specifically, first, a theoretical flow rate of the hydraulic motor is constructed from the control signal and the motor speed input to the hydraulic motor model:
wherein the content of the first and second substances,
which represents the theoretical flow of the hydraulic motor,
a control signal representing a model of the hydraulic motor,
which represents the maximum displacement of the hydraulic motor,
indicating the motor speed.
Is the actual parameter of the hydraulic motor and is considered known.
Then, according to the theoretical flow, a calculation formula of the output flow of the hydraulic rotor model is constructed:
wherein the content of the first and second substances,
represents the output flow of the hydraulic rotor model,
indicating the volumetric efficiency of the hydraulic motor.
The method is obtained by looking up a table through three parameters of a control signal of the hydraulic motor model, the rotating speed of the hydraulic motor and the input pressure of the hydraulic motor model.
And secondly, constructing a calculation formula of the output flow of the hydraulic actuator model according to the control signal and the working time of the hydraulic actuator model.
The control signal is also input into the hydraulic actuator model at the same time, and a calculation formula of the flow increasing of the hydraulic actuator model is firstly constructed according to the control signal and the working time:
wherein, the first and the second end of the pipe are connected with each other,
representing the incremental flow of the hydraulic actuator model,
the working time of the hydraulic actuator model is represented,
to represent
Control signal in time
The amount of change in the absolute value of (c),
representing the maximum flow of the hydraulic actuator model.
Are the actual parameters of the hydraulic actuator and are considered known.
Then, according to the increased flow and the leakage flow, a calculation formula of the output flow of the hydraulic actuator model is constructed:
wherein the content of the first and second substances,
represents the output flow of the hydraulic actuator model,
representing the leakage flow of the hydraulic actuator model.
The leakage flow of the actuator model can be obtained through a known lookup table model, and the leakage flow of the actuator model is obtained through lookup tables of differential pressure at two ends of the hydraulic motor.
It should be noted that, the first step and the second step may be performed simultaneously, and there is no restriction on the order.
Thirdly, according to the output flow of the hydraulic rotor model and the output flow of the hydraulic actuator, a calculation formula of the output flow of the hydraulic motor model is established:
wherein the content of the first and second substances,
the output flow of the hydraulic motor model is represented,
represents the output flow of the hydraulic rotor model,
representing the output flow of the hydraulic actuator model.
In summary, S1 builds a model of the relationship between the input parameters and the output flow of the hydraulic motor model, and S2 and S3 will build a model of the relationship between the input parameters and the output torque.
And S2, constructing a calculation formula of the torque loss of the hydraulic motor model according to the control signal.
The torque loss refers to the torque loss of the hydraulic motor caused by various friction and resistance in the operation process, and is an important factor influencing the output torque of the hydraulic motor model. The embodiment takes into account the torque losses in different operating states of the hydraulic motor. Specifically, when the control signal is not close to 0, and the hydraulic motor is in an operating state, the torque loss is mainly caused by mechanical friction between relative movements in the hydraulic motor. When the control signal is close to 0, the hydraulic motor is not operated, and the torque loss is mainly caused by the oil viscous resistance of the oil in the motor.
For the sake of convenience of distinction and description, the torque loss due to mechanical friction is referred to as a first torque loss, and the torque loss due to oil viscous resistance is referred to as a second torque loss. Optionally, the constructing a calculation formula of the torque loss of the hydraulic motor model according to the control signal includes: when the absolute value of the control signal is larger than a set threshold value, constructing a calculation formula of the torque loss of the hydraulic motor model according to a first torque loss caused by mechanical friction when the hydraulic motor operates; and when the absolute value of the control signal is smaller than or equal to the set threshold, constructing a calculation formula of the torque loss of the hydraulic motor model according to a second torque loss caused by the oil viscous resistance when the hydraulic motor does not operate.
Wherein, the first and the second end of the pipe are connected with each other,T loss representing the torque loss of the hydraulic motor model,T mothy_loss representing a first torque loss caused by mechanical friction when the hydraulic motor is running,T dmd_drag representing a second torque loss caused by the viscous resistance of the oil when the hydraulic motor is not operating,
indicating that a threshold is set.
Optionally, the first torque loss and the second torque loss are obtained by using a pressure-torque loss interpolation table of a hydraulic motor; the set threshold is set according to actual needs, for example, 0.0001.
And S3, constructing a calculation formula of the output torque of the hydraulic motor model according to the output flow and the torque loss.
And calculating the output torque of the hydraulic motor model, wherein the lossless torque and the torque loss of the hydraulic motor are required to be considered. The lossless torque refers to torque which is generated when the hydraulic motor operates and has no loss, is derived from mechanical rotation of the hydraulic motor driven by oil, and can be determined according to the input flow of a hydraulic motor model. According to the output flow and the torque loss, a calculation formula of the output torque of the hydraulic motor model is constructed, and the method specifically comprises the following steps:
step one, according to the output flow direction of the hydraulic motor model, a calculation formula of the pressure drop of the hydraulic motor model is established:
wherein, the first and the second end of the pipe are connected with each other,P mothy_drop a pressure drop of the hydraulic motor model is shown,P mothy_in is the input pressure of the hydraulic motor model,
a first positive pressure drop coefficient indicative of the hydraulic motor,
a second positive pressure drop coefficient indicative of the hydraulic motor,
a first negative pressure drop coefficient of the hydraulic motor is indicated,
indicating liquidA second negative pressure drop coefficient of the pressure motor,
indicating the ratio of the pressure drop of the hydraulic motor,Q mothy_flow representing an output flow of the hydraulic motor model. Wherein the content of the first and second substances,P mothy_in are input parameters of the hydraulic motor model,
、
、
、
and
determined by the properties of the hydraulic motor itself, is considered known.
It can be seen that formula (19) considers the output flow of the hydraulic motor in both forward and reverse directions. When the output flow is positive, the oil drives the hydraulic motor to rotate forwards, and the pressure difference between the inlet and the outlet of the hydraulic motor is reduced; when the output flow is negative, the hydraulic motor rotates reversely, and the pressure difference between the inlet and the outlet of the hydraulic motor is increased.
From the pressure drop, a model of the relationship between input pressure and output pressure can also be calculated:
P mothy_drop =P mothy_in -P mothy_out （20）
wherein, the first and the second end of the pipe are connected with each other,P mothy_drop representing the pressure drop of the hydraulic motor model,P mothy_in is the input pressure of the hydraulic motor model,P mothy_out representing the output pressure drop of the hydraulic motor model.
And step two, constructing a calculation formula of the lossless torque of the hydraulic motor model according to the pressure drop and the power flow direction of the hydraulic motor model.
The power flow direction refers to the direction of energy flow in the whole vehicle and is determined according to the control signal and the motor rotating speed. Specifically, the hydraulic motor model multiplies the control signal and the motor rotating speed to obtain the power of the hydraulic motor, and then judges the sign of the power through sign (), so that the power flow direction is obtained. The positive and negative of the control signal represent the running state of the hydraulic motor, and when the control signal is positive, the hydraulic motor is in a hydraulic motor state; when the control signal is negative, it represents that the hydraulic motor is in the hydraulic pump state. The positive and negative of the output rotating speed represent the running state of the whole vehicle, and when the output rotating speed is positive, the vehicle accelerates; when the output rotating speed is negative, the whole vehicle is decelerated and retreated. The power flow direction therefore represents the overall representation of the state of the hydraulic motor and the driving state of the entire vehicle.
The formula for calculating the loss-free torque is as follows:
wherein the content of the first and second substances,
representing a loss-free torque of the hydraulic motor model,
it is the mechanical efficiency of the hydraulic motor,
a control signal representing a model of the hydraulic motor,
which represents the maximum displacement of the hydraulic motor,P mothy_drop representing the pressure drop of the hydraulic motor model,
representing the power flow direction of the hydraulic motor model.
The control signal of the hydraulic motor model, the rotating speed of the hydraulic motor and the input pressure of the hydraulic motor model are obtained by looking up a table,
are the actual parameters of the hydraulic motor and are considered known.
It can be seen that the power flow of the hydraulic motor model is considered in equation (21) for the forward and reverse directions, respectively: when the power flow is positive, the hydraulic motor rotates forwards, oil flows from the high-pressure hydraulic energy accumulator to the low-pressure hydraulic energy accumulator, the hydraulic energy accumulator releases energy, and the lossless torque of the hydraulic motor model is equal to the theoretical torque multiplied by the mechanical efficiency; when the power flow is negative, the hydraulic motor rotates reversely, which is equivalent to the state of a hydraulic pump, oil is pressed from the low-pressure hydraulic energy accumulator to the high-pressure hydraulic energy accumulator, the hydraulic energy accumulator is charged, and the lossless torque of the hydraulic motor model is equal to the theoretical torque divided by the mechanical efficiency.
And step three, constructing a calculation formula of the output torque of the hydraulic motor model according to the lossless torque and the torque loss under different control signals.
Combining the formula (18) and the formula (21), a calculation formula of the output torque is obtained:
wherein the content of the first and second substances,
represents the output torque of the hydraulic motor model,
a control signal representing a model of the hydraulic motor,T mothy_loss indicating hydraulic motor motionA first loss of torque caused by mechanical friction while traveling,T dmd_drag representing a second torque loss due to oil viscous drag when the hydraulic motor is not operating.
It is generally considered that when the control signal is close to 0, the hydraulic motor is not operated, there is no loss-free torque and torque loss, and thus the output torque of the hydraulic motor model is zero. This does not take into account the torque loss when the hydraulic motor control signal is close to 0, which increases the torque loss in this case, i.e. when the hydraulic motor is not running.
In the embodiment, the hydraulic motor model respectively constructs calculation formulas of the output flow of the hydraulic rotor model and the output flow of the hydraulic actuator model according to the control signals, so that the calculation formula of the output flow of the hydraulic motor model is obtained; and then, considering the torque loss of the hydraulic motor in different running states, adding the lossless torque and the torque loss generated by the hydraulic motor to construct a calculation formula of the output torque of the hydraulic motor model. All the above equations constitute a model of the relationship between the hydraulic motor model input parameters and output parameters. In the whole construction process of the relation model, the influence of the output flow direction and the power flow direction of the hydraulic motor model on each parameter and the torque loss of the hydraulic motor in different running states are fully considered, different calculation relations are set for various parameter combinations, the simulation model has higher precision, and a more accurate simulation result is obtained.
With continued reference to fig. 3, the output torque of the hydraulic motor model is output as an output parameter of the entire hydraulic system model; and the output flow and the output pressure of the hydraulic motor model are respectively input into the low-pressure hydraulic energy storage model and used as the input flow and the input pressure of the low-pressure hydraulic energy storage model. The low-pressure hydraulic accumulator model has no additional output parameters, so that a relation model between known parameters and input parameters needs to be constructed in the construction process of the low-pressure hydraulic accumulator model. Optionally, the construction process comprises the following steps:
step one, integrating input flow of a low-pressure hydraulic energy storage model to construct a calculation formula of accumulated compressed gas volume of the low-pressure hydraulic energy storage model:
wherein, the first and the second end of the pipe are connected with each other,
representing the gas volume of the accumulated compression of the low-pressure hydraulic accumulator model;
an input flow representing a low pressure hydraulic accumulator model;trepresenting time.
And step two, determining a calculation formula of the gas temperature of the low-pressure hydraulic energy storage model according to the heat exchange between the gas and the wall surface and between the gas and the oil in the low-pressure hydraulic energy storage. Specifically, firstly, a calculation formula of the heat loss power of the low-pressure hydraulic accumulator model is constructed:
wherein the content of the first and second substances,
representing the heat loss power of the low-pressure hydraulic accumulator model;
the heat transfer coefficient of the low-pressure hydraulic energy accumulator is represented and is equal to that of the high-pressure hydraulic energy accumulator;
the effective area of the low-pressure hydraulic energy accumulator for heat dissipation is equal to the effective area of the high-pressure hydraulic energy accumulator for heat dissipation;
the hydraulic oil temperature of the low-pressure hydraulic energy accumulator is shown and is the same as that of the high-pressure hydraulic energy accumulator;
representing the gas temperature at the moment on the low pressure hydraulic accumulator model.
The actual parameters of the low-pressure hydraulic accumulator, which are identical to the three parameters of the high-pressure hydraulic accumulator, are known.
Then, according to the heat loss power, a calculation formula of the gas temperature for constructing a low-pressure hydraulic energy storage model is as follows:
wherein the content of the first and second substances,
representing the current gas temperature of the low-pressure hydraulic accumulator model;
represents the adiabatic coefficient of the low-pressure hydraulic accumulator, which is equal to the adiabatic coefficient of the high-pressure hydraulic accumulator;
representing the gas temperature at the last instant of the low-pressure hydraulic accumulator model,
representing the input flow of the low-pressure hydraulic accumulator model,
representing the cumulative compressed gas volume of the low pressure hydraulic accumulator model,
representing the heat loss power of the low-pressure hydraulic accumulator model;
the heat capacity of the low-pressure hydraulic accumulator is represented and is equal to that of the high-pressure hydraulic accumulator. It can be seen that the formula for calculating the gas temperature of the low-pressure hydraulic accumulator is divided into two parts, the former representing the heat exchange between the accumulator wall and the gas and the latter representing the heat exchange between the gas and the oil.
Thirdly, constructing a relation model which satisfies the input pressure of the low-pressure hydraulic energy storage model according to the gas volume and the gas temperature:
wherein the content of the first and second substances,P ess_low the representation represents the input pressure of the low-pressure hydraulic accumulator,
indicating the initial pressure of the low-pressure hydraulic accumulator,
representing the initial volume of the low pressure hydraulic accumulator,
indicating the initial temperature of the gas of the low-pressure hydraulic accumulator,
is the volume of gas compressed by oil in the low-pressure hydraulic energy accumulator,
is the gas temperature of the low pressure hydraulic accumulator.
、
And
is a preset value.
In summary, in the embodiment, a hydraulic motor, a high-pressure hydraulic accumulator, a low-pressure hydraulic accumulator and a hydraulic attachment are selected as necessary components of a hydraulic system to be modeled respectively, a relationship model (formulas (7) - (26)) for constraining input parameters and/or output parameters in each component model is constructed through detailed analysis of mechanism of each component model, and a dynamic change process of pressure inside the system is accurately reflected. Meanwhile, control equations (formulas (1) - (6)) for associating the models of the components are constructed through the real pipeline connection relation of the components, so that the models of the components form a unified whole. And (3) a control equation between the relation model inside the component model and the component model jointly forms a relation model (formulas (1) - (26)) of the input parameters and the output parameters of the hydraulic system model, so that the modeling of the hydraulic system is completed. The hydraulic system model can accurately calculate the motor torque output by the hydraulic system due to the change of the internal pressure, and improves the simulation precision. In particular, the embodiment considers the torque loss of the hydraulic motor when the control signal is close to 0 and not close to 0, and the influence of the input flow direction, the power flow direction and the like on the operation of the hydraulic system, so that the hydraulic system model is closer to the actual operation process of the hydraulic system, and the accuracy of the hydraulic system simulation model is improved.
Fig. 4 is a flowchart of a simulation method for a vehicle hydraulic system according to an embodiment of the present invention, and is applied to the vehicle hydraulic system model to implement simulation of the hydraulic system. As shown in fig. 4, the method includes:
s210, determining an optimal solution of the output torque according to each calculation equation constructed in the hydraulic system model, and taking the optimal solution as the output of the hydraulic system model.
The embodiment is realized based on the hydraulic system model constructed in the above embodiment. When the hydraulic system is simulated, the hydraulic system model determines the optimal solution of the output torque as the output of the hydraulic system model by using the control equation and the relation model (equations (1) - (26)) as constraint conditions and adopting simulation calculation methods such as ant colony algorithm, genetic algorithm and the like. Optionally, the simulation environment is Simulink simulation software, and the specific calculation process is implemented by a solver, which is not described herein again.
The present embodiment is implemented based on any one of the above embodiments, and has the technical effects of any one of the above embodiments.
Fig. 5 is a schematic structural diagram of a finished automobile simulation system according to an embodiment of the present invention. As shown in fig. 5, the entire vehicle simulation system includes: a vehicle hydraulic system model, an engine model, a clutch model, a transmission model, a torque coupling model (i.e., a portion within the range of the dotted line in fig. 5). The vehicle hydraulic system model is constructed by adopting the method of any one of the embodiments, and can execute the simulation method in the embodiments.
In the whole vehicle simulation process, the output torque of the engine model passes through the clutch model and the transmission model and then is input into the torque coupler model; the torque coupler model is used for coupling and outputting the torque from the hydraulic system model and the engine model.
Optionally, the entire vehicle simulation system further includes: an ECU (Electronic Control Unit) model. In the whole vehicle simulation process, the ECU model is used for respectively sending control signals to the vehicle hydraulic system model and the engine model according to the running condition of the whole vehicle, and the control signals respectively represent the running states of the hydraulic motor and the engine
Because the whole vehicle simulation system comprises two power sources, namely an engine model and a hydraulic accumulator model, the whole vehicle simulation system has the characteristics of good dynamic property of a fuel engine and pollution-free and low noise of a hydraulic system. The ECU model respectively sends respective control signals to the vehicle hydraulic system model and the engine model so as to simulate the cooperative working state of the two power sources, and the working point of the engine is adjusted to obtain the optimal fuel economy.
Specifically, when the whole vehicle is in a starting working condition, a hydraulic energy accumulator of a hydraulic system provides power for a hydraulic motor, so that the whole vehicle has good acceleration performance, and the characteristic that the hydraulic motor generates large torque at low speed is exerted; the whole vehicle has good dynamic property and good fuel economy. Under the working condition, the ECU model sends a control signal to the vehicle hydraulic system model, and does not send a control signal to the engine model, and the whole vehicle simulation system simulates the state of independent operation of the hydraulic motor.
When the whole vehicle is in an accelerating or climbing state, the hydraulic motor and the engine run simultaneously, and the hydraulic motor provides auxiliary power to accelerate and climb the whole vehicle. Under the working condition, the ECU model sends control signals to the hydraulic system model and the engine model for the vehicle, and the whole vehicle simulation system simulates the state of the engine and the hydraulic motor which operate simultaneously.
When the vehicle runs at a high speed, the engine works in a high-efficiency and low-emission area, and the engine independently provides power for the whole vehicle. Under the working condition, the ECU model sends a control signal to the engine model, and does not send a control signal to the vehicle hydraulic system, and the whole vehicle simulation system simulates the independent running state of the engine.
When the charge energy level of the hydraulic energy accumulator is lower, the engine drives the hydraulic motor to rotate reversely to charge the hydraulic energy accumulator. Under the working condition segment, the ECU model sends a negative control signal to the vehicle hydraulic system model, and the whole vehicle simulation system simulates the state of 'reversing the hydraulic motor and charging the hydraulic energy accumulator'.
When the vehicle is in a deceleration or braking state, the hydraulic motor rotates reversely to recover braking energy and charge the hydraulic energy accumulator, so that the pressure of the hydraulic energy accumulator is increased to realize regenerative braking. Under the working condition segment, the ECU model sends a negative control signal to the vehicle hydraulic system model, and the whole vehicle simulation system simulates the state of 'reversing the hydraulic motor, recovering the braking energy and charging the hydraulic energy accumulator'.
Optionally, the entire vehicle simulation system further includes: wheel and brake models, and final drive models. The ECU model controls the wheel and brake model to carry out speed reduction and brake simulation, the main reducer model transmits torque to the wheel and brake model and is used for calculating the speed of the whole vehicle and inputting the speed into the hydraulic accessory model, and the main reducer model inputs the rotating speed of the motor into the hydraulic motor model through the torque coupler model. The relationship model inside the wheel, the brake model and the main reducer model can be designed arbitrarily according to the physical mechanisms of the wheel, the brake model and the main reducer model, and the embodiment is not particularly limited.
The whole vehicle simulation system of the embodiment realizes the mixed configuration and function of the whole vehicle hydraulic system model and other energy system models. In order to verify the effectiveness of the hydraulic system model and the finished automobile simulation system, the finished automobile simulation system is subjected to simulation verification under the NEDC working condition in the embodiment. FIG. 6 is a schematic diagram of vehicle speed under the NEDC working condition, and FIG. 7 is a SOC variation diagram of a hydraulic accumulator model when the whole vehicle simulation system operates under the NEDC working condition. It can be seen that when the vehicle starts, the hydraulic accumulator of the hydraulic system supplies power to the hydraulic motor, and the SOC of the hydraulic accumulator model is reduced; when the vehicle operates in the deceleration stage under the NEDC condition (the portion marked by the dashed oval in fig. 6), the hydraulic system reversely rotates through the hydraulic motor, the braking energy is recovered, the hydraulic accumulator is charged, and the SOC of the hydraulic accumulator is increased (the portion marked by the dashed oval in fig. 7). The change rule accords with the reality, and the effectiveness of the hydraulic system simulation model and the whole vehicle simulation system of the embodiment is verified.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the technical solutions of the embodiments of the present invention.
Claims (6)
1. A method for constructing a hydraulic system model for a vehicle is characterized by comprising the following steps:
constructing a hydraulic motor model, a high-pressure hydraulic energy storage model, a low-pressure hydraulic energy storage model and a hydraulic accessory model in a simulation environment;
correlating the hydraulic motor model, the high-pressure hydraulic energy storage model, the low-pressure hydraulic energy storage model and the hydraulic accessory model according to a signal relation to form a hydraulic system model;
the construction process of the hydraulic motor model comprises the following steps:
constructing a calculation formula for calculating the output flow of the hydraulic motor model according to the control signal input into the hydraulic motor model and the motor rotating speed;
constructing a calculation formula of the torque loss of the hydraulic motor model according to the control signal;
constructing a calculation formula of the output torque of the hydraulic motor model according to the output flow and the torque loss;
wherein the control signal is representative of an operating state of the hydraulic motor;
the hydraulic motor model includes: the system comprises a hydraulic rotor model, a hydraulic actuator model and a flow calculation model;
the method for constructing a calculation formula for calculating the output flow of the hydraulic motor model according to the control signal input into the hydraulic motor model and the motor rotating speed comprises the following steps:
step one, according to a control signal input into the hydraulic motor model and the motor rotating speed, a calculation formula of the output flow of the hydraulic rotor model is established;
specifically, first, a theoretical flow rate of the hydraulic motor is constructed from the control signal and the motor speed input to the hydraulic motor model:
wherein the content of the first and second substances,
which represents the theoretical flow of the hydraulic motor,
a control signal representing a model of the hydraulic motor,
which represents the maximum displacement of the hydraulic motor,
represents the motor speed;
is the actual parameter of the hydraulic motor, and is considered to be known;
then, according to the theoretical flow, a calculation formula of the output flow of the hydraulic rotor model is constructed:
wherein, the first and the second end of the pipe are connected with each other,
represents the output flow of the hydraulic rotor model,
represents the volumetric efficiency of the hydraulic motor;
the method comprises the steps that three parameters, namely a control signal of a hydraulic motor model, the rotating speed of the hydraulic motor and the input pressure of the hydraulic motor model, are obtained by table look-up;
secondly, a calculation formula of the output flow of the hydraulic actuator model is constructed according to the control signal and the working time of the hydraulic actuator model;
specifically, firstly, a calculation formula of the increased flow of the hydraulic actuator model is constructed according to a control signal and working time:
wherein, the first and the second end of the pipe are connected with each other,
representing the incremental flow of the hydraulic actuator model,
the working time of the hydraulic actuator model is represented,
to represent
Control signal in time
The amount of change in the absolute value of (c),
representing the maximum flow of the hydraulic actuator model;
is an actual parameter of the hydraulic actuator and is considered to be known;
then, according to the increased flow and the leakage flow, a calculation formula of the output flow of the hydraulic actuator model is constructed:
wherein the content of the first and second substances,
representing the output flow of the hydraulic actuator model,
representing the leakage flow of the hydraulic actuator model;
obtaining by a known table look-up model, and looking up a table by using differential pressure at two ends of a hydraulic motor to obtain the leakage flow of the actuator model;
thirdly, according to the output flow of the hydraulic rotor model and the output flow of the hydraulic actuator, a calculation formula of the output flow of the hydraulic motor model is established:
wherein, the first and the second end of the pipe are connected with each other,
the output flow of the hydraulic motor model is represented,
represents the output flow of the hydraulic rotor model,
representing the output flow of the hydraulic actuator model;
the method for constructing the calculation formula of the torque loss of the hydraulic motor model according to the control signal comprises the following steps:
when the absolute value of the control signal is larger than a set threshold value, constructing a calculation formula of the torque loss of the hydraulic motor model according to a first torque loss caused by mechanical friction when the hydraulic motor operates;
when the absolute value of the control signal is smaller than or equal to the set threshold, constructing a calculation formula of the torque loss of the hydraulic motor model according to a second torque loss caused by oil viscous resistance when the hydraulic motor does not operate:
the method for constructing the calculation formula of the output torque of the hydraulic motor model according to the output flow and the torque loss specifically comprises the following steps of:
step one, according to the output flow direction of the hydraulic motor model, a calculation formula of the pressure drop of the hydraulic motor model is established:
wherein the content of the first and second substances,
representing the pressure drop of the hydraulic motor model,
is the input pressure of the hydraulic motor model,
a first positive pressure drop coefficient indicative of the hydraulic motor,
a second positive pressure drop coefficient indicative of the hydraulic motor,
a first negative pressure drop coefficient of the hydraulic motor is indicated,
a second negative pressure drop coefficient of the hydraulic motor is indicated,
the pressure drop ratio of the hydraulic motor is shown,
representing an output flow of the hydraulic motor model; wherein the content of the first and second substances,
are input parameters for the hydraulic motor model,
、
、
、
and
determined by the properties of the hydraulic motor itself, considered known;
step two, according to the pressure drop and the power flow direction of the hydraulic motor model, a calculation formula of the lossless torque of the hydraulic motor model is constructed:
wherein the content of the first and second substances,
representing a loss-free torque of the hydraulic motor model,
it is the mechanical efficiency of the hydraulic motor that,
a control signal representing a model of the hydraulic motor,
which represents the maximum displacement of the hydraulic motor,
a pressure drop of the hydraulic motor model is shown,
representing the power flow direction of the hydraulic motor model,
the control signal of the hydraulic motor model, the rotating speed of the hydraulic motor and the input pressure of the hydraulic motor model are obtained by looking up a table,
are the actual parameters of the hydraulic motor, which are considered known;
step three, according to the lossless torque and the torque loss under different control signals, constructing a calculation formula of the output torque of the hydraulic motor model:
wherein, the first and the second end of the pipe are connected with each other,
represents the output torque of the hydraulic motor model,
a control signal representing a model of the hydraulic motor,
representing a first torque loss caused by mechanical friction when the hydraulic motor is running,
representing a second torque loss caused by oil viscous resistance when the hydraulic motor is not operated;
the construction process of the high-pressure hydraulic accumulator model comprises the following steps:
building a calculation formula of the gas volume of the accumulated expansion of the hydraulic oil in the high-pressure hydraulic energy storage through the integration of the output flow of the high-pressure hydraulic energy storage model;
determining a calculation formula of the gas temperature of the high-pressure hydraulic energy storage model according to heat exchange between gas and a wall surface and between the gas and oil in the high-pressure hydraulic energy storage;
according to the gas volume and the gas temperature, a calculation formula of the output pressure of the high-pressure hydraulic energy storage model is constructed;
the construction process of the high-pressure hydraulic accumulator model comprises the following steps:
step one, constructing a calculation formula of gas volume of accumulated expansion of hydraulic oil in the high-pressure hydraulic energy storage through integration of output flow of the high-pressure hydraulic energy storage model;
wherein the content of the first and second substances,
indicating the gas volume of the accumulated expansion of the hydraulic oil in the high-pressure hydraulic accumulator,
representing the output flow of the high-pressure hydraulic accumulator model,trepresents time;
determining a calculation formula of the gas temperature of the high-pressure hydraulic energy storage model according to heat exchange between gas and a wall surface and between the gas and oil in the high-pressure hydraulic energy storage;
specifically, firstly, a calculation formula of heat loss power of a high-pressure hydraulic energy storage model is constructed:
（8）
wherein the content of the first and second substances,
represents the heat loss power of the high-pressure hydraulic accumulator model,
represents the heat transfer coefficient of the high-pressure hydraulic accumulator,
the effective area of the high-pressure hydraulic accumulator for heat dissipation is shown,
indicating the hydraulic oil temperature of the high-pressure hydraulic accumulator,
representing the gas temperature at the moment on the high-pressure hydraulic accumulator model,
、
and
as a practical reference for high-pressure hydraulic accumulatorsNumber, considered as a known amount;
then, according to the heat loss power, a calculation formula of the gas temperature of the high-pressure hydraulic energy storage model is constructed:
wherein the content of the first and second substances,
representing the current gas temperature of the high-pressure hydraulic accumulator model,
representing the adiabatic coefficient of the high-pressure hydraulic accumulator;
the gas temperature at the moment on the high-pressure hydraulic energy storage model is represented and stored by the delay module;
representing the output flow of the high-pressure hydraulic accumulator model,
indicating the gas volume of the accumulated expansion of the hydraulic oil in the high-pressure hydraulic accumulator,
represents the heat loss power of the high-pressure hydraulic accumulator model,
the heat capacity of the high-pressure hydraulic energy storage device is shown, wherein the heat capacity represents the heat exchange between the wall surface of the energy storage device and gas, and the heat capacity represents the heat exchange between the gas and oil;
thirdly, according to the gas volume and the gas temperature, a calculation formula of the output pressure of the high-pressure hydraulic energy storage model is established:
wherein, the first and the second end of the pipe are connected with each other,
represents the output pressure of the high-pressure hydraulic accumulator model,
representing the initial pressure of the high-pressure hydraulic accumulator,
representing the initial volume of the high-pressure hydraulic accumulator,
indicating the initial temperature of the gas of the high-pressure accumulator,
indicating the cumulative volume of expanding hydraulic oil in the high pressure accumulator,
representing the current gas temperature of the high-pressure hydraulic accumulator model,
、
and
is a preset value.
2. The method of claim 1, wherein the signal relationship comprises:
the output flow and the output pressure of the high-pressure hydraulic accumulator model are equal to the input flow and the input pressure of the hydraulic accessory model;
the output flow and the output pressure of the hydraulic accessory model are equal to the input flow and the input pressure of the hydraulic motor model;
and the output flow and the output pressure of the hydraulic motor model are equal to the input flow and the input pressure of the low-pressure hydraulic accumulator model.
3. The method of claim 1, wherein the hydraulic attachment model building process comprises the steps of:
and constructing a calculation formula of the output flow of the hydraulic accessory model according to the speed of the whole vehicle.
4. A simulation method of a vehicle hydraulic system is characterized by being applied to a vehicle hydraulic system model, wherein the hydraulic system model is constructed by the method according to any one of claims 1 to 3;
the simulation method comprises the following steps:
and determining the optimal solution of the output torque according to each calculation equation constructed in the hydraulic system model, and taking the optimal solution as the output of the hydraulic system model.
5. A whole vehicle simulation system is characterized by comprising: the hydraulic system model, engine model, clutch model, transmission model, and torque coupler model of claim 4;
in the whole vehicle simulation process, the output torque of the engine model passes through the clutch model and the transmission model and then is input into the torque coupler model; the torque coupler model is used for coupling and outputting the torque from the hydraulic system model and the engine model.
6. The system of claim 5, further comprising: an Electronic Control Unit (ECU) model;
in the whole vehicle simulation process, the ECU model is used for respectively sending control signals to the vehicle hydraulic system model and the engine model according to the running condition of the whole vehicle, and the control signals respectively control the running states of the hydraulic motor and the engine.
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