CN104773151A - Method and device for automatically acquiring liquid filling ratio of hydrodynamic retarder - Google Patents

Abstract

The invention discloses a method and a device for automatically acquiring liquid filling ratio of a hydrodynamic retarder. The method comprises the following steps of establishing a driving force-running resistance equation; judging the working state of the hydrodynamic retarder; if the hydrodynamic retarder is in a control state at the initial stage of deceleration, acquiring the liquid filling ratio according to the equation and the maximum heat sink power; if the hydrodynamic retarder is in a control state at the later stage of deceleration, acquiring the liquid filling ratio according to the equation and the maximum braking power; if the hydrodynamic retarder is in a control state at the constant speed stage, acquiring the liquid filling ratio according to the equation, current liquid filling ratio and a value of slope. According to the method disclosed by the embodiment of the invention, under different working conditions of the hydrodynamic retarder, the liquid filling ratio in which the hydrodynamic retarder needs to be positioned currently is automatically output by extracting parameters of a complete vehicle, so automatic control and rapid liquid filling ratio positioning are realized, the stability of vehicle running is guaranteed, and the service life of a valve body is prolonged; the method is simple and convenient.

Description

Automatic liquid filling ratio obtaining method and device for hydraulic retarder

Technical Field

The invention relates to the technical field of vehicles, in particular to a method and a device for automatically acquiring a liquid filling ratio of a hydraulic retarder.

Background

When the vehicle runs on a slope, the hydraulic retarder replaces service braking, and therefore the purpose that the vehicle is decelerated to a constant speed is achieved automatically. Specifically, the hydrodynamic retarder converts kinetic energy of the vehicle into internal energy of the working fluid of the hydrodynamic retarder, and the internal energy is dissipated by a vehicle radiator. The torque of the hydraulic retarder is related to the current rotating speed and the proportion of gas and liquid in the working cavity, and is limited by the current heat dissipation power of the vehicle.

The working condition of the hydrodynamic retarder is divided into the following three stages: A. and controlling in the early deceleration stage. In the process, the rotating speed of the retarder is high, large torque is easily generated, the braking power is easily larger than the heat dissipation power of the vehicle, the temperature of the working fluid rises, and the working fluid is permanently damaged once the temperature of the working fluid exceeds the allowable temperature. B. And controlling the late deceleration. In the process, the rotating speed of the retarder is reduced, and the retarder needs to be in a full liquid filling working state all the time so as to ensure the braking efficiency of the retarder. C. And (5) controlling a constant speed stage. In the process, the vehicle can run at a constant speed immediately at any achievable speed, so that the retarder is required to automatically adjust the liquid filling ratio and output the braking torque at the constant speed.

The technical problem to be solved is as follows: 1. automatic braking control based on maximum heat dissipation power; 2. automatic braking control based on maximum braking power; 3. automatic constant speed control based on a complex road surface. Three technical problems are all related to dynamically and automatically adjusting the liquid filling ratio in the working cavity of the retarder under the condition of variable rotating speed. Therefore, key points for solving the technical problem include: 1. automatic control; 2. and positioning the quick liquid filling ratio.

In the related art, for the key point 1: in the related technology, for example, in a hierarchical control strategy, the liquid filling ratio of the hydraulic retarder is divided into four gears which are respectively 100%, 75%, 50% and 25%, different liquid filling ratios correspond to different output torques, and a driver automatically selects which gear the retarder works in according to the driving condition. For keypoint 2: in the related art, for example, the control strategy is continuously iterative. For example, the driver gives a target constant speed u₁At the current vehicle speed u₂Greater than u₁When the speed reducer is automatically increased by 10 percent of liquid filling rate per time step, and the speed reducer is at the current speed u₂Less than u₁The retarder is automatically reduced by a filling rate of 10% per time step. And continuous iterative constant speed control is performed.

However, for the above-described key point 1: the output torque can be adjusted only manually, and cannot be adjusted automatically. For the above key point 2: according to different responses of the selected valve body of the vehicle, the time step length and the liquid filling rate changed in each step length are different, but the current vehicle speed u is generated₂At the target vehicle speed u₁The phenomenon of nearby fluctuation and the situation of continuous adjustment forever can not lock the corresponding liquid filling ratio, and the final constant speed time becomes very long due to the existence of iteration, and particularly when the automobile runs on a road with complex road conditions, the time for the vehicle to reach the constant speed becomes longer by the above strategy.

Disclosure of Invention

The present invention is directed to solving, at least to some extent, one of the technical problems in the related art described above.

Therefore, the invention aims to provide a simple and convenient automatic liquid filling ratio acquisition method for the hydraulic retarder, which can realize quick liquid filling ratio positioning.

The invention also aims to provide a liquid filling ratio automatic acquisition device of the hydraulic retarder.

In order to achieve the above object, an embodiment of the invention provides an automatic liquid filling ratio obtaining method for a hydraulic retarder, which includes the following steps: establishing a driving force-running resistance equation, wherein the driving force-running resistance equation includes: the driving force, the wind resistance, the rolling resistance and the output braking force of the hydraulic retarder; judging the working state of the hydraulic retarder, wherein the working state comprises a deceleration initial control state, a deceleration later control state and a constant speed stage control state; if the control state is the initial deceleration control state, obtaining a first liquid filling ratio of the hydraulic retarder according to the driving force-running resistance equation and the maximum heat dissipation power of the hydraulic retarder; if the control state is the later deceleration control state, obtaining a second liquid filling ratio of the hydraulic retarder according to the driving force-running resistance equation and the maximum braking power of the hydraulic retarder; and if the control state is the constant speed stage control state, obtaining a third liquid filling ratio of the hydraulic retarder according to the driving force-running resistance equation and the current liquid filling ratio and gradient value of the hydraulic retarder.

According to the method for automatically acquiring the liquid filling ratio of the hydraulic retarder provided by the embodiment of the invention, under different working conditions of the hydraulic retarder, the liquid filling ratio at which the hydraulic retarder is currently located is automatically output by extracting the parameters of the whole vehicle, namely, the control target of the liquid filling ratio is acquired, and automatic control and quick positioning of the liquid filling ratio are realized, so that the vehicle is quickly stabilized, the running stability of the vehicle is ensured, the service life of a valve body is prolonged, and the method is simple and convenient.

In addition, the automatic liquid filling ratio obtaining method for the hydraulic retarder according to the above embodiment of the present invention may further have the following additional technical features:

further, in one embodiment of the present invention, the formula of the driving force-running resistance equation is:

$m{\stackrel{.}{u}}_a=G_x-F_f-F_w-F_r,$

wherein G is_xIs the driving force, F_wTo the wind resistance, F_fFor said rolling resistance, F_rAnd outputting the braking force for the hydraulic retarder.

Further, in an embodiment of the present invention, the first liquid filling ratio of the hydraulic retarder is:

<math> <mrow> <msup> <msub> <mi>&gamma;</mi> <mn>1</mn> </msub> <mo>^</mo> </msup> <mo>=</mo> <mfrac> <mrow> <msub> <mi>W</mi> <mi>radiating</mi> </msub> <mo>&CenterDot;</mo> <mn>9549</mn> </mrow> <mrow> <msub> <mi>a</mi> <mn>1</mn> </msub> <mo>&CenterDot;</mo> <msub> <mi>u</mi> <mi>a</mi> </msub> <mo>&CenterDot;</mo> <mi>T</mi> </mrow> </mfrac> <mo>,</mo> </mrow> </math>

wherein, W_radiatingIs the maximum heat dissipation power, a₁As a conversion factor, u_aAnd T is the running speed of the vehicle, and T is the output torque of the hydraulic retarder.

Further, in an embodiment of the invention, the second liquid filling ratio γ of the hydrodynamic retarder₂ ^{^}≡1。

Further, in an embodiment of the present invention, the third liquid filling ratio of the hydraulic retarder is:

<math> <mrow> <msup> <msub> <mi>&gamma;</mi> <mn>3</mn> </msub> <mo>^</mo> </msup> <mo>=</mo> <mi>&gamma;</mi> <mo>+</mo> <mfrac> <mrow> <mo>-</mo> <mfrac> <mrow> <mi>F</mi> <mrow> <mo>(</mo> <msub> <mi>u</mi> <mrow> <mi>a</mi> <mn>1</mn> </mrow> </msub> <mo>)</mo> </mrow> <mo>+</mo> <mi>F</mi> <mrow> <mo>(</mo> <msub> <mi>u</mi> <mrow> <mi>a</mi> <mn>2</mn> </mrow> </msub> <mo>)</mo> </mrow> </mrow> <mrow> <msub> <mover> <mi>u</mi> <mo>.</mo> </mover> <mrow> <mi>a</mi> <mn>1</mn> </mrow> </msub> <mo>+</mo> <msub> <mover> <mi>u</mi> <mo>.</mo> </mover> <mrow> <mi>a</mi> <mn>2</mn> </mrow> </msub> </mrow> </mfrac> <msub> <mover> <mi>u</mi> <mo>.</mo> </mover> <mi>a</mi> </msub> </mrow> <mrow> <msub> <mi>l</mi> <mn>2</mn> </msub> <mo>&CenterDot;</mo> <msup> <msub> <mi>u</mi> <mi>a</mi> </msub> <mn>2</mn> </msup> </mrow> </mfrac> <mo>,</mo> </mrow> </math>

gamma is the current fill ratio, u_a1Is a first vehicle speed u_a2In order to set the second vehicle speed to the second vehicle speed,is a first acceleration corresponding to the vehicle at the first vehicle speed,is a second acceleration corresponding to the vehicle at the second vehicle speed,as the current acceleration of the vehicle, /)₂At a predetermined value, u_aIs the target constant speed vehicle speed of the vehicle.

In another aspect, an embodiment of the present invention provides an automatic liquid filling ratio obtaining apparatus for a hydraulic retarder, including: an establishment module for establishing a driving force-running resistance equation, wherein the driving force-running resistance equation includes: the driving force, the wind resistance, the rolling resistance and the output braking force of the hydraulic retarder; the judging module is used for judging the working state of the hydraulic retarder, wherein the working state comprises a deceleration initial control state, a deceleration later control state and a constant speed stage control state; and the acquisition module is used for obtaining a first liquid filling ratio of the hydraulic retarder according to the driving force-driving resistance equation and the maximum heat dissipation power of the hydraulic retarder when the control state is in the initial deceleration control state, obtaining a second liquid filling ratio of the hydraulic retarder according to the driving force-driving resistance equation and the maximum braking power of the hydraulic retarder when the control state is in the late deceleration control state, and obtaining a third liquid filling ratio of the hydraulic retarder according to the driving force-driving resistance equation, the current liquid filling ratio of the hydraulic retarder and the gradient value when the control state is in the constant speed stage control state.

According to the automatic liquid filling ratio acquisition device for the hydraulic retarder provided by the embodiment of the invention, under different working conditions of the hydraulic retarder, the liquid filling ratio at which the hydraulic retarder is currently located is automatically output by extracting the parameters of the whole vehicle, namely, the control target of the liquid filling ratio is acquired, and automatic control and quick liquid filling ratio positioning are realized, so that the vehicle is quickly stabilized, the running stability of the vehicle is ensured, the service life of the valve body is prolonged, and the device is simple and convenient.

In addition, the automatic liquid filling ratio acquiring device for the hydraulic retarder according to the above embodiment of the present invention may further have the following additional technical features:

further, in one embodiment of the present invention, the formula of the driving force-running resistance equation is:

$m{\stackrel{.}{u}}_a=G_x-F_f-F_w-F_r,$

wherein G is_xIs the driving force, F_wTo the wind resistance, F_fFor said rolling resistance, F_rAnd outputting the braking force for the hydraulic retarder.

Further, in an embodiment of the present invention, the first liquid filling ratio of the hydraulic retarder is:

<math> <mrow> <msup> <msub> <mi>&gamma;</mi> <mn>1</mn> </msub> <mo>^</mo> </msup> <mo>=</mo> <mfrac> <mrow> <msub> <mi>W</mi> <mi>radiating</mi> </msub> <mo>&CenterDot;</mo> <mn>9549</mn> </mrow> <mrow> <msub> <mi>a</mi> <mn>1</mn> </msub> <mo>&CenterDot;</mo> <msub> <mi>u</mi> <mi>a</mi> </msub> <mo>&CenterDot;</mo> <mi>T</mi> </mrow> </mfrac> <mo>,</mo> </mrow> </math>

wherein, W_radiatingIs the maximum heat dissipation power, a₁As a conversion factor, u_aAnd T is the running speed of the vehicle, and T is the output torque of the hydraulic retarder.

Further, in an embodiment of the invention, the second liquid filling ratio γ of the hydrodynamic retarder₂ ^{^}≡1。

Further, in an embodiment of the present invention, the third liquid filling ratio of the hydraulic retarder is:

<math> <mrow> <msup> <msub> <mi>&gamma;</mi> <mn>3</mn> </msub> <mo>^</mo> </msup> <mo>=</mo> <mi>&gamma;</mi> <mo>+</mo> <mfrac> <mrow> <mo>-</mo> <mfrac> <mrow> <mi>F</mi> <mrow> <mo>(</mo> <msub> <mi>u</mi> <mrow> <mi>a</mi> <mn>1</mn> </mrow> </msub> <mo>)</mo> </mrow> <mo>+</mo> <mi>F</mi> <mrow> <mo>(</mo> <msub> <mi>u</mi> <mrow> <mi>a</mi> <mn>2</mn> </mrow> </msub> <mo>)</mo> </mrow> </mrow> <mrow> <msub> <mover> <mi>u</mi> <mo>.</mo> </mover> <mrow> <mi>a</mi> <mn>1</mn> </mrow> </msub> <mo>+</mo> <msub> <mover> <mi>u</mi> <mo>.</mo> </mover> <mrow> <mi>a</mi> <mn>2</mn> </mrow> </msub> </mrow> </mfrac> <msub> <mover> <mi>u</mi> <mo>.</mo> </mover> <mi>a</mi> </msub> </mrow> <mrow> <msub> <mi>l</mi> <mn>2</mn> </msub> <mo>&CenterDot;</mo> <msup> <msub> <mi>u</mi> <mi>a</mi> </msub> <mn>2</mn> </msup> </mrow> </mfrac> <mo>,</mo> </mrow> </math>

gamma is the current fill ratio, u_a1Is a first vehicle speed u_a2In order to set the second vehicle speed to the second vehicle speed,is a first acceleration corresponding to the vehicle at the first vehicle speed,is a second acceleration corresponding to the vehicle at the second vehicle speed,as the current acceleration of the vehicle, /)₂At a predetermined value, u_aIs the target constant speed vehicle speed of the vehicle.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

fig. 1 is a flowchart of a method for automatically obtaining a charging ratio of a hydrodynamic retarder according to an embodiment of the present invention;

FIG. 2 is a schematic view of a vehicle traveling according to one embodiment of the present invention;

FIG. 3 is a schematic process diagram of a hydrodynamic retarder braking for a vehicle according to an embodiment of the present invention;

FIG. 4 is a schematic of observer-free vehicle speed versus time, in accordance with one embodiment of the present invention;

FIG. 5 is a schematic of the fill rate of a working chamber without a viewer according to one embodiment of the present invention;

FIG. 6 is a schematic diagram of vehicle speed versus time with an observer, according to one embodiment of the present invention;

FIG. 7 is a schematic view of the fill rate of a working chamber with an observer according to one embodiment of the present invention;

FIG. 8 is a graphical illustration of velocity versus time in a mass observation error, in accordance with one embodiment of the present invention;

FIG. 9 is a diagram illustrating corresponding fill rates in mass observation errors, in accordance with one embodiment of the present invention; and

fig. 10 is a schematic structural diagram of an automatic liquid filling ratio acquiring device of a hydrodynamic retarder according to an embodiment of the present invention.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.

In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally connected; 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 by those skilled in the art according to specific situations.

In the present invention, unless otherwise expressly stated or limited, "above" or "below" a first feature means that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact with each other via another feature therebetween. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly above and obliquely above the second feature, or simply meaning that the first feature is at a lesser level than the second feature.

The method and the device for automatically acquiring the liquid filling ratio of the hydraulic retarder according to the embodiment of the invention are described below with reference to the accompanying drawings, and first, the method for automatically acquiring the liquid filling ratio of the hydraulic retarder according to the embodiment of the invention will be described with reference to the accompanying drawings. Referring to fig. 1, the method includes the steps of:

s101, establishing a driving force-driving resistance equation, wherein the driving force-driving resistance equation comprises the following steps: driving force, wind resistance, rolling resistance and output braking force of the hydraulic retarder.

In one embodiment of the present invention, referring to fig. 2, the formula of the driving force-running resistance equation is:

$m{\stackrel{.}{u}}_a=G_x-F_f-F_w-F_r,$

wherein G is_xAs a driving force, F_wFor wind resistance, F_fTo rolling resistance, F_rFor the output of the braking force of the hydrodynamic retarder, different braking phases, F_rThe specific representation rows are different.

And S102, judging the working state of the hydraulic retarder, wherein the working state comprises a deceleration initial control state, a deceleration later control state and a constant speed stage control state.

Further, referring to fig. 3, the whole process of the braking phase of the hydrodynamic retarder for vehicle is divided into three sections: stage1, stage2, and stage 3. Of these, stage1 (the most importantHigh heat dissipation power control) corresponds to the initial deceleration control state:stage2 (maximum brake power control) corresponds to the late deceleration control state:stage3 (constant speed control) corresponds to the constant speed stage control state:in addition, F_r1、F_r2And F_r3The output braking force of the hydraulic retarder at the stage of stage1, stage2 and stage3 respectively.

Specifically, stage 1: the rotor speed is too high, and the maximum braking power that can produce of hydraulic retarber this moment is greater than the heat dissipation power, so this stage adopts the control strategy based on maximum heat dissipation power: f_r1＝f₁(u_a,W_r). stage 2: the rotating speed of the rotor is reduced, and the maximum braking power which can be generated by the hydraulic retarder is smaller than the heat dissipation power, so that a control strategy based on the maximum braking power is adopted at the stage: f_r2＝f₂(u_a). stage 3: when the vehicle reaches the target speed, the hydraulic retarder adopts a constant speed control strategy, and the hydraulic retarder rotor can be driven to rotate at the same speed by adjusting the liquid filling ratio,

the braking torques with different sizes are output, and finally the purpose that the vehicle runs on a slope at a constant speed is achieved: f_r3＝f₃(u_a,γ)。

S103, if the control state is the initial deceleration control state, obtaining a first liquid filling ratio of the hydraulic retarder according to a driving force-running resistance equation and the maximum heat dissipation power of the hydraulic retarder.

In one embodiment of the invention, the first charge-liquid ratio of the hydrodynamic retarder is:

<math> <mrow> <msup> <msub> <mi>&gamma;</mi> <mn>1</mn> </msub> <mo>^</mo> </msup> <mo>=</mo> <mfrac> <mrow> <msub> <mi>W</mi> <mi>radiating</mi> </msub> <mo>&CenterDot;</mo> <mn>9549</mn> </mrow> <mrow> <msub> <mi>a</mi> <mn>1</mn> </msub> <mo>&CenterDot;</mo> <msub> <mi>u</mi> <mi>a</mi> </msub> <mo>&CenterDot;</mo> <mi>T</mi> </mrow> </mfrac> <mo>,</mo> </mrow> </math>

wherein, W_radiatingTo maximize the heat dissipation power, a₁As a conversion factor, u_aAnd T is the output torque of the hydraulic retarder.

And S104, if the control state is the control state in the later deceleration stage, obtaining a second liquid filling ratio of the hydraulic retarder according to the driving force-running resistance equation and the maximum braking power of the hydraulic retarder.

In one embodiment of the invention, the second charge ratio γ of the hydrodynamic retarder₂ ^{^}≡1。

And S105, if the control state is the constant speed stage control state, obtaining a third liquid filling ratio of the hydraulic retarder according to the driving force-running resistance equation and the current liquid filling ratio and gradient value of the hydraulic retarder.

In an embodiment of the invention, the third charge-liquid ratio of the hydrodynamic retarder is:

<math> <mrow> <msup> <msub> <mi>&gamma;</mi> <mn>3</mn> </msub> <mo>^</mo> </msup> <mo>=</mo> <mi>&gamma;</mi> <mo>+</mo> <mfrac> <mrow> <mo>-</mo> <mfrac> <mrow> <mi>F</mi> <mrow> <mo>(</mo> <msub> <mi>u</mi> <mrow> <mi>a</mi> <mn>1</mn> </mrow> </msub> <mo>)</mo> </mrow> <mo>+</mo> <mi>F</mi> <mrow> <mo>(</mo> <msub> <mi>u</mi> <mrow> <mi>a</mi> <mn>2</mn> </mrow> </msub> <mo>)</mo> </mrow> </mrow> <mrow> <msub> <mover> <mi>u</mi> <mo>.</mo> </mover> <mrow> <mi>a</mi> <mn>1</mn> </mrow> </msub> <mo>+</mo> <msub> <mover> <mi>u</mi> <mo>.</mo> </mover> <mrow> <mi>a</mi> <mn>2</mn> </mrow> </msub> </mrow> </mfrac> <msub> <mover> <mi>u</mi> <mo>.</mo> </mover> <mi>a</mi> </msub> </mrow> <mrow> <msub> <mi>l</mi> <mn>2</mn> </msub> <mo>&CenterDot;</mo> <msup> <msub> <mi>u</mi> <mi>a</mi> </msub> <mn>2</mn> </msup> </mrow> </mfrac> <mo>,</mo> </mrow> </math>

gamma is the current fill ratio, u_a1Is a first vehicle speed u_a2In order to set the second vehicle speed to the second vehicle speed,is a first acceleration corresponding to the vehicle at a first vehicle speed,a second acceleration corresponding to the vehicle at a second vehicle speed,as the current acceleration of the vehicle, /)₂At a predetermined value, u_aIs the target constant speed vehicle speed of the vehicle. The preset value can be a constant and can be set according to actual conditions.

It should be noted that the embodiment of the present invention can be implemented by an observer built in the vehicle, so that the automatic control and the fast liquid filling ratio positioning can be realized by designing the observer, and the present invention is further explained by a specific embodiment of the observer design.

Referring to fig. 2, the driving force travel-running resistance equation:

$m{\stackrel{.}{u}}_a=G_x-F_f-F_w-F_r,$

wherein,

F_f＝mg·f

f＝7.6×10^-3+5.6×10^-5u_a，

<math> <mrow> <msub> <mi>F</mi> <mi>w</mi> </msub> <mo>=</mo> <mfrac> <mrow> <msub> <mi>C</mi> <mi>D</mi> </msub> <mo>&CenterDot;</mo> <mi>A</mi> <mo>&CenterDot;</mo> <msubsup> <mi>u</mi> <mi>a</mi> <mn>2</mn> </msubsup> </mrow> <mn>21.15</mn> </mfrac> <mo>,</mo> </mrow> </math>

F_wis wind resistance; c_DIs the air resistance coefficient; a is the windward area; u. of_aThe vehicle running speed. In the figure, G is the vehicle weight; theta is the gradient; f_fIs the rolling resistance.

Namely, observer design of the liquid filling ratio:

stage 1-maximum dissipated power braking,

<math> <mrow> <msub> <mi>W</mi> <mi>r</mi> </msub> <mo>=</mo> <mfrac> <mrow> <mi>&gamma;</mi> <mo>&CenterDot;</mo> <msub> <mi>T</mi> <mi>r</mi> </msub> <mo>&CenterDot;</mo> <mi>n</mi> </mrow> <mn>9549</mn> </mfrac> </mrow> </math>

F_r1·R＝i₁·i₂·γ·T_r

n＝a₁·u_a，

to obtain

<math> <mrow> <msub> <mi>F</mi> <mrow> <mi>r</mi> <mn>1</mn> </mrow> </msub> <mo>=</mo> <mfrac> <mrow> <mn>9549</mn> <mo>&CenterDot;</mo> <msub> <mi>W</mi> <mi>r</mi> </msub> <mo>&CenterDot;</mo> <msub> <mi>i</mi> <mn>1</mn> </msub> <mo>&CenterDot;</mo> <msub> <mi>i</mi> <mn>2</mn> </msub> </mrow> <mrow> <msub> <mi>a</mi> <mn>1</mn> </msub> <mo>&CenterDot;</mo> <mi>R</mi> <mo>&CenterDot;</mo> <msub> <mi>u</mi> <mi>a</mi> </msub> </mrow> </mfrac> <mo>=</mo> <mfrac> <msub> <mi>l</mi> <mn>1</mn> </msub> <msub> <mi>u</mi> <mi>a</mi> </msub> </mfrac> </mrow> </math>

<math> <mrow> <mi>&gamma;</mi> <mo>=</mo> <mfrac> <mrow> <mn>9549</mn> <msub> <mi>W</mi> <mi>r</mi> </msub> </mrow> <mrow> <msub> <mi>a</mi> <mn>1</mn> </msub> <mo>&CenterDot;</mo> <msub> <mi>T</mi> <mi>r</mi> </msub> <mo>&CenterDot;</mo> <msub> <mi>u</mi> <mi>a</mi> </msub> </mrow> </mfrac> <mo>,</mo> </mrow> </math>

Wherein,

<math> <mrow> <msub> <mi>l</mi> <mn>1</mn> </msub> <mo>=</mo> <mfrac> <mrow> <mn>9549</mn> <mo>&CenterDot;</mo> <msub> <mi>W</mi> <mi>r</mi> </msub> <mo>&CenterDot;</mo> <msub> <mi>i</mi> <mn>1</mn> </msub> <mo>&CenterDot;</mo> <msub> <mi>i</mi> <mn>2</mn> </msub> </mrow> <mrow> <mi>R</mi> <mo>&CenterDot;</mo> <msub> <mi>a</mi> <mn>1</mn> </msub> </mrow> </mfrac> <mo>,</mo> </mrow> </math>

wherein gamma is the current liquid filling ratio, namely the original liquid filling ratio; n is the rotation speed; a is₁Is a conversion factor; r is the radius of the wheel; t is_rOutput torque at full charge; w_rThe method is determined according to different vehicles and different working conditions, and can be temporarily set as a fixed value; i.e. i₁、i₂The speed ratios of the gearbox and the main reducer are respectively.

Then during stage1, the driving force-running resistance equation takes the specific form:

<math> <mrow> <mi>m</mi> <msub> <mover> <mi>u</mi> <mo>.</mo> </mover> <mi>a</mi> </msub> <mo>=</mo> <mi>mg</mi> <mi>sin</mi> <mi>&theta;</mi> <mo>-</mo> <mrow> <mo>(</mo> <mi>c</mi> <mo>+</mo> <msub> <mi>ku</mi> <mi>a</mi> </msub> <mo>)</mo> </mrow> <mo>-</mo> <msubsup> <mi>bu</mi> <mi>a</mi> <mn>2</mn> </msubsup> <mo>-</mo> <mfrac> <msub> <mi>l</mi> <mn>1</mn> </msub> <msub> <mi>u</mi> <mi>a</mi> </msub> </mfrac> <mo>.</mo> </mrow> </math>

further, stage2 — maximum brake power braking:

F_r2·R＝i₁·i₂·γ·T_r，

in this process, γ ≡ 1 is used because the liquid is filled in the full range.

T_r＝λ·ρ·n²·D⁵＝a₂n²，

In the formula, rho is fluid density, and the working solution can be a mixed solution of water and glycol; lambda is performance factor; n is rotor speed; d is a profile diameter.

<math> <mrow> <msub> <mi>F</mi> <mrow> <mi>r</mi> <mn>2</mn> </mrow> </msub> <mo>=</mo> <mfrac> <mrow> <msubsup> <mi>a</mi> <mn>1</mn> <mn>2</mn> </msubsup> <mo>&CenterDot;</mo> <msub> <mi>a</mi> <mn>2</mn> </msub> <mo>&CenterDot;</mo> <msub> <mi>i</mi> <mn>1</mn> </msub> <mo>&CenterDot;</mo> <msub> <mi>i</mi> <mn>2</mn> </msub> </mrow> <mi>R</mi> </mfrac> <mo>&CenterDot;</mo> <msubsup> <mi>u</mi> <mi>a</mi> <mn>2</mn> </msubsup> <mo>=</mo> <msub> <mi>l</mi> <mn>2</mn> </msub> <msubsup> <mi>u</mi> <mi>a</mi> <mn>2</mn> </msubsup> <mo>.</mo> </mrow> </math>

Wherein,

<math> <mrow> <msub> <mi>l</mi> <mn>2</mn> </msub> <mo>=</mo> <mfrac> <mrow> <msubsup> <mi>a</mi> <mn>1</mn> <mn>2</mn> </msubsup> <mo>&CenterDot;</mo> <msub> <mi>a</mi> <mn>2</mn> </msub> <mo>&CenterDot;</mo> <msub> <mi>i</mi> <mn>1</mn> </msub> <mo>&CenterDot;</mo> <msub> <mi>i</mi> <mn>2</mn> </msub> </mrow> <mi>R</mi> </mfrac> <mo>.</mo> </mrow> </math>

during stage2, the driving force-running resistance equation takes the specific form:

<math> <mrow> <mi>m</mi> <msub> <mover> <mi>u</mi> <mo>.</mo> </mover> <mi>a</mi> </msub> <mo>=</mo> <mi>mg</mi> <mi>sin</mi> <mi>&theta;</mi> <mo>-</mo> <mrow> <mo>(</mo> <mi>c</mi> <mo>+</mo> <msub> <mi>ku</mi> <mi>a</mi> </msub> <mo>)</mo> </mrow> <mo>-</mo> <msubsup> <mi>bu</mi> <mi>a</mi> <mn>2</mn> </msubsup> <mo>-</mo> <msub> <mi>l</mi> <mn>2</mn> </msub> <msubsup> <mi>u</mi> <mi>a</mi> <mn>2</mn> </msubsup> <mo>.</mo> </mrow> </math>

further, stage 3-constant speed brake control. Wherein, stage3 is divided into two cases for analysis:

start constant speed control at any point of a.stage2, and proceed to stage 3. And respectively establishing a full liquid-filled deceleration system equation and a target partial liquid-filled constant speed system equation before and after the time t of stage 3.

<math> <mrow> <mi>m</mi> <msub> <mover> <mi>u</mi> <mo>.</mo> </mover> <mi>a</mi> </msub> <mo>=</mo> <mi>mg</mi> <mi>sin</mi> <mi>&theta;</mi> <mo>-</mo> <msub> <mi>F</mi> <mi>f</mi> </msub> <mo>-</mo> <msub> <mi>F</mi> <mi>w</mi> </msub> <mo>-</mo> <msub> <mi>F</mi> <mrow> <mi>r</mi> <mn>2</mn> </mrow> </msub> <mo>,</mo> </mrow> </math>

0＝mgsinθ-F_f-F_w-γ^{^}·F_r2，

Between two time points, if the time is short, the gradient is considered unchanged, and it can be:

<math> <mrow> <msup> <mi>&gamma;</mi> <mo>^</mo> </msup> <mo>=</mo> <mn>1</mn> <mo>+</mo> <mfrac> <mrow> <mi>m</mi> <msub> <mover> <mi>u</mi> <mo>.</mo> </mover> <mi>a</mi> </msub> </mrow> <mrow> <msub> <mi>l</mi> <mn>2</mn> </msub> <mo>&CenterDot;</mo> <msubsup> <mi>u</mi> <mi>a</mi> <mn>2</mn> </msubsup> </mrow> </mfrac> <mo>.</mo> </mrow> </math>

B. the vehicle is already at constant speed at stage3, but the slope of the road has changed. Changing the original constant speed theta into a new constant speed theta' at the moment t, and then the kinetic equation before and after the gradient change moment t is as follows:

<math> <mrow> <mi>m</mi> <msub> <mover> <mi>u</mi> <mo>.</mo> </mover> <mi>a</mi> </msub> <mo>=</mo> <mi>mg</mi> <mi>sin</mi> <msup> <mi>&theta;</mi> <mo>&prime;</mo> </msup> <mo>-</mo> <msub> <mi>F</mi> <mi>f</mi> </msub> <mo>-</mo> <msub> <mi>F</mi> <mi>w</mi> </msub> <mo>-</mo> <msub> <mi>F</mi> <mrow> <mi>r</mi> <mn>2</mn> </mrow> </msub> <mo>&CenterDot;</mo> <mi>&gamma;</mi> <mo>,</mo> </mrow> </math>

0＝mgsinθ′-F_f-F_w-F_r2·γ′，

wherein gamma is the original liquid filling ratio; γ' is the charge ratio required to maintain constant velocity on the new grade, resulting in:

<math> <mrow> <msup> <mi>&gamma;</mi> <mo>^</mo> </msup> <mo>=</mo> <mi>&gamma;</mi> <mo>+</mo> <mfrac> <mrow> <mi>m</mi> <msub> <mover> <mi>u</mi> <mo>.</mo> </mover> <mi>a</mi> </msub> </mrow> <mrow> <msub> <mi>l</mi> <mn>2</mn> </msub> <mo>&CenterDot;</mo> <msubsup> <mi>u</mi> <mi>a</mi> <mn>2</mn> </msubsup> </mrow> </mfrac> <mo>.</mo> </mrow> </math>

the two cases of A and B can be expressed by the same formula:

<math> <mrow> <msup> <mi>&gamma;</mi> <mo>^</mo> </msup> <mo>=</mo> <mi>&gamma;</mi> <mo>+</mo> <mfrac> <mrow> <mi>m</mi> <msub> <mover> <mi>u</mi> <mo>.</mo> </mover> <mi>a</mi> </msub> </mrow> <mrow> <msub> <mi>l</mi> <mn>2</mn> </msub> <mo>&CenterDot;</mo> <msubsup> <mi>u</mi> <mi>a</mi> <mn>2</mn> </msubsup> </mrow> </mfrac> <mo>.</mo> </mrow> </math>

wherein,is the current vehicle speed acceleration; u. of_aA target constant speed vehicle speed; γ is at most 1.

During stage3, the driving force-running resistance equation takes the specific form:

<math> <mrow> <mi>m</mi> <msub> <mover> <mi>u</mi> <mo>.</mo> </mover> <mi>a</mi> </msub> <mo>=</mo> <mi>mg</mi> <mi>sin</mi> <mi>&theta;</mi> <mo>-</mo> <mrow> <mo>(</mo> <mi>c</mi> <mo>+</mo> <msub> <mi>ku</mi> <mi>a</mi> </msub> <mo>)</mo> </mrow> <mo>-</mo> <msubsup> <mi>bu</mi> <mi>a</mi> <mn>2</mn> </msubsup> <mo>-</mo> <msub> <mi>l</mi> <mn>2</mn> </msub> <msubsup> <mi>u</mi> <mi>a</mi> <mn>2</mn> </msubsup> <mo>&CenterDot;</mo> <msup> <mi>&gamma;</mi> <mo>^</mo> </msup> <mo>.</mo> </mrow> </math>

in summary, the target liquid filling ratio of the liquid filling ratio observer at stage1-stage3 is:

stage1: <math> <mrow> <msup> <mi>&gamma;</mi> <mo>^</mo> </msup> <mo>=</mo> <mfrac> <mrow> <msub> <mi>W</mi> <mi>radiating</mi> </msub> <mo>&CenterDot;</mo> <mn>9549</mn> </mrow> <mrow> <msub> <mi>a</mi> <mn>1</mn> </msub> <mo>&CenterDot;</mo> <msub> <mi>u</mi> <mi>a</mi> </msub> <mo>&CenterDot;</mo> <mi>T</mi> </mrow> </mfrac> <mo>,</mo> </mrow> </math> u is greater than u_a1；

stage2：γ^{^}≡1，u_a1U is less than u and greater than u_a2；

stage3: <math> <mrow> <msup> <mi>&gamma;</mi> <mo>^</mo> </msup> <mo>=</mo> <mi>&gamma;</mi> <mo>+</mo> <mfrac> <mrow> <mi>m</mi> <msub> <mover> <mi>u</mi> <mo>.</mo> </mover> <mi>a</mi> </msub> </mrow> <mrow> <msub> <mi>l</mi> <mn>2</mn> </msub> <mo>&CenterDot;</mo> <msubsup> <mi>u</mi> <mi>a</mi> <mn>2</mn> </msubsup> </mrow> </mfrac> <mo>,</mo> </mrow> </math> u_a2Less than u.

Further, the mass estimation equation can be derived from the kinetic equation:

$m{\stackrel{.}{u}}_a=G_x-F_f-F_w-F_r,$

wherein,

F(u_a)＝F_f+F_w+F_r，

the program of this embodiment may be set by default, and two time points t are taken after each time the hydrodynamic retarder is activated₁And t₂Respectively corresponding to the velocity u_a1And u_a2Two equations are established: (the time interval is small, and the gradient is not changed within the time interval by default).

$m{\stackrel{.}{u}}_{a1}=G_x-F\left(u_{a1}\right)$

$m{\stackrel{.}{u}}_{a2}=G_x-F\left(u_{a2}\right)$

Wherein,andthe value of (a) can be obtained from a sensor; f (u)_a1) And F (u)_a2) Can be obtained from the functional relationship. It can be found that:

$m=-\frac{F\left(u_{a1}\right)+F\left(u_{a2}\right)}{{\stackrel{.}{u}}_{a1}+{\stackrel{.}{u}}_{a2}}.$

in the continuous operation time of the single hydraulic retarder, two time points can be taken for a plurality of times in a short time to predict the mass m, so that the value m is accurately obtained, and the influence on the assumption that the gradient is unchanged in a time interval is eliminated.

And then, the derivation of the hydrodynamic retarder observer is finished:

stage1:(Current vehicle speed u) is greater than u_a1；

stage2：γ^{^}≡1，u_a1Less than (current vehicle speed u) and greater than u_a2；

stage3:u_a2Less than (current vehicle speed u).

In the embodiment of the invention, as shown in fig. 4 to 7, the vehicle system without the observer needs a long time to stabilize the vehicle speed, the hydrodynamic retarder with the observer can rapidly stabilize the vehicle speed, and the fluctuation phenomenon caused by continuous iteration of the vehicle speed and the liquid filling ratio does not occur, which is beneficial to the running stability of the vehicle and the service life of the valve body.

Further, in the embodiment of the invention, referring to fig. 8 and 9, even if the quality observation is in a problem, the constant speed control of the vehicle is still not affected, and the constant speed vehicle speed required by the driver can still be constant, the observer can automatically output different gas-liquid ratio control targets to make up for the error caused by the quality observation, and further adjust the speed of the whole vehicle.

According to the method for automatically acquiring the liquid filling ratio of the hydraulic retarder provided by the embodiment of the invention, under different working conditions of the hydraulic retarder, the liquid filling ratio at which the hydraulic retarder is currently located is automatically output by extracting the parameters of the whole vehicle, namely, the control target of the liquid filling ratio is acquired, and automatic control and quick positioning of the liquid filling ratio are realized, so that the vehicle is quickly stabilized, the running stability of the vehicle is ensured, the service life of a valve body is prolonged, and the method is simple and convenient.

The automatic liquid filling ratio acquisition device for the hydrodynamic retarder according to the embodiment of the invention is described below with reference to the accompanying drawings. Referring to fig. 10, the acquisition apparatus 100 includes: the device comprises a building module 10, a judging module 20 and an obtaining module 30.

The establishing module 10 is configured to establish a driving force-driving resistance equation, wherein the driving force-driving resistance equation includes: driving force, wind resistance, rolling resistance and output braking force of the hydraulic retarder. The determination module 20 is configured to determine an operating state of the hydraulic retarder, where the operating state includes a deceleration initial-stage control state, a deceleration later-stage control state, and a constant-speed-stage control state. The obtaining module 30 is configured to obtain a first liquid charging ratio of the hydraulic retarder according to a driving force-driving resistance equation and a maximum heat dissipation power of the hydraulic retarder when the control state is the initial deceleration control state, obtain a second liquid charging ratio of the hydraulic retarder according to the driving force-driving resistance equation and a maximum braking power of the hydraulic retarder when the control state is the late deceleration control state, and obtain a third liquid charging ratio of the hydraulic retarder according to the driving force-driving resistance equation and a current liquid charging ratio and a gradient value of the hydraulic retarder when the control state is the constant speed stage control state. According to the device provided by the embodiment of the invention, under different working conditions of the hydraulic retarder, the liquid filling ratio at which the hydraulic retarder is currently located is automatically output by extracting the parameters of the whole vehicle, so that automatic control and rapid positioning of the liquid filling ratio are realized, the running stability of the vehicle is ensured, the service life of the valve body is prolonged, and the device is simple and convenient.

In one embodiment of the present invention, referring to fig. 2, the formula of the driving force-running resistance equation is:

$m{\stackrel{.}{u}}_a=G_x-F_f-F_w-F_r,$

wherein G is_xAs a driving force, F_wFor wind resistance, F_fTo rolling resistance, F_rFor the output of the braking force of the hydrodynamic retarder, different braking phases, F_rThe specific representation rows are different.

Further, referring to fig. 3, the whole process of the braking phase of the hydrodynamic retarder for vehicle is divided into three sections: stage1, stage2, and stage 3. Wherein, stage1 (maximum heat dissipation power control) corresponds to the deceleration initial control state:stage2 (maximum brake power control) corresponds to the late deceleration control state:stage3 (constant speed control) corresponds to the constant speed stage control state:in addition, F_r1、F_r2And F_r3The output braking force of the hydraulic retarder at the stage of stage1, stage2 and stage3 respectively.

Specifically, stage 1: the rotor speed is too high, and the maximum braking power that can produce of hydraulic retarber this moment is greater than the heat dissipation power, so this stage adopts the control strategy based on maximum heat dissipation power: f_r1＝f₁(u_a,W_r). stage 2: the rotating speed of the rotor is reduced, and the maximum braking power which can be generated by the hydraulic retarder is smaller than the heat dissipation power, so that a control strategy based on the maximum braking power is adopted at the stage: f_r2＝f₂(u_a). stage 3: the vehicle reaches the target speed of a motor vehicle, and hydraulic retarber this moment adopts the constant speed control strategy, through adjusting the liquid filling ratio, can make hydraulic retarber rotor under the unchangeable condition of rotational speed, exports the braking torque of equidimension not, finally realizes the purpose that the vehicle goes at the ramp constant speed: f_r3＝f₃(u_a,γ)。

Further, in an embodiment of the present invention, the first liquid filling ratio of the hydrodynamic retarder is:

<math> <mrow> <msup> <msub> <mi>&gamma;</mi> <mn>1</mn> </msub> <mo>^</mo> </msup> <mo>=</mo> <mfrac> <mrow> <msub> <mi>W</mi> <mi>radiating</mi> </msub> <mo>&CenterDot;</mo> <mn>9549</mn> </mrow> <mrow> <msub> <mi>a</mi> <mn>1</mn> </msub> <mo>&CenterDot;</mo> <msub> <mi>u</mi> <mi>a</mi> </msub> <mo>&CenterDot;</mo> <mi>T</mi> </mrow> </mfrac> <mo>,</mo> </mrow> </math>

wherein, W_radiatingTo maximize the heat dissipation power, a₁As a conversion factor, u_aAnd T is the output torque of the hydraulic retarder.

Further, in an embodiment of the invention, the second liquid filling ratio γ of the hydrodynamic retarder₂ ^{^}≡1。

Further, in an embodiment of the present invention, the third liquid filling ratio of the hydraulic retarder is:

<math> <mrow> <msup> <msub> <mi>&gamma;</mi> <mn>3</mn> </msub> <mo>^</mo> </msup> <mo>=</mo> <mi>&gamma;</mi> <mo>+</mo> <mfrac> <mrow> <mo>-</mo> <mfrac> <mrow> <mi>F</mi> <mrow> <mo>(</mo> <msub> <mi>u</mi> <mrow> <mi>a</mi> <mn>1</mn> </mrow> </msub> <mo>)</mo> </mrow> <mo>+</mo> <mi>F</mi> <mrow> <mo>(</mo> <msub> <mi>u</mi> <mrow> <mi>a</mi> <mn>2</mn> </mrow> </msub> <mo>)</mo> </mrow> </mrow> <mrow> <msub> <mover> <mi>u</mi> <mo>.</mo> </mover> <mrow> <mi>a</mi> <mn>1</mn> </mrow> </msub> <mo>+</mo> <msub> <mover> <mi>u</mi> <mo>.</mo> </mover> <mrow> <mi>a</mi> <mn>2</mn> </mrow> </msub> </mrow> </mfrac> <msub> <mover> <mi>u</mi> <mo>.</mo> </mover> <mi>a</mi> </msub> </mrow> <mrow> <msub> <mi>l</mi> <mn>2</mn> </msub> <mo>&CenterDot;</mo> <msup> <msub> <mi>u</mi> <mi>a</mi> </msub> <mn>2</mn> </msup> </mrow> </mfrac> <mo>,</mo> </mrow> </math>

gamma is the current fill ratio, u_a1Is a first vehicle speed u_a2In order to set the second vehicle speed to the second vehicle speed,is a first acceleration corresponding to the vehicle at a first vehicle speed,a second acceleration corresponding to the vehicle at a second vehicle speed,is a vehicleFront acceleration,/₂At a predetermined value, u_aIs the target constant speed vehicle speed of the vehicle. The preset value can be a constant and can be set according to actual conditions.

It should be noted that the embodiment of the present invention can be implemented by an observer built in the vehicle, so that the automatic control and the fast liquid filling ratio positioning can be realized by designing the observer, and the present invention is further explained by a specific embodiment of the observer design.

Referring to fig. 2, the driving force travel-running resistance equation:

$m{\stackrel{.}{u}}_a=G_x-F_f-F_w-F_r,$

wherein,

F_f＝mg·f

f＝7.6×10^-3+5.6×10^-5u_a，

<math> <mrow> <msub> <mi>F</mi> <mi>w</mi> </msub> <mo>=</mo> <mfrac> <mrow> <msub> <mi>C</mi> <mi>D</mi> </msub> <mo>&CenterDot;</mo> <mi>A</mi> <mo>&CenterDot;</mo> <msubsup> <mi>u</mi> <mi>a</mi> <mn>2</mn> </msubsup> </mrow> <mn>21.15</mn> </mfrac> <mo>,</mo> </mrow> </math>

F_wis wind resistance; c_DIs emptyA gas drag coefficient; a is the windward area; u. of_aThe vehicle running speed. In the figure, G is the vehicle weight; theta is the gradient; f_fIs the rolling resistance.

Namely, observer design of the liquid filling ratio:

stage 1-maximum dissipated power braking,

<math> <mrow> <msub> <mi>W</mi> <mi>r</mi> </msub> <mo>=</mo> <mfrac> <mrow> <mi>&gamma;</mi> <mo>&CenterDot;</mo> <msub> <mi>T</mi> <mi>r</mi> </msub> <mo>&CenterDot;</mo> <mi>n</mi> </mrow> <mn>9549</mn> </mfrac> </mrow> </math>

F_r1·R＝i₁·i₂·γ·T_r

n＝a₁·u_a，

to obtain

<math> <mrow> <msub> <mi>F</mi> <mrow> <mi>r</mi> <mn>1</mn> </mrow> </msub> <mo>=</mo> <mfrac> <mrow> <mn>9549</mn> <mo>&CenterDot;</mo> <msub> <mi>W</mi> <mi>r</mi> </msub> <mo>&CenterDot;</mo> <msub> <mi>i</mi> <mn>1</mn> </msub> <mo>&CenterDot;</mo> <msub> <mi>i</mi> <mn>2</mn> </msub> </mrow> <mrow> <msub> <mi>a</mi> <mn>1</mn> </msub> <mo>&CenterDot;</mo> <mi>R</mi> <mo>&CenterDot;</mo> <msub> <mi>u</mi> <mi>a</mi> </msub> </mrow> </mfrac> <mo>=</mo> <mfrac> <msub> <mi>l</mi> <mn>1</mn> </msub> <msub> <mi>u</mi> <mi>a</mi> </msub> </mfrac> </mrow> </math>

<math> <mrow> <mi>&gamma;</mi> <mo>=</mo> <mfrac> <mrow> <mn>9549</mn> <msub> <mi>W</mi> <mi>r</mi> </msub> </mrow> <mrow> <msub> <mi>a</mi> <mn>1</mn> </msub> <mo>&CenterDot;</mo> <msub> <mi>T</mi> <mi>r</mi> </msub> <mo>&CenterDot;</mo> <msub> <mi>u</mi> <mi>a</mi> </msub> </mrow> </mfrac> <mo>,</mo> </mrow> </math>

Wherein,

<math> <mrow> <msub> <mi>l</mi> <mn>1</mn> </msub> <mo>=</mo> <mfrac> <mrow> <mn>9549</mn> <mo>&CenterDot;</mo> <msub> <mi>W</mi> <mi>r</mi> </msub> <mo>&CenterDot;</mo> <msub> <mi>i</mi> <mn>1</mn> </msub> <mo>&CenterDot;</mo> <msub> <mi>i</mi> <mn>2</mn> </msub> </mrow> <mrow> <mi>R</mi> <mo>&CenterDot;</mo> <msub> <mi>a</mi> <mn>1</mn> </msub> </mrow> </mfrac> <mo>,</mo> </mrow> </math>

wherein; gamma is the current liquid filling ratio, namely the original liquid filling ratio; n is the rotation speed; a is₁Is a conversion factor; r is the radius of the wheel; t is_rOutput torque at full charge; w_rThe method is determined according to different vehicles and different working conditions, and can be temporarily set as a fixed value; i.e. i₁、i₂The speed ratios of the gearbox and the main reducer are respectively.

Then during stage1, the driving force-running resistance equation takes the specific form:

<math> <mrow> <mi>m</mi> <msub> <mover> <mi>u</mi> <mo>.</mo> </mover> <mi>a</mi> </msub> <mo>=</mo> <mi>mg</mi> <mi>sin</mi> <mi>&theta;</mi> <mo>-</mo> <mrow> <mo>(</mo> <mi>c</mi> <mo>+</mo> <msub> <mi>ku</mi> <mi>a</mi> </msub> <mo>)</mo> </mrow> <mo>-</mo> <msubsup> <mi>bu</mi> <mi>a</mi> <mn>2</mn> </msubsup> <mo>-</mo> <mfrac> <msub> <mi>l</mi> <mn>1</mn> </msub> <msub> <mi>u</mi> <mi>a</mi> </msub> </mfrac> <mo>.</mo> </mrow> </math>

further, stage2 — maximum brake power braking:

F_r2·R＝i₁·i₂·γ·T_r，

in this process, γ ≡ 1 is used because the liquid is filled in the full range.

T_r＝λ·ρ·n²·D⁵＝a₂n²，

In the formula, rho is fluid density, and the working solution can be a mixed solution of water and glycol; lambda is performance factor; n is rotor speed; d is a profile diameter.

<math> <mrow> <msub> <mi>F</mi> <mrow> <mi>r</mi> <mn>2</mn> </mrow> </msub> <mo>=</mo> <mfrac> <mrow> <msubsup> <mi>a</mi> <mn>1</mn> <mn>2</mn> </msubsup> <mo>&CenterDot;</mo> <msub> <mi>a</mi> <mn>2</mn> </msub> <mo>&CenterDot;</mo> <msub> <mi>i</mi> <mn>1</mn> </msub> <mo>&CenterDot;</mo> <msub> <mi>i</mi> <mn>2</mn> </msub> </mrow> <mi>R</mi> </mfrac> <mo>&CenterDot;</mo> <msubsup> <mi>u</mi> <mi>a</mi> <mn>2</mn> </msubsup> <mo>=</mo> <msub> <mi>l</mi> <mn>2</mn> </msub> <msubsup> <mi>u</mi> <mi>a</mi> <mn>2</mn> </msubsup> <mo>,</mo> </mrow> </math>

Wherein,

<math> <mrow> <msub> <mi>l</mi> <mn>2</mn> </msub> <mo>=</mo> <mfrac> <mrow> <msubsup> <mi>a</mi> <mn>1</mn> <mn>2</mn> </msubsup> <mo>&CenterDot;</mo> <msub> <mi>a</mi> <mn>2</mn> </msub> <mo>&CenterDot;</mo> <msub> <mi>i</mi> <mn>1</mn> </msub> <mo>&CenterDot;</mo> <msub> <mi>i</mi> <mn>2</mn> </msub> </mrow> <mi>R</mi> </mfrac> <mo>.</mo> </mrow> </math>

during stage2, the driving force-running resistance equation takes the specific form:

<math> <mrow> <mi>m</mi> <msub> <mover> <mi>u</mi> <mo>.</mo> </mover> <mi>a</mi> </msub> <mo>=</mo> <mi>mg</mi> <mi>sin</mi> <mi>&theta;</mi> <mo>-</mo> <mrow> <mo>(</mo> <mi>c</mi> <mo>+</mo> <msub> <mi>ku</mi> <mi>a</mi> </msub> <mo>)</mo> </mrow> <mo>-</mo> <msubsup> <mi>bu</mi> <mi>a</mi> <mn>2</mn> </msubsup> <mo>-</mo> <msub> <mi>l</mi> <mn>2</mn> </msub> <msubsup> <mi>u</mi> <mi>a</mi> <mn>2</mn> </msubsup> <mo>.</mo> </mrow> </math>

further, stage 3-constant speed brake control. Wherein, stage3 is divided into two cases for analysis:

start constant speed control at any point of a.stage2, and proceed to stage 3. And respectively establishing a full liquid-filled deceleration system equation and a target partial liquid-filled constant speed system equation before and after the time t of stage 3.

<math> <mrow> <mi>m</mi> <msub> <mover> <mi>u</mi> <mo>.</mo> </mover> <mi>a</mi> </msub> <mo>=</mo> <mi>mg</mi> <mi>sin</mi> <mi>&theta;</mi> <mo>-</mo> <msub> <mi>F</mi> <mi>f</mi> </msub> <mo>-</mo> <msub> <mi>F</mi> <mi>w</mi> </msub> <mo>-</mo> <msub> <mi>F</mi> <mrow> <mi>r</mi> <mn>2</mn> </mrow> </msub> <mo>,</mo> </mrow> </math>

0＝mgsinθ-F_f-F_w-γ^{^}·F_r2，

Between two time points, if the time is short, the gradient is considered unchanged, and it can be:

<math> <mrow> <msup> <mi>&gamma;</mi> <mo>^</mo> </msup> <mo>=</mo> <mn>1</mn> <mo>+</mo> <mfrac> <mrow> <mi>m</mi> <msub> <mover> <mi>u</mi> <mo>.</mo> </mover> <mi>a</mi> </msub> </mrow> <mrow> <msub> <mi>l</mi> <mn>2</mn> </msub> <mo>&CenterDot;</mo> <msubsup> <mi>u</mi> <mi>a</mi> <mn>2</mn> </msubsup> </mrow> </mfrac> <mo>.</mo> </mrow> </math>

B. the vehicle is already at constant speed at stage3, but the slope of the road has changed. Changing the original constant speed theta into a new constant speed theta' at the moment t, and then the kinetic equation before and after the gradient change moment t is as follows:

<math> <mrow> <mi>m</mi> <msub> <mover> <mi>u</mi> <mo>.</mo> </mover> <mi>a</mi> </msub> <mo>=</mo> <mi>mg</mi> <mi>sin</mi> <msup> <mi>&theta;</mi> <mo>&prime;</mo> </msup> <mo>-</mo> <msub> <mi>F</mi> <mi>f</mi> </msub> <mo>-</mo> <msub> <mi>F</mi> <mi>w</mi> </msub> <mo>-</mo> <msub> <mi>F</mi> <mrow> <mi>r</mi> <mn>2</mn> </mrow> </msub> <mo>&CenterDot;</mo> <mi>&gamma;</mi> <mo>,</mo> </mrow> </math>

0＝mgsinθ′-F_f-F_w-F_r2·γ′，

wherein gamma is the original liquid filling ratio; γ' is the charge ratio required to maintain constant velocity on the new grade, resulting in:

<math> <mrow> <msup> <mi>&gamma;</mi> <mo>^</mo> </msup> <mo>=</mo> <mi>&gamma;</mi> <mo>+</mo> <mfrac> <mrow> <mi>m</mi> <msub> <mover> <mi>u</mi> <mo>.</mo> </mover> <mi>a</mi> </msub> </mrow> <mrow> <msub> <mi>l</mi> <mn>2</mn> </msub> <mo>&CenterDot;</mo> <msubsup> <mi>u</mi> <mi>a</mi> <mn>2</mn> </msubsup> </mrow> </mfrac> <mo>.</mo> </mrow> </math>

the two cases of A and B can be expressed by the same formula:

<math> <mrow> <msup> <mi>&gamma;</mi> <mo>^</mo> </msup> <mo>=</mo> <mi>&gamma;</mi> <mo>+</mo> <mfrac> <mrow> <mi>m</mi> <msub> <mover> <mi>u</mi> <mo>.</mo> </mover> <mi>a</mi> </msub> </mrow> <mrow> <msub> <mi>l</mi> <mn>2</mn> </msub> <mo>&CenterDot;</mo> <msubsup> <mi>u</mi> <mi>a</mi> <mn>2</mn> </msubsup> </mrow> </mfrac> <mo>.</mo> </mrow> </math>

wherein,is the current vehicle speed acceleration; u. of_aA target constant speed vehicle speed; γ is at most 1.

During stage3, the driving force-running resistance equation takes the specific form:

<math> <mrow> <mi>m</mi> <msub> <mover> <mi>u</mi> <mo>.</mo> </mover> <mi>a</mi> </msub> <mo>=</mo> <mi>mg</mi> <mi>sin</mi> <mi>&theta;</mi> <mo>-</mo> <mrow> <mo>(</mo> <mi>c</mi> <mo>+</mo> <msub> <mi>ku</mi> <mi>a</mi> </msub> <mo>)</mo> </mrow> <mo>-</mo> <msubsup> <mi>bu</mi> <mi>a</mi> <mn>2</mn> </msubsup> <mo>-</mo> <msub> <mi>l</mi> <mn>2</mn> </msub> <msubsup> <mi>u</mi> <mi>a</mi> <mn>2</mn> </msubsup> <mo>&CenterDot;</mo> <msup> <mi>&gamma;</mi> <mo>^</mo> </msup> <mo>.</mo> </mrow> </math>

in summary, the target liquid filling ratio of the liquid filling ratio observer at stage1-stage3 is:

stage1: <math> <mrow> <msup> <mi>&gamma;</mi> <mo>^</mo> </msup> <mo>=</mo> <mfrac> <mrow> <msub> <mi>W</mi> <mi>radiating</mi> </msub> <mo>&CenterDot;</mo> <mn>9549</mn> </mrow> <mrow> <msub> <mi>a</mi> <mn>1</mn> </msub> <mo>&CenterDot;</mo> <msub> <mi>u</mi> <mi>a</mi> </msub> <mo>&CenterDot;</mo> <mi>T</mi> </mrow> </mfrac> <mo>,</mo> </mrow> </math> u is greater than u_a1；

stage2：γ^{^}≡1，u_a1U is less than u and greater than u_a2；

stage3: <math> <mrow> <msup> <mi>&gamma;</mi> <mo>^</mo> </msup> <mo>=</mo> <mi>&gamma;</mi> <mo>+</mo> <mfrac> <mrow> <mi>m</mi> <msub> <mover> <mi>u</mi> <mo>.</mo> </mover> <mi>a</mi> </msub> </mrow> <mrow> <msub> <mi>l</mi> <mn>2</mn> </msub> <mo>&CenterDot;</mo> <msubsup> <mi>u</mi> <mi>a</mi> <mn>2</mn> </msubsup> </mrow> </mfrac> <mo>,</mo> </mrow> </math> u_a2Less than u.

Further, the mass estimation equation can be derived from the kinetic equation:

$m{\stackrel{.}{u}}_a=G_x-F_f-F_w-F_r,$

wherein,

F(u_a)＝F_f+F_w+F_r，

the program of this embodiment may be set by default, and two time points t are taken after each time the hydrodynamic retarder is activated₁And t₂Respectively corresponding to the velocity u_a1And u_a2Two equations are established: (the time interval is small, and the gradient is not changed within the time interval by default).

$m{\stackrel{.}{u}}_{a1}=G_x-F\left(u_{a1}\right),$

$m{\stackrel{.}{u}}_{a2}=G_x-F\left(u_{a2}\right),$

Wherein,andthe value of (a) can be obtained from a sensor; f (u)_a1) And F (u)_a2) Can be obtained from the functional relationship. It can be found that:

$m=-\frac{F\left(u_{a1}\right)+F\left(u_{a2}\right)}{{\stackrel{.}{u}}_{a1}+{\stackrel{.}{u}}_{a2}}.$

in the continuous operation time of the single hydraulic retarder, two time points can be taken for a plurality of times in a short time to predict the mass m, so that the value m is accurately obtained, and the influence on the assumption that the gradient is unchanged in a time interval is eliminated.

And then, the derivation of the hydrodynamic retarder observer is finished:

stage1:(Current vehicle speed u) is greater than u_a1；

stage2：γ^{^}≡1，u_a1Less than (current vehicle speed u) and greater than u_a2；

stage3:u_a2Less than (current vehicle speed u).

In the embodiment of the invention, as shown in fig. 4 to 7, the vehicle system without the observer needs a long time to stabilize the vehicle speed, the hydrodynamic retarder with the observer can rapidly stabilize the vehicle speed, and the fluctuation phenomenon caused by continuous iteration of the vehicle speed and the liquid filling ratio does not occur, which is beneficial to the running stability of the vehicle and the service life of the valve body.

Further, in the embodiment of the invention, referring to fig. 8 and 9, even if the quality observation is in a problem, the constant speed control of the vehicle is still not affected, and the constant speed vehicle speed required by the driver can still be constant, the observer can automatically output different gas-liquid ratio control targets to make up for the error caused by the quality observation, and further adjust the speed of the whole vehicle.

According to the automatic liquid filling ratio acquisition device for the hydraulic retarder provided by the embodiment of the invention, under different working conditions of the hydraulic retarder, the liquid filling ratio at which the hydraulic retarder is currently located is automatically output by extracting the parameters of the whole vehicle, namely, the control target of the liquid filling ratio is acquired, and automatic control and quick liquid filling ratio positioning are realized, so that the vehicle is quickly stabilized, the running stability of the vehicle is ensured, the service life of the valve body is prolonged, and the device is simple and convenient.

Any process or method descriptions in flow charts or otherwise described herein may be understood as representing modules, segments, or portions of code which include one or more executable instructions for implementing specific logical functions or steps of the process, and alternate implementations are included within the scope of the preferred embodiment of the present invention in which functions may be executed out of order from that shown or discussed, including substantially concurrently or in reverse order, depending on the functionality involved, as would be understood by those reasonably skilled in the art of the present invention.

The logic and/or steps represented in the flowcharts or otherwise described herein, e.g., an ordered listing of executable instructions that can be considered to implement logical functions, can be embodied in any computer-readable medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, processor-containing system, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions. For the purposes of this description, a "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of the computer-readable medium would include the following: an electrical connection (electronic device) having one or more wires, a portable computer diskette (magnetic device), a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disc read-only memory (CDROM). Additionally, the computer-readable medium could even be paper or another suitable medium upon which the program is printed, as the program can be electronically captured, via for instance optical scanning of the paper or other medium, then compiled, interpreted or otherwise processed in a suitable manner if necessary, and then stored in a computer memory.

It should be understood that portions of the present invention may be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, the various steps or methods may be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, any one or combination of the following techniques, which are known in the art, may be used: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, an application specific integrated circuit having an appropriate combinational logic gate circuit, a Programmable Gate Array (PGA), a Field Programmable Gate Array (FPGA), or the like.

It will be understood by those skilled in the art that all or part of the steps carried by the method for implementing the above embodiments may be implemented by hardware related to instructions of a program, which may be stored in a computer readable storage medium, and when the program is executed, the program includes one or a combination of the steps of the method embodiments.

In addition, functional units in the embodiments of the present invention may be integrated into one processing module, or each unit may exist alone physically, or two or more units are integrated into one module. The integrated module can be realized in a hardware mode, and can also be realized in a software functional module mode. The integrated module, if implemented in the form of a software functional module and sold or used as a stand-alone product, may also be stored in a computer readable storage medium.

The storage medium mentioned above may be a read-only memory, a magnetic or optical disk, etc.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made in the above embodiments by those of ordinary skill in the art without departing from the principle and spirit of the present invention.

Claims (10)

1. The automatic liquid filling ratio acquiring method of the hydrodynamic retarder is characterized by comprising the following steps of:

establishing a driving force-running resistance equation, wherein the driving force-running resistance equation includes: the driving force, the wind resistance, the rolling resistance and the output braking force of the hydraulic retarder;

judging the working state of the hydraulic retarder, wherein the working state comprises a deceleration initial control state, a deceleration later control state and a constant speed stage control state;

if the control state is the initial deceleration control state, obtaining a first liquid filling ratio of the hydraulic retarder according to the driving force-running resistance equation and the maximum heat dissipation power of the hydraulic retarder;

if the control state is the later deceleration control state, obtaining a second liquid filling ratio of the hydraulic retarder according to the driving force-running resistance equation and the maximum braking power of the hydraulic retarder;

and if the control state is the constant speed stage control state, obtaining a third liquid filling ratio of the hydraulic retarder according to the driving force-running resistance equation and the current liquid filling ratio and gradient value of the hydraulic retarder.

2. The method for automatically acquiring the filling ratio of the hydrodynamic retarder according to claim 1, wherein the driving force-driving resistance equation has a formula:

$m{\stackrel{.}{u}}_a=G_x-F_f-F_w-F_r,$

wherein G is_xIs the driving force, F_wTo the wind resistance, F_fFor said rolling resistance, F_rAnd outputting the braking force for the hydraulic retarder.

3. The method for automatically acquiring the liquid filling ratio of the hydraulic retarder according to claim 2, wherein the first liquid filling ratio of the hydraulic retarder is as follows:

<math> <mrow> <msup> <msub> <mi>&gamma;</mi> <mn>1</mn> </msub> <mo>^</mo> </msup> <mo>=</mo> <mfrac> <mrow> <msub> <mi>W</mi> <mi>radiating</mi> </msub> <mo>&CenterDot;</mo> <mn>9549</mn> </mrow> <mrow> <msub> <mi>a</mi> <mn>1</mn> </msub> <mo>&CenterDot;</mo> <msub> <mi>u</mi> <mi>a</mi> </msub> <mo>&CenterDot;</mo> <mi>T</mi> </mrow> </mfrac> <mo>,</mo> </mrow> </math>

wherein, W_radiatingIs the maximum heat dissipation power, a₁As a conversion factor, u_aAnd T is the running speed of the vehicle, and T is the output torque of the hydraulic retarder.

4. The method for automatically acquiring the liquid filling ratio of the hydraulic retarder according to claim 2, wherein the second liquid filling ratio γ of the hydraulic retarder₂ ^{^}≡1。

5. The method for automatically acquiring the liquid filling ratio of the hydraulic retarder according to claim 2, wherein the third liquid filling ratio of the hydraulic retarder is as follows:

<math> <mrow> <msup> <msub> <mi>&gamma;</mi> <mn>3</mn> </msub> <mo>^</mo> </msup> <mo>=</mo> <mi>&gamma;</mi> <mo>+</mo> <mfrac> <mrow> <mo>-</mo> <mfrac> <mrow> <mi>F</mi> <mrow> <mo>(</mo> <msub> <mi>u</mi> <mrow> <mi>a</mi> <mn>1</mn> </mrow> </msub> <mo>)</mo> </mrow> <mo>+</mo> <mi>F</mi> <mrow> <mo>(</mo> <msub> <mi>u</mi> <mrow> <mi>a</mi> <mn>2</mn> </mrow> </msub> <mo>)</mo> </mrow> </mrow> <mrow> <msub> <mover> <mi>u</mi> <mo>.</mo> </mover> <mrow> <mi>a</mi> <mn>1</mn> </mrow> </msub> <mo>+</mo> <msub> <mover> <mi>u</mi> <mo>.</mo> </mover> <mrow> <mi>a</mi> <mn>2</mn> </mrow> </msub> </mrow> </mfrac> <msub> <mover> <mi>u</mi> <mo>.</mo> </mover> <mi>a</mi> </msub> </mrow> <mrow> <msub> <mi>l</mi> <mn>2</mn> </msub> <mo>&CenterDot;</mo> <msup> <msub> <mi>u</mi> <mi>a</mi> </msub> <mn>2</mn> </msup> </mrow> </mfrac> <mo>,</mo> </mrow> </math>

gamma is the current fill ratio, u_a1Is a first vehicle speed u_a2In order to set the second vehicle speed to the second vehicle speed,is a first acceleration corresponding to the vehicle at the first vehicle speed,is a second acceleration corresponding to the vehicle at the second vehicle speed,as the current acceleration of the vehicle, /)₂At a predetermined value, u_aIs the target constant speed vehicle speed of the vehicle.

6. The utility model provides a liquid filling ratio automatic acquisition device of hydraulic retarber which characterized in that includes:

an establishment module for establishing a driving force-running resistance equation, wherein the driving force-running resistance equation includes: the driving force, the wind resistance, the rolling resistance and the output braking force of the hydraulic retarder;

the judging module is used for judging the working state of the hydraulic retarder, wherein the working state comprises a deceleration initial control state, a deceleration later control state and a constant speed stage control state;

and the acquisition module is used for obtaining a first liquid filling ratio of the hydraulic retarder according to the driving force-driving resistance equation and the maximum heat dissipation power of the hydraulic retarder when the control state is in the initial deceleration control state, obtaining a second liquid filling ratio of the hydraulic retarder according to the driving force-driving resistance equation and the maximum braking power of the hydraulic retarder when the control state is in the late deceleration control state, and obtaining a third liquid filling ratio of the hydraulic retarder according to the driving force-driving resistance equation, the current liquid filling ratio of the hydraulic retarder and the gradient value when the control state is in the constant speed stage control state.

7. The automatic liquid filling ratio acquisition device for the hydrodynamic retarder according to claim 6, wherein the driving force-driving resistance equation has a formula:

$m{\stackrel{.}{u}}_a=G_x-F_f-F_w-F_r,$

wherein G is_xIs the driving force, F_wTo the wind resistance, F_fFor said rolling resistance, F_rAnd outputting the braking force for the hydraulic retarder.

8. The automatic liquid filling ratio acquisition device for the hydraulic retarder according to claim 7, wherein the first liquid filling ratio of the hydraulic retarder is:

<math> <mrow> <msup> <msub> <mi>&gamma;</mi> <mn>1</mn> </msub> <mo>^</mo> </msup> <mo>=</mo> <mfrac> <mrow> <msub> <mi>W</mi> <mi>radiating</mi> </msub> <mo>&CenterDot;</mo> <mn>9549</mn> </mrow> <mrow> <msub> <mi>a</mi> <mn>1</mn> </msub> <mo>&CenterDot;</mo> <msub> <mi>u</mi> <mi>a</mi> </msub> <mo>&CenterDot;</mo> <mi>T</mi> </mrow> </mfrac> <mo>,</mo> </mrow> </math>

wherein, W_radiatingIs the maximum heat dissipation power, a₁As a conversion factor, u_aAnd T is the running speed of the vehicle, and T is the output torque of the hydraulic retarder.

9. The automatic liquid filling ratio acquisition device for the hydrodynamic retarder as defined in claim 7, wherein the second liquid filling ratio γ of the hydrodynamic retarder₂ ^{^}≡1。

10. The automatic liquid filling ratio acquisition device for the hydraulic retarder according to claim 7, wherein the third liquid filling ratio of the hydraulic retarder is:

<math> <mrow> <msup> <msub> <mi>&gamma;</mi> <mn>3</mn> </msub> <mo>^</mo> </msup> <mo>=</mo> <mi>&gamma;</mi> <mo>+</mo> <mfrac> <mrow> <mo>-</mo> <mfrac> <mrow> <mi>F</mi> <mrow> <mo>(</mo> <msub> <mi>u</mi> <mrow> <mi>a</mi> <mn>1</mn> </mrow> </msub> <mo>)</mo> </mrow> <mo>+</mo> <mi>F</mi> <mrow> <mo>(</mo> <msub> <mi>u</mi> <mrow> <mi>a</mi> <mn>2</mn> </mrow> </msub> <mo>)</mo> </mrow> </mrow> <mrow> <msub> <mover> <mi>u</mi> <mo>.</mo> </mover> <mrow> <mi>a</mi> <mn>1</mn> </mrow> </msub> <mo>+</mo> <msub> <mover> <mi>u</mi> <mo>.</mo> </mover> <mrow> <mi>a</mi> <mn>2</mn> </mrow> </msub> </mrow> </mfrac> <msub> <mover> <mi>u</mi> <mo>.</mo> </mover> <mi>a</mi> </msub> </mrow> <mrow> <msub> <mi>l</mi> <mn>2</mn> </msub> <mo>&CenterDot;</mo> <msup> <msub> <mi>u</mi> <mi>a</mi> </msub> <mn>2</mn> </msup> </mrow> </mfrac> <mo>,</mo> </mrow> </math>

gamma is the current fill ratio, u_a1Is a first vehicle speed u_a2In order to set the second vehicle speed to the second vehicle speed,is a first acceleration corresponding to the vehicle at the first vehicle speed,is a second acceleration corresponding to the vehicle at the second vehicle speed,as the current acceleration of the vehicle, /)₂At a predetermined value, u_aIs the target constant speed vehicle speed of the vehicle.