CN112460241B  Design method for inhibiting oil mixing power loss of transmission system  Google Patents
Design method for inhibiting oil mixing power loss of transmission system Download PDFInfo
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 CN112460241B CN112460241B CN202011052438.6A CN202011052438A CN112460241B CN 112460241 B CN112460241 B CN 112460241B CN 202011052438 A CN202011052438 A CN 202011052438A CN 112460241 B CN112460241 B CN 112460241B
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 F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
 F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
 F16H—GEARING
 F16H57/00—General details of gearing
 F16H57/04—Features relating to lubrication or cooling or heating
 F16H57/0409—Features relating to lubrication or cooling or heating characterised by the problem to increase efficiency, e.g. by reducing splash losses

 F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
 F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
 F16H—GEARING
 F16H41/00—Rotary fluid gearing of the hydrokinetic type
 F16H41/04—Combined pumpturbine units

 F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
 F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
 F16H—GEARING
 F16H41/00—Rotary fluid gearing of the hydrokinetic type
 F16H41/24—Details
 F16H41/30—Details relating to venting, lubrication, cooling, circulation of the cooling medium

 F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
 F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
 F16H—GEARING
 F16H57/00—General details of gearing
 F16H57/08—General details of gearing of gearings with members having orbital motion

 F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
 F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
 F16H—GEARING
 F16H57/00—General details of gearing
 F16H57/08—General details of gearing of gearings with members having orbital motion
 F16H2057/087—Arrangement and support of friction devices in planetary gearings, e.g. support of clutch drums, stacked arrangements of friction devices
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Abstract
The invention discloses a design method for inhibiting oil stirring power loss of a transmission system, which comprises the following steps: step 1, obtaining the oil mixing power loss of each component in the comprehensive transmission system at different rotating speeds through an oil mixing power loss test, and selecting more than two components which are arranged at the front in the oil mixing power loss of the comprehensive transmission system from large to small for power suppression; the selected components are a planetary speed change mechanism and a hydraulic element, wherein the hydraulic element comprises a steering hydraulic coupler and a hydraulic retarder; and 2, inhibiting the oil stirring power loss of the member selected in the step 1, wherein the inhibiting method comprises the following steps: the minimum distance between the parts with the maximum speed difference in the planetary speed change mechanism is increased, the leakage loss of a liquid filling control valve of a hydraulic element is reduced, and a sealing ring material with a small friction coefficient is adopted. The invention can realize the oil mixing power loss inhibition of the comprehensive transmission system which is changed from one dimension to multiple dimensions and expanded from point to domain, and is beneficial to improving the design level of the vehicle running performance and the fuel economy.
Description
Technical Field
The invention belongs to the technical field of tracked vehicles, and particularly relates to a design method for inhibiting oil mixing power loss of a transmission system.
Background
The oil stirring power loss of the comprehensive transmission system is an important factor for restricting the improvement of the transmission efficiency, the noload oil stirring power loss is large, the heat productivity of the system is inevitably large, the burden of a matched cooling auxiliary system is large, the overall efficiency and performance index of the transmission system are difficult to improve, and the overall efficiency, the economy and the reliability of the whole vehicle are directly influenced. Therefore, the oil stirring power loss value of the comprehensive transmission system has important influence on the fuel economy of the vehicle, and the method is important for designing and checking the comprehensive transmission system.
The comprehensive transmission system integrates mechanical, electronic, hydraulic and other components, is complex in structural composition, and mutually couples working boundary conditions for constructing oil mixing power loss, so that a scientific design method for calculating the oil mixing power loss in a system level is lacked in the industry at present.
Disclosure of Invention
In view of the above, the invention provides a design method for suppressing oil mixing power loss of a transmission system, which can realize the oil mixing power loss suppression of the comprehensive transmission system by converting from one dimension to multiple dimensions and expanding from a point to a domain, and is beneficial to improving the design level of the vehicle driving performance and the fuel economy.
The invention is realized by the following technical scheme:
a design method for inhibiting oil stirring power loss of a transmission system comprises the following specific steps:
and 2, inhibiting the oil stirring power loss of the member selected in the step 1, wherein the inhibiting method comprises the following steps: the minimum distance between the parts with the maximum speed difference in the planetary speed change mechanism is increased, the leakage loss of a liquid filling control valve of a hydraulic element is reduced, and a sealing ring material with a small friction coefficient is adopted.
Further, polyimide is adopted as the material of the sealing ring.
Further, the relationship between the minimum distance between the parts with the maximum speed difference in the selected component and the oil churning power loss in the step 2 is calculated as follows:
under the noload working condition of the comprehensive transmission system, lubricating oil flows out of each lubricating point in the planetary speed change mechanism, and is in an inertial flow state under the rotation action of a lubricating part; the lubricating oil is mixed with air in a box body of the planetary speed change mechanism to form a gasliquid twophase flow state, and a flow field of the gasliquid twophase flow is a nonuniformly distributed flow field; the distribution of the lubricating oil changes along with the change of the distance between the rotating center of the transmission shaft system and the inner wall of the box body;
the method comprises the following steps of firstly, establishing a gasliquid twophase mixed flow field model by taking the rotation center of a transmission shaft system and the inner wall of a box body as reference standards:
the lubricating oil is set to be diffused to the circumferential direction under the action of centrifugal force, so that the fluid density of the gasliquid twophase mixed flow field is as follows:
in the formula, ρ_{0}Fluid density, rho, of a gasliquid twophase mixed flow field_{air}Is the air density, p_{oil}The density of the lubricating oil is shown, x is the distance from any point of the lubricating oil in the gasliquid twophase mixed flow field to the wall surface of the lubricating part, and v is the linear velocity of the wall surface of the lubricating part;
therefore, it is known that the distribution of the lubricating oil in the gasliquid twophase mixed flow field is related to the distance from the wall surface of the lubricating part and the linear velocity of the wall surface of the lubricating part, and as the linear velocity of the wall surface of the lubricating part increases, the closer to the wall surface of the lubricating part, the less the distribution of the lubricating oil;
secondly, in an actual working condition, because the gasliquid twophase mixed flow field is positioned in a closed environment in the planetary speed change mechanism, the two sides of the gasliquid twophase mixed flow field are respectively the wall surfaces of two lubricating parts in the planetary speed change mechanism; therefore, the threedimensional flow space of the gasliquid twophase mixed flow field is simplified into twodimensional fluid distribution between the wall surfaces of two lubricating parts, and the calculation formula of the fluid density of the gasliquid twophase mixed flow field in the formula (1) is converted into:
in the formula, v_{1}、v_{2}Linear velocity, x, of the walls of two lubricated parts, respectively_{1}、x_{2}Respectively the distance between any point of lubricating oil in the gasliquid twophase mixed flow field and the wall surfaces of the two lubricating parts;
obtaining the fluid viscosity mu of the gasliquid twophase mixed flow field according to the similarity of the fluid viscosity and the physical properties of the fluid density_{0}The calculation model is:
in the formula, mu_{air}Is air viscosity, μ_{oil}Is the viscosity of the lubricating oil;
selecting any one of the two lubricating parts as a research object, and establishing a resistance model for the frictional resistance between the wall surface of the selected lubricating part and the fluid of the gasliquid twophase mixed flow field by a flat boundary layer calculation method; the frictional resistance F is:
wherein, C_{f}For the fluid frictional resistance, the expression is:
wherein Re is a Reynolds number, v_{0}The linear velocity of the fluid of the gasliquid twophase mixed flow field relative to the selected lubricating part is defined as B, the contact width of the wall surface of the selected lubricating part and the fluid of the gasliquid twophase mixed flow field is defined as B, and the contact length of the wall surface of the selected lubricating part and the fluid of the gasliquid twophase mixed flow field is defined as L.
Fourthly, according to a formula (6), obtaining the oil stirring power loss P of the lubricated parts selected in the third step_{1}，P_{1}The expression of (a) is as follows:
P_{1}＝Fv_{0}formula (7)
According to the formula (7), under the noload working condition, the oil stirring power loss of the lubricating part selected in the third step is related to the frictional resistance F, and further related to the fluid density rho of the gasliquid twophase mixed flow field_{0}With respect to the distance between two lubricated parts; the smaller the distance between the two lubricated parts is, the greater the oil stirring power loss of the lubricated parts is.
Further, the calculation process of the relationship between the leakage loss of the liquid filling control valve of the hydraulic element and the oil stirring power loss in the step 2 is as follows:
the liquid filling control valve leaks, and oil enters the hydraulic element and is mixed with air in the hydraulic element to form a gasliquid twophase mixed flow field; at this time, the hydraulic element is in an oilfilled state;
oil mixing power loss P of hydraulic element in oilfilled state_{2}The calculation formula of (a) is as follows:
P_{2}＝ρ_{0}'gλn^{3}D^{5}formula (8)
In the formula, ρ_{0}The two impellers of the hydraulic element are respectively a fixed wheel and a movable wheel of a hydraulic speed reducer or a pump wheel and a turbine of a hydraulic coupler; d is the effective duty cycle circle diameter, and λ is the torque coefficient, which can be obtained from the oil churning power loss of Table 1, and the expression for λ is as follows:
in the formula, n_{B}The pump wheel speed of the fluid coupling or the fixed wheel speed of the fluid retarder, n_{T}The rotational speed of a turbine of the hydraulic coupler or the rotational speed of a driving wheel of the hydraulic retarder; if n is_{B}≠0,If n is_{B}0, λ is constant;
let δ be ρ_{0}'gλD^{5}Then, equation (8) is changed to:
P_{2}＝δn^{3}formula (10)
According to the formula (10), the oil churning power loss of the hydraulic element in the oilfilled state is related to the relative rotating speed between the impellers, namely the oil churning power loss of the hydraulic speed reducer is related to the relative rotating speed between the movable wheel and the fixed wheel, and the oil churning power loss of the hydraulic coupler is related to the relative rotating speed between the pump wheel and the turbine wheel; the less oil leakage of the liquid filling control valve, the smaller the relative rotating speed between the impellers, and the smaller the oil stirring power loss.
Further, the calculation process of the relationship between the friction coefficient of the sealing ring material and the oil stirring power loss in the step 2 is as follows:
firstly, analyzing motion law influence factors, namely calculating the oil stirring power loss between two binding surfaces with relative motion in a relative highspeed motion space according to a motion state;
the rotary sealing knotThe structure includes: the rotary shaft, the oil distribution sleeve and the sealing ring; an annular groove is processed on the outer circumferential surface of the rotating shaft; the sealing ring is arranged in the annular groove; the oil distribution sleeve is sleeved outside the rotating shaft, and a gap is reserved between the inner circumferential surface of the oil distribution sleeve and the outer circumferential surface of the rotating shaft; the outer circumferential surface of the sealing ring is an AB surface, the inner circumferential surface of the sealing ring is a CD surface, and the two end surfaces of the sealing ring are respectively an AD surface and a CB surface; wherein, the AB surface of the sealing ring is in contact with the inner circumferential surface of the oil distribution sleeve; the BC surface of the sealing ring is in fit contact with the wall surface of the annular groove on the rotating shaft; the sealing oil of the comprehensive transmission system is filled in the annular groove on the rotating shaft, and the oil pressure of the sealing oil is p_{0}Under the action of the pressure of the sealing oil, frictional resistance F is generated between the AB surface of the sealing ring and the inner circumferential surface of the oil distribution sleeve_{AB}Frictional resistance F is generated between the CB surface of the seal ring and the wall surface of the annular groove of the rotary shaft_{CB}；
When F is present_{CB}>F_{AB}When the oil stirring device is used, the sealing ring and the rotating shaft rotate together, and the oil stirring power loss comes from frictional resistance F_{AB}；
F_{AB}＝p_{0}2πr_{1}Hf_{1}Formula (11)
In the formula, r_{1}Is the outer diameter of the seal ring, H is the axial length of the seal ring, f_{1}The friction coefficient between the sealing ring and the oil distribution sleeve is defined as the friction coefficient;
when F is present_{CB}<F_{AB}When the oil mixing machine is used, the sealing ring and the oil distribution sleeve rotate together, and the oil mixing power loss comes from frictional resistance F_{CB}；
In the formula, r_{1}Is the outer diameter of the sealing ring, r_{2}The inner diameter of the seal ring is delta is the clearance between the outer circumferential surface of the rotating shaft and the inner circumferential surface of the oil distribution sleeve, f_{2}The coefficient of friction between the sealing ring and the wall surface of the annular groove of the rotating shaft;
when F is present_{CB}＝F_{AB}When the motion state of the sealing ring is in a critical state, the sealing ring can rotate along with the rotationThe shaft or the oil distribution sleeve rotates, and when the sealing ring rotates along with the rotating shaft, the oil stirring power loss comes from frictional resistance F_{AB}(ii) a When the sealing ring rotates along with the oil distribution sleeve, the oil stirring power loss comes from frictional resistance F_{CB}；
Judging the motion state of the seal ring according to the motion coefficient sigma, wherein the motion coefficient sigma is expressed as follows:
according to the formula (13), since the machining accuracy of the rotary shaft and the oil distribution sleeve is the same, the friction coefficient f_{1}＝f_{2}The motion coefficient sigma is only related to the geometric dimension and the fit clearance of the sealing ring, the geometric dimension and the fit clearance of the sealing ring are substituted into a formula (13), sigma is calculated, and the calculation result shows that the sigma is far less than 1, so that the sealing ring and the oil distribution sleeve are judged to rotate together, and the power loss of the sealing ring comes from the frictional resistance F_{CB}；
Secondly, the friction resistance influencing factor analysis is carried out, namely, the friction coefficient f in the formula (12) is determined through experiments_{2}；
The formula (12) deduces the expression of the friction torque M applied to the sealing ring as follows:
wherein D is frictional resistance F_{CB}The value of the friction torque M can be obtained by tests, which are: selecting more than two sealing ring samples with the same geometric dimension but different materials, performing a contrast test, and obtaining the friction torque M borne by the sealing ring through a torquemeter test in the test process;
the friction coefficient f can be obtained by substituting the test result, i.e., the value of the friction torque M, into the formula (14)_{2}The change rule of the friction coefficient change and the friction torque of the sealing rings made of different materials is obtained according to the change trend as follows:
thirdly, calculating the oil stirring power loss P of the sealing ring according to the formula (15)_{3}The expression is as follows:
in the formula, n is the rotating speed of the rotating shaft;
according to the formula (16), the oil churning power loss of the sealing ring is related to the friction coefficient of the material, and the smaller the friction coefficient of the material of the sealing ring is, the smaller the oil churning power loss is.
Has the advantages that:
1. the invention provides a design method for inhibiting the oil stirring power loss of a comprehensive transmission system from one dimension to multidimension conversion and from point to domain expansion for components with larger proportion in the oil stirring power loss in the comprehensive transmission system, namely a planetary speed change mechanism and a hydraulic element.
2. In the design of a comprehensive transmission system, the oil mixing power loss inhibition is realized by three multidimensional design methods, namely (1) the minimum distance between two lubrication parts with the maximum speed difference is increased; (2) the leakage of a liquid filling control valve of the hydraulic element is reduced; (3) a sealing ring material (polyimide) with a small friction coefficient is adopted; the invention inhibits the oil mixing power loss of internal components of the transmission system from multiple dimensions, and specifically adopts measures to inhibit the oil mixing power loss, thereby effectively improving the system efficiency and improving the economic performance of vehicle fuel.
3. The method adopts a calculation model of the oil mixing power loss of the comprehensive transmission system and a test verification result as a basis, is not only applied to the comprehensive transmission system, but also provides a reference for a design method for inhibiting the oil mixing power loss of the transmission system with different modes.
Drawings
FIG. 1 is a proportional relationship of noload losses of various components in an integrated transmission system;
FIG. 2 is a lubricating oil density distribution within a flow field of a twophase gasliquid flow;
FIG. 3 is a relationship between oil churning power loss and distance between two lubricated parts;
FIG. 4 is a schematic view of the sealing ring under force.
Detailed Description
The invention is described in detail below by way of example with reference to the accompanying drawings.
The embodiment provides a design method for inhibiting oil stirring power loss of a transmission system, which comprises the following specific steps:
wherein the oil stirring power loss of the integrated transmission system comprises: the power required by the hydraulic system for supplying lubricating oil, operating oil and compensating oil to the system, the power lost by the meshing and oil stirring of a gear shafting, the power lost by a friction element, and the power lost by the friction of a sealing element and a hydraulic element;
the process of the oil stirring power loss test of the comprehensive transmission system is as follows:
because the rotating speed of each component of the comprehensive transmission system under the highest gear is highest, the noload test working condition when the input rotating speeds of the comprehensive transmission system under the highest gear are 1800r/min, 2000r/min and 2200r/min work is selected, the input rotating speeds of the system are set in a test, the input rotating speeds of different components are obtained through the calculation of the transmission ratio, and the noload oil stirring power loss of each component is further obtained; through comparison, three components with the proportion of oil stirring power loss in the system ranked from large to small are selected for inhibiting the oil stirring power loss; the oil stirring power loss conditions of all the components at the highest gear and different rotating speeds are shown in the table 1;
TABLE 1 comparison of Noload Stir oil Power losses for each component
As can be seen from table 1, when the input rotation speed of this embodiment is 2199r/min, the idle load maximum churning power loss value and the maximum total churning power loss of each component are the largest, as shown in fig. 1, the calculated idle load loss ratio of the planetary transmission mechanism is the largest, which is 53.50/158.6733.72%, and then the ratio of the idle load loss ratio of the planetary transmission mechanism is 25.56/158.6716.11%, and the ratio of the idle load loss ratio of the planetary transmission mechanism is 3.65/158.6714.07%; therefore, the planetary speed change mechanism and hydraulic elements (namely, the steering hydraulic coupler and the hydraulic retarder) are selected for oil mixing power loss suppression;
and 2, inhibiting the oil stirring power loss of the planetary speed change mechanism and the hydraulic element selected in the step 1, wherein the inhibiting method comprises the following steps: the minimum distance between parts with the maximum speed difference in the planetary speed change mechanism is increased, leakage loss of a hydraulic element liquid filling control valve is reduced, and a sealing ring material with a small friction coefficient, such as polyimide, is adopted;
(1) the minimum distance between the parts with the maximum speed difference in the planetary speed change mechanism is increased, so that the oil stirring power loss between the parts of the comprehensive transmission system is inhibited;
under the noload working condition of the comprehensive transmission system, lubricating oil flows out of each lubricating point in the planetary speed change mechanism, and is in an inertial flow state under the rotation action of a lubricating part; the lubricating oil is mixed with air in a box body of the planetary speed change mechanism to form a gasliquid twophase flow state, and a flow field of the gasliquid twophase flow is a nonuniformly distributed flow field; the distribution of the lubricating oil changes along with the change of the distance between the rotating center of the transmission shaft system and the inner wall of the box body;
the method comprises the following steps of firstly, establishing a gasliquid twophase mixed flow field model by taking the rotation center of a transmission shaft system and the inner wall of a box body as reference standards:
the lubricating oil is set to be diffused to the circumferential direction under the action of centrifugal force, so that the fluid density of the gasliquid twophase mixed flow field is as follows:
in the formula, ρ_{0}Fluid density, rho, of a gasliquid twophase mixed flow field_{air}Is the air density, p_{oil}In order to obtain the density of lubricating oil, x is the distance (mm) from any point of the lubricating oil in the gasliquid twophase mixed flow field to the wall surface of the lubricating part, and v is the linear velocity (m/s) of the wall surface of the lubricating part;
therefore, it can be known that the distribution of the lubricating oil in the gasliquid twophase mixed flow field is related to the distance from the wall surface of the lubricating part and the linear velocity of the wall surface of the lubricating part, and as the linear velocity of the wall surface of the lubricating part increases, the closer the wall surface of the lubricating part is, the less the distribution of the lubricating oil is, see fig. 2;
secondly, in an actual working condition, because the gasliquid twophase mixed flow field is positioned in a closed environment in the planetary speed change mechanism, the two sides of the gasliquid twophase mixed flow field are respectively the wall surfaces of two lubricating parts in the planetary speed change mechanism; therefore, the threedimensional flow space of the gasliquid twophase mixed flow field can be simplified into twodimensional fluid distribution between the wall surfaces of two lubricating parts, and the calculation formula of the fluid density of the gasliquid twophase mixed flow field in the formula (1) is converted into:
in the formula, v_{1}、v_{2}Linear velocity (m/s), x, of the walls of two lubricated parts, respectively_{1}、x_{2}Respectively the distance (mm) from any point of lubricating oil in the gasliquid twophase mixed flow field to the wall surfaces of the two lubricating parts;
according to the similarity of the physical properties of the fluid viscosity and the fluid density, the fluid viscosity mu of the gasliquid twophase mixed flow field can be obtained_{0}The calculation model is:
in the formula, mu_{air}Is air viscosity, μ_{oil}Is the viscosity of the lubricating oil;
selecting any one of the two lubricating parts as a research object, and establishing a resistance model for the frictional resistance between the wall surface of the selected lubricating part and the fluid of the gasliquid twophase mixed flow field by a flat boundary layer calculation method; the frictional resistance F is:
wherein, C_{f}For the fluid frictional resistance, the expression is:
where Re is the Reynolds number (indicating the degree of turbulence in the fluid flow, with greater indicating greater turbulence), and v_{0}The linear velocity of the fluid of the gasliquid twophase mixed flow field relative to the selected lubricating part is defined as B, the contact width of the wall surface of the selected lubricating part and the fluid of the gasliquid twophase mixed flow field is defined as B, and the contact length of the wall surface of the selected lubricating part and the fluid of the gasliquid twophase mixed flow field is defined as L.
Fourthly, according to a formula (6), obtaining the oil stirring power loss P of the lubricated parts selected in the third step_{1}，P_{1}The expression of (a) is as follows:
P_{1}＝Fv_{0}formula (7)
According to the formula (7), under the noload working condition, the oil stirring power loss of the lubricating part selected in the third step is related to the frictional resistance F, and further related to the fluid density rho of the gasliquid twophase mixed flow field_{0}With respect to the distance between two lubricated parts; particularly, the distance between two lubricating parts with higher relative rotation speed difference is smaller, and the oil stirring power loss is larger; referring to FIG. 3, when the distance between two lubricated parts (i.e., x)_{1}+x_{2}) When the diameter is less than 0.5mm, the oil film shearing function is realized, so that the oil stirring power loss is greatly increased; therefore, in the integrated transmission system, the minimum distance between two lubrication parts with the relative maximum speed difference is larger than 1mm, if there is enough space inside the integrated transmission system, and the oil stirring power loss of the integrated transmission system is greatly reduced after the minimum distance is larger than 2 mm.
(2) The oil mixing power loss of the hydraulic element is inhibited by reducing the leakage of the hydraulic element liquid filling control valve;
the hydraulic coupler and the hydraulic retarder are hydraulic elements in the comprehensive transmission system, and the oil stirring power loss of the elements in the hydraulic system is more complicated to calculate due to the complex shape and the complex oil charging state of a cascade inside the hydraulic elements; in the comprehensive transmission system, the hydraulic speed reducer is divided into a fixed wheel and a movable wheel, and under all working states, a large and fixed relative speed difference exists between the fixed wheel and the movable wheel; the hydraulic coupler and the hydraulic reducer have basically the same structure, and in an oilfilled state, the relative speed difference between a pump impeller and a turbine of the hydraulic coupler changes along with the change of a working state;
the liquid filling control valve leaks, and oil enters the hydraulic element and is mixed with air in the hydraulic element to form a gasliquid twophase mixed flow field; at this time, the hydraulic element is in an oilfilled state;
oil mixing power loss P of hydraulic element in oilfilled state_{2}The calculation formula of (a) is as follows:
P_{2}＝ρ_{0}'gλn^{3}D^{5}formula (8)
In the formula, ρ_{0}' is a gasliquid two inside a hydraulic elementThe fluid density of the phase mixing flow field, g is a constant, n is the relative rotating speed between two impellers of a hydraulic element, and the two impellers of the hydraulic element are respectively a fixed wheel and a driving wheel of a hydraulic speed reducer or a pump wheel and a turbine wheel of a hydraulic coupler; d is the effective duty cycle circle diameter, and λ is the torque coefficient, which can be obtained from the oil churning power loss of Table 1, and the expression for λ is as follows:
in the formula, n_{B}The pump wheel speed of the fluid coupling or the fixed wheel speed of the fluid retarder, n_{T}The rotational speed of a turbine of the hydraulic coupler or the rotational speed of a driving wheel of the hydraulic retarder; if n is_{B}≠0,If n is_{B}0, λ is constant;
let δ be ρ_{0}'gλD^{5}Then, equation (8) is changed to:
P_{2}＝δn^{3}formula (10)
According to the formula (10), the oil churning power loss of the hydraulic element in the oilfilled state is related to the relative rotating speed between the impellers, namely the oil churning power loss of the hydraulic speed reducer is related to the relative rotating speed between the movable wheel and the fixed wheel, and the oil churning power loss of the hydraulic coupler is related to the relative rotating speed between the pump wheel and the turbine wheel; the leakage of the liquid filling control valve is less, the relative rotating speed between the impellers is smaller, the oil stirring power loss is smaller, the relative rotating speed between the impellers is larger, the oil stirring power loss is increased more quickly, and therefore the leakage of the liquid filling control valve is an effective measure for inhibiting the oil stirring power loss.
(3) The power loss of the rotary sealing element is restrained by adopting a sealing ring material with a smaller friction coefficient, such as polyimide;
because a plurality of rotary sealing structures exist in the comprehensive transmission system, the rotary sealing structure has high pressure and high linear speed, and certain oil stirring power loss also exists; establishing a dynamic sealing ring power loss model according to the motion rule influence factors and the frictional resistance influence factors, and calculating to obtain the relation between the friction coefficient of the material sealing ring and the oil stirring power loss;
firstly, analyzing motion law influence factors, namely calculating the oil stirring power loss between two binding surfaces with relative motion in a relative highspeed motion space according to a motion state;
referring to fig. 4, the rotary seal structure includes: the rotary shaft, the oil distribution sleeve and the sealing ring; an annular groove is processed on the outer circumferential surface of the rotating shaft; the sealing ring is arranged in the annular groove; the oil distribution sleeve is sleeved outside the rotating shaft, and a gap is reserved between the inner circumferential surface of the oil distribution sleeve and the outer circumferential surface of the rotating shaft; the outer circumferential surface of the sealing ring is an AB surface, the inner circumferential surface of the sealing ring is a CD surface, and the two end surfaces of the sealing ring are respectively an AD surface and a CB surface; wherein, the AB surface of the sealing ring is in contact with the inner circumferential surface of the oil distribution sleeve; the BC surface of the sealing ring is in fit contact with the wall surface of the annular groove on the rotating shaft; the sealing oil of the comprehensive transmission system is filled in the annular groove on the rotating shaft, and the oil pressure of the sealing oil is p_{0}Under the action of the pressure of the sealing oil, frictional resistance F is generated between the AB surface of the sealing ring and the inner circumferential surface of the oil distribution sleeve_{AB}Frictional resistance F is generated between the CB surface of the seal ring and the wall surface of the annular groove of the rotary shaft_{CB}；
When F is present_{CB}>F_{AB}When the oil stirring device is used, the sealing ring and the rotating shaft rotate together, and the oil stirring power loss comes from frictional resistance F_{AB}；
F_{AB}＝p_{0}2πr_{1}Hf_{1}Formula (11)
In the formula, r_{1}Is the outer diameter of the seal ring, H is the axial length of the seal ring, f_{1}The friction coefficient between the sealing ring and the oil distribution sleeve is defined as the friction coefficient;
when F is present_{CB}<F_{AB}When the oil mixing machine is used, the sealing ring and the oil distribution sleeve rotate together, and the oil mixing power loss comes from frictional resistance F_{CB}；
In the formula, r_{1}Is the outer diameter of the sealing ring, r_{2}The inner diameter of the seal ring is delta is the clearance between the outer circumferential surface of the rotating shaft and the inner circumferential surface of the oil distribution sleeve, f_{2}The coefficient of friction between the sealing ring and the wall surface of the annular groove of the rotating shaft;
when F is present_{CB}＝F_{AB}When the sealing ring rotates along with the rotating shaft, the oil stirring power loss comes from frictional resistance F_{AB}(ii) a When the sealing ring rotates along with the oil distribution sleeve, the oil stirring power loss comes from frictional resistance F_{CB}；
Judging the motion state of the seal ring according to the motion coefficient sigma, wherein the motion coefficient sigma is expressed as follows:
according to the formula (13), the motion state of the sealing ring is related to the friction coefficient, the size of the sealing ring and the fit clearance, and the friction coefficient f is obtained because the mating part of the sealing ring is a metal part (the mating part comprises a rotating shaft and an oil distribution sleeve) and the machining precision of the rotating shaft and the oil distribution sleeve is the same_{1}＝f_{2}The motion coefficient sigma is only related to the geometric dimension and the fit clearance of the sealing ring, the geometric dimension and the fit clearance of the sealing ring are substituted into a formula (13), sigma is calculated, and the calculation result shows that the sigma is far less than 1, so that the sealing ring and the oil distribution sleeve are judged to rotate together, and the power loss of the sealing ring comes from the frictional resistance F_{CB}；
Secondly, the friction resistance influencing factor analysis is carried out, namely, the friction coefficient f in the formula (12) is determined through experiments_{2}；
The formula (12) deduces the expression of the friction torque M applied to the sealing ring as follows:
wherein D is frictional resistance F_{CB}The value of the friction torque M can be obtained by tests, which are: selecting more than two sealing ring samples with the same geometric dimension but different materials, performing a contrast test, and obtaining the friction torque M borne by the sealing ring through a torquemeter test in the test process;
the friction coefficient f can be obtained by substituting the test result, i.e., the value of the friction torque M, into the formula (14)_{2}The change rule of the friction coefficient change and the friction torque of the sealing rings made of different materials is obtained according to the change trend as follows:
thirdly, calculating the oil stirring power loss P of the sealing ring according to the formula (15)_{3}The expression is as follows:
in the formula, n is the rotating speed of the rotating shaft;
according to the formula (16), the oil stirring power loss of the sealing ring is related to the friction coefficient of the material, and the sealing ring material with a small friction coefficient is selected, so that the oil stirring power loss can be reduced; the test proves that the friction coefficient of the sealing ring of the polyimide material is the minimum, so that the oil stirring power loss of the system can be reduced by selecting the polyimide sealing ring.
In summary, the above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (5)
1. A design method for inhibiting oil stirring power loss of a transmission system is characterized by comprising the following specific steps:
step 1, obtaining oil stirring power loss of each component in the comprehensive transmission system at different rotating speeds through an oil stirring power loss test, wherein each component in the comprehensive transmission system is as follows: the system comprises a planetary speed change mechanism, a hydraulic element, a hydraulic torque converter, a fan hydraulic coupler, a 120 pump motor, a dynamic seal, a front transmission, a bus bar and a hydraulic pump set; the hydraulic element comprises a steering hydraulic coupler and a hydraulic retarder; selecting a planetary speed change mechanism and a hydraulic element which are arranged at the front in the oil stirring power loss of the comprehensive transmission system from large to small for power suppression;
and 2, inhibiting the oil stirring power loss of the member selected in the step 1, wherein the inhibiting method comprises the following steps: the minimum distance between the parts with the maximum speed difference in the planetary speed change mechanism is increased, the leakage loss of a liquid filling control valve of a hydraulic element is reduced, and a sealing ring material with a small friction coefficient is adopted.
2. The design method for suppressing oil churning power loss of the transmission system according to claim 1, wherein the material of the seal ring is polyimide.
3. The method of claim 1, wherein the relationship between the minimum distance between the parts with the maximum speed difference in the member selected in step 2 and the churning power loss is calculated as follows:
under the noload working condition of the comprehensive transmission system, lubricating oil flows out of each lubricating point in the planetary speed change mechanism, and is in an inertial flow state under the rotation action of a lubricating part; the lubricating oil is mixed with air in a box body of the planetary speed change mechanism to form a gasliquid twophase flow state, and a flow field of the gasliquid twophase flow is a nonuniformly distributed flow field; the distribution of the lubricating oil changes along with the change of the distance between the rotating center of the transmission shaft system and the inner wall of the box body;
the method comprises the following steps of firstly, establishing a gasliquid twophase mixed flow field model by taking the rotation center of a transmission shaft system and the inner wall of a box body as reference standards:
the lubricating oil is set to be diffused to the circumferential direction under the action of centrifugal force, so that the fluid density of the gasliquid twophase mixed flow field is as follows:
in the formula, ρ_{0}Fluid density, rho, of a gasliquid twophase mixed flow field_{air}Is the air density, p_{oil}The density of the lubricating oil is shown, x is the distance from any point of the lubricating oil in the gasliquid twophase mixed flow field to the wall surface of the lubricating part, and v is the linear velocity of the wall surface of the lubricating part;
therefore, it is known that the distribution of the lubricating oil in the gasliquid twophase mixed flow field is related to the distance from the wall surface of the lubricating part and the linear velocity of the wall surface of the lubricating part, and as the linear velocity of the wall surface of the lubricating part increases, the closer to the wall surface of the lubricating part, the less the distribution of the lubricating oil;
secondly, in an actual working condition, because the gasliquid twophase mixed flow field is positioned in a closed environment in the planetary speed change mechanism, the two sides of the gasliquid twophase mixed flow field are respectively the wall surfaces of two lubricating parts in the planetary speed change mechanism; therefore, the threedimensional flow space of the gasliquid twophase mixed flow field is simplified into twodimensional fluid distribution between the wall surfaces of two lubricating parts, and the calculation formula of the fluid density of the gasliquid twophase mixed flow field in the formula (1) is converted into:
in the formula, v_{1}、v_{2}Linear velocity, x, of the walls of two lubricated parts, respectively_{1}、x_{2}Respectively the distance between any point of lubricating oil in the gasliquid twophase mixed flow field and the wall surfaces of the two lubricating parts;
obtaining the fluid viscosity mu of the gasliquid twophase mixed flow field according to the similarity of the fluid viscosity and the physical properties of the fluid density_{0}The calculation model is:
in the formula, mu_{air}Is air viscosity, μ_{oil}Is the viscosity of the lubricating oil;
selecting any one of the two lubricating parts as a research object, and establishing a resistance model for the frictional resistance between the wall surface of the selected lubricating part and the fluid of the gasliquid twophase mixed flow field by a flat boundary layer calculation method; the frictional resistance F is:
wherein, C_{f}For the fluid frictional resistance, the expression is:
wherein Re is a Reynolds number, v_{0}The linear velocity of the fluid of the gasliquid twophase mixed flow field relative to the selected lubricating part is defined as B, the contact width of the wall surface of the selected lubricating part and the fluid of the gasliquid twophase mixed flow field is defined as L, and the contact length of the wall surface of the selected lubricating part and the fluid of the gasliquid twophase mixed flow field is defined as L;
fourthly, according to a formula (6), obtaining the oil stirring power loss P of the lubricated parts selected in the third step_{1}，P_{1}The expression of (a) is as follows:
P_{1}＝Fv_{0}formula (7)
According to the formula (7), the third step is carried out under noload conditionThe oil stirring power loss of the selected lubricating parts is related to the frictional resistance F, and further related to the fluid density rho of the gasliquid twophase mixed flow field_{0}With respect to the distance between two lubricated parts; the smaller the distance between the two lubricated parts is, the greater the oil stirring power loss of the lubricated parts is.
4. The design method for inhibiting the oil churning power loss of the transmission system according to claim 1, wherein the relation between the leakage of the hydraulic filling control valve of the hydraulic element and the oil churning power loss in the step 2 is calculated as follows:
the liquid filling control valve leaks, and oil enters the hydraulic element and is mixed with air in the hydraulic element to form a gasliquid twophase mixed flow field; at this time, the hydraulic element is in an oilfilled state;
oil mixing power loss P of hydraulic element in oilfilled state_{2}The calculation formula of (a) is as follows:
P_{2}＝ρ_{0}'gλn^{3}D^{5}formula (8)
In the formula, ρ_{0}The two impellers of the hydraulic element are respectively a fixed wheel and a movable wheel of a hydraulic speed reducer or a pump wheel and a turbine of a hydraulic coupler; d is the effective working cycle circle diameter, and lambda is the torque coefficient, and can be obtained through the oil stirring power loss of each component in the comprehensive transmission system at different rotating speeds, wherein the expression of lambda is as follows:
in the formula, n_{B}The pump wheel speed of the fluid coupling or the fixed wheel speed of the fluid retarder, n_{T}The rotational speed of a turbine of the hydraulic coupler or the rotational speed of a driving wheel of the hydraulic retarder; if n is_{B}≠0,If n is_{B}0, λ is constant;
let δ be ρ_{0}'gλD^{5}Then, equation (8) is changed to:
P_{2}＝δn^{3}formula (10)
According to the formula (10), the oil churning power loss of the hydraulic element in the oilfilled state is related to the relative rotating speed between the impellers, namely the oil churning power loss of the hydraulic speed reducer is related to the relative rotating speed between the movable wheel and the fixed wheel, and the oil churning power loss of the hydraulic coupler is related to the relative rotating speed between the pump wheel and the turbine wheel; the less oil leakage of the liquid filling control valve, the smaller the relative rotating speed between the impellers, and the smaller the oil stirring power loss.
5. The design method for inhibiting the oil churning power loss of the transmission system according to claim 1, wherein the relation between the friction coefficient of the sealing ring material and the oil churning power loss in the step 2 is calculated as follows:
firstly, analyzing motion law influence factors, namely calculating the oil stirring power loss between two binding surfaces with relative motion in a relative highspeed motion space according to a motion state;
be equipped with rotary seal structure in the comprehensive transmission system, rotary seal structure includes: the rotary shaft, the oil distribution sleeve and the sealing ring; an annular groove is processed on the outer circumferential surface of the rotating shaft; the sealing ring is arranged in the annular groove; the oil distribution sleeve is sleeved outside the rotating shaft, and a gap is reserved between the inner circumferential surface of the oil distribution sleeve and the outer circumferential surface of the rotating shaft; the outer circumferential surface of the sealing ring is an AB surface, the inner circumferential surface of the sealing ring is a CD surface, and the two end surfaces of the sealing ring are respectively an AD surface and a CB surface; wherein, the AB surface of the sealing ring is in contact with the inner circumferential surface of the oil distribution sleeve; the BC surface of the sealing ring is in fit contact with the wall surface of the annular groove on the rotating shaft; the sealing oil of the comprehensive transmission system is filled in the annular groove on the rotating shaft, and the oil pressure of the sealing oil is p_{0}Under the action of the pressure of the sealing oil, frictional resistance F is generated between the AB surface of the sealing ring and the inner circumferential surface of the oil distribution sleeve_{AB}CB surface of seal ring and rotary shaftGenerates frictional resistance F between the wall surfaces of the annular groove_{CB}；
When F is present_{CB}>F_{AB}When the oil stirring device is used, the sealing ring and the rotating shaft rotate together, and the oil stirring power loss comes from frictional resistance F_{AB}；
F_{AB}＝p_{0}2πr_{1}Hf_{1}Formula (11)
In the formula, r_{1}Is the outer diameter of the seal ring, H is the axial length of the seal ring, f_{1}The friction coefficient between the sealing ring and the oil distribution sleeve is defined as the friction coefficient;
when F is present_{CB}<F_{AB}When the oil mixing machine is used, the sealing ring and the oil distribution sleeve rotate together, and the oil mixing power loss comes from frictional resistance F_{CB}；
In the formula, r_{1}Is the outer diameter of the sealing ring, r_{2}The inner diameter of the seal ring is delta is the clearance between the outer circumferential surface of the rotating shaft and the inner circumferential surface of the oil distribution sleeve, f_{2}The coefficient of friction between the sealing ring and the wall surface of the annular groove of the rotating shaft;
when F is present_{CB}＝F_{AB}When the sealing ring rotates along with the rotating shaft, the oil stirring power loss comes from frictional resistance F_{AB}(ii) a When the sealing ring rotates along with the oil distribution sleeve, the oil stirring power loss comes from frictional resistance F_{CB}；
Judging the motion state of the seal ring according to the motion coefficient sigma, wherein the motion coefficient sigma is expressed as follows:
according to the formula (13), since the machining accuracy of the rotary shaft and the oil distribution sleeve is the same, the friction coefficient f_{1}＝f_{2}The motion coefficient sigma is only related to the geometric dimension and fit clearance of the sealing ring, and the sealing ring is sealedThe geometric dimension and fit clearance of the seal ring are substituted into the formula (13), sigma is calculated, and the calculation result shows that sigma is far less than 1, so that the seal ring and the oil distribution sleeve rotate together, and the power loss of the seal ring comes from frictional resistance F_{CB}；
Secondly, the friction resistance influencing factor analysis is carried out, namely, the friction coefficient f in the formula (12) is determined through experiments_{2}；
The formula (12) deduces the expression of the friction torque M applied to the sealing ring as follows:
wherein D is frictional resistance F_{CB}The value of the friction torque M can be obtained by tests, which are: selecting more than two sealing ring samples with the same geometric dimension but different materials, performing a contrast test, and obtaining the friction torque M borne by the sealing ring through a torquemeter test in the test process;
the friction coefficient f can be obtained by substituting the test result, i.e., the value of the friction torque M, into the formula (14)_{2}The change rule of the friction coefficient change and the friction torque of the sealing rings made of different materials is obtained according to the change trend as follows:
thirdly, calculating the oil stirring power loss P of the sealing ring according to the formula (15)_{3}The expression is as follows:
in the formula, n is the rotating speed of the rotating shaft;
according to the formula (16), the oil churning power loss of the sealing ring is related to the friction coefficient of the material, and the smaller the friction coefficient of the material of the sealing ring is, the smaller the oil churning power loss is.
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