RU2298125C1 - Differential hydromechanical variable-speed drive - Google Patents

Abstract

FIELD: mechanical engineering.

SUBSTANCE: variable-speed drive comprises two differential stages connected in series. The differential sage whose shaft is connected with the engine is the input shaft of the variable-speed drive and is made of a differential mechanism. The second differential stage is a hydraulic differential converter provided with two planet rows defined by the kinematical links of multi-gearing hydraulic pump and hydraulic motor provided with different gear ratios . The axles of the satellites of the first and second differential stages are mounted inside the housing . The housing is set in bearings inside the crankcase of the variable-speed drive and represents a carrier for both of the differential stages. The carrier is provided with the free running clutch.

EFFECT: enhanced efficiency.

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Description

The invention relates to gears of continuously variable gears and can be used in mechanical engineering, in particular, transport mechanical engineering.

The differential hydromechanical variator is designed for automatic stepless conversion of rotational motion between the engine shaft and the shaft of the working body of machines and mechanisms in order to ensure the optimal mode of joint operation of the engine and the variator with an arbitrary value of the external load on the working body.

A device is known that is the closest in combination of features to the claimed invention, for stepless changes in torque and its smooth transmission to the drive wheels.

A known device, a volumetric hydromechanical transmission with external power sharing (OGMP), is a single-circuit or dual-circuit transmission, respectively, with one or two differentials and volumetric hydraulic transmission. The power supplied to the OGMP is divided into two flows through mechanical and hydraulic links, and only a part (usually less) is transmitted to the hydraulic machines. Therefore, in comparison with the volumetric hydraulic transmission, the OGMP has a higher efficiency at the same capacities and control ranges [1]. Single-circuit OGMP consists of a volumetric hydraulic transmission and a differential mechanism with mixed or external gearing. Depending on the location of the differential link with respect to the volumetric hydraulic transmission, the OGMP is distinguished with a differential link at the input or a differential link at the output.

The power from the master to the driven shaft of the OGMP is transmitted in two streams. The first power stream is transmitted through the sun gear to the satellites and then to the carrier. Here, only mechanical power losses exist. The second power flow is transmitted to an adjustable hydraulic pump, then to an unregulated or adjustable hydraulic motor and through satellites to a carrier. Here, power is lost in the hydrostatic transmission (GOP). The main share of power losses is accounted for by GOP.

Significant disadvantages of single-circuit OGMP are the need to control hydrostatic transmission, which complicates the design through the use of an active control system, and a limited range of automatic control

R = i _max / i _min ,

where i _max - the maximum gear ratio OGMP;

i _min - the minimum gear ratio OGMP.

An increase in the control range is achieved in the double-circuit OGMP with two differentials and hydrostatic transmission, the designs of which are performed according to three schemes: with parallel, serial and parallel-serial connection of differentials. The most common is a circuit with a parallel connection of differentials, in which all the power that does not pass through the hydraulic transmission is transmitted from the drive shaft to the driven one by two parallel flows, and the power flow converter is a hydrostatic transmission with a differential output mechanism.

In order to avoid power circulation, the gear ratio of the entire gear i lies between i ₀₂ and i ₀₁ , where i ₀₁ , i ₀₂ is the gear ratio of the first and second differentials, respectively, when the link associated with the hydraulic transmission is inhibited. When | i ₀₁ |> | i ₀₂ |, i.e. i ₀₁ = i _max , i ₀₂ = i _min regulation range R = i _max / i _min = i ₀₁ / i ₀₂ .

Common disadvantages for all schemes are the limited range of regulation, the complexity of the design, due to the use of expensive and complex adjustable hydraulic drive and automatic control system.

The task to which the invention is directed is to provide automatic, without the use of control systems, torque control on the output shaft, depending on changes in external load and the range of regulation of the variator

i _var = 1 / i _ass ÷ 1,

where i _var is the gear ratio of the variator;

i _ass - a given gear ratio.

When carrying out the invention, the following technical results can be obtained:

- increase in efficiency;

- a range of automatic control, covering the entire spectrum of the speed of the output shaft of the variator from its minimum specified value at maximum torque to a speed equal to the frequency of rotation of the motor shaft, and torque equal to the engine torque;

- improving the fuel, economic and environmental characteristics of an internal combustion engine when working together with a hydromechanical differential variator;

- internal automatism that does not require a solution to the problem of management logistics;

- the possibility of engine braking;

- silent operation, smooth running and constant traction on the drive wheels;

- the ability to quickly change operating modes;

- motor protection in acceleration mode and "stop mode" from overloads.

The problem is solved in that the device consists of two series-connected differential stages. The differential stage, the input shaft of which is connected to the engine and is the input shaft of the variator, is a mechanical differential mechanism, the internal gear ratio of which can have different values. The second differential stage is a hydraulic differential converter having two planetary gear sets, each of which is formed by the kinematic links of a multi-gear hydraulic pump and a hydraulic motor with different values of internal gear ratios. The axis of the satellites of the first and second differential stages are installed in the housing common to both differential stages. A housing mounted on bearings in the CVT housing serves as a common carrier for both differential stages, on which a freewheel is mounted. In addition to the mechanical connection due to the presence of a common carrier, there is a dynamic hydraulic connection between the planetary rows of the hydraulic differential converter, in the circuit of which an automatic bypass and adjustable valve are installed.

Unlike the prototype, in which the converter of two power flows of the input differential consists of kinematically connected hydrostatic and differential gears, the present invention solves the problem of converting the power flows of the input differential using a hydraulic differential converter, which allows to achieve the above technical results.

The principle of operation of the hydromechanical differential variator is based on the equality of the interaction of the oppositely directed moments generated on the carrier as a result of the action of the internal forces of the differential stages, and the automatic change of pressure p and the flow rate of the working fluid Q through the hydraulic pump and hydraulic motor, which occurs as a result of changes in the speed of the links of the differential stages when changing the speed of the output shaft relative to the constant speed of the input shaft.

Figure 1 presents the kinematic diagram of the design of the proposed differential hydromechanical variator.

Figure 2 presents the dimensionless characteristic of the change in fluid flow Q and pressure p in function

i _var = n _II / n _I ,

where Q _{max slave} is the maximum flow rate;

p _max is the maximum pressure;

p ₀ is the pressure at i _var = 1;

K = 1 / i _ass is the transformation ratio.

In the kinematic diagram of figure 1 are indicated:

And ₁ is a mechanical differential mechanism; And ₂ - a hydraulic differential converter; 1 - input link of the differential mechanism, it is the input shaft of the variator; 2-2 '- satellites; 3-3 '- the output link of the differential mechanism, it is also the input link of the hydraulic differential transducer; 4 - carrier (case) of the variator; 5 and 6 - driven wheels, respectively, of a hydraulic pump and a hydraulic motor; 7 - the driven shaft of the hydraulic motor, it is the output shaft of the variator; 8 - controlled valve; 9 - automatic bypass valve; 10 - hydraulic pump; 11 - hydraulic motor; 12 - freewheel; 13 and 16, respectively, the inlet windows of the hydraulic pump and the hydraulic motor; 14 and 15, respectively, the outlet windows of the hydraulic pump and the hydraulic motor; 17 - an expansion tank; 18 - annular channel; 19 - a case of a variator; 20 - filter; 21 - heat exchanger.

The housing 4 of the differential hydromechanical variator is supported by bearings mounted in an oil-filled crankcase 19. To compensate for thermal expansion of the oil, the crankcase has an expansion tank 17. The first differential stage of the variator is a mechanical differential mechanism composed of input shaft 1, satellites 2-2 ', output link 3-3 'and carrier 4. The second differential stage of the variator is a hydraulic differential converter formed by carrier 4, many ennymi toothed hydraulic pump 10 with moving axles and driven wheels 5, which number should be at least two, and hydraulic motor 11 with moving axles and driving wheels 6, the number of which should be at least two. The hydraulic pump and the hydraulic motor have inlet 13 and 16, exhaust 14 and 15 windows, the number of which is equal to the number of driven wheels of the hydraulic pump and the leading hydraulic motor.

An automatic bypass valve 9 and a controlled valve 8 are installed in the hydraulic annular channel 18. A freewheel 12 is installed between the carrier 4 and the crankcase 19, a filter 20 is installed on the inlet windows of the hydraulic pump, a heat exchanger 21 is installed in the lower part of the crankcase 19.

When the carrier 4 is stationary, the torque M ₁ from the external energy source is transmitted to the input link 1 of the differential mechanism A ₁ , which rotates with a rotation speed n ₁ , and is transmitted through the planetary gears 2-2 'to the gear 3 of the kinematic link 3-3'. When this link 3-3 'rotates in the same direction as the input link 1. The rotation of the link 3-3' and gears 5 creates a flow of working fluid, determined by the parameters of the equation

where M _{3-3 '} = M _GN - the moment on the input shaft of the hydraulic pump;

p is the fluid pressure, Pa;

V _GN - the working volume of the hydraulic pump, m ³ .

Drove 4 receives the reactive moment from the mechanical differential mechanism A ₁ , equal to M _4A1 = -M ₁ (1-i ₁₃ ), directed in the direction opposite to the direction of rotation of the input link 1.

When using a gear pump with two or more driven wheels, the force exerted by the driving gear 3 'on the gear 5, which receive the peripheral moment in the process of displacing the working fluid, when it is brought to the center of the gear 5 creates a moment on the carrier 4, defined as M _4A2 = -M ₁ i ₁₃ (1-i _3'5 ).

The sum of the moments M _4A1 and M _4A2 is ∑M ₄ = M _4A1 + M _4A2 = -M ₁ (1-i ₁₃ i _3'5 ) and has a direction that coincides with the direction of rotation of the input link 1.

The flow of the working fluid through the outlet windows of the hydraulic pump 14 enters the annular channel 18 and through the inlet windows of the hydraulic motor 75 into its working cavities, formed by the cavities of the gears 6 and 7. The torque on the output shaft of the hydraulic motor is determined by the equation

M _GM = pV _GM / 2π = M _GN i _g = -M ₁ i ₁₃ i _g = M _II ,

where p is the fluid pressure, Pa;

V _GM - the working volume of the hydraulic motor, m ³ ;

- гидравлическое передаточное число.

- hydraulic gear ratio.

, откуда

.Hydraulic gear ratio from carrier balance condition 4

from where

.

. При |М_C|>|-М_II| разница моментов на водиле 4 воспринимается муфтой свободного хода 12. При уменьшении числа оборотов выходного вала под действием нагрузки, превышающей расчетную, до n_II=0 давление в кольцевой полости растет до величины давления срабатывания автоматического перепускной клапана 9 и разность расходов жидкости через гидронасос и гидромотор перетекает из кольцевого канала 18 во внутреннюю полость корпуса 19. Ввиду значительного повышения температуры рабочей жидкости при перетекании ее через щели клапана 9 такой режим работы допускается кратковременно в процессе трогания транспортного средства с места.Drove 4, which is common to two differential stages, in the presence of a moment of resistance on the output shaft of 7 M _C = -M _II is in equilibrium and its number of revolutions is n ₄ = 0, and the number of revolutions of the output shaft of the variator

. When | M _C |> | -M _II | the difference in moments on carrier 4 is perceived by the freewheel 12. When the number of revolutions of the output shaft under the influence of a load exceeding the calculated one decreases to n _II = 0, the pressure in the annular cavity rises to the pressure of the automatic bypass valve 9 and the difference in fluid flow through the hydraulic pump and hydraulic motor flows from the annular channel 18 into the internal cavity of the housing 19. Due to a significant increase in the temperature of the working fluid when it flows through the slots of the valve 9, this mode of operation is allowed to be short temporarily in the process of starting a vehicle from a place.

до n_II=n_I, что и определяет диапазон автоматического регулирования вариатора i_var=1/i_зад÷1. При этом происходит перераспределение потоков мощности по гидравлическому и механическому контуру, и при n_II=n_I вся мощность передается по механическому контуру.When the load on the output shaft II decreases, the reactive moment on the carrier 4 from the side of the hydraulic motor decreases, the hydraulic power flow decreases while the mechanical total moment ∑M ₄ , formed by the operation of the differential stages A ₁ and A ₂ , at a constant number of revolutions of the input shaft I transmits power through a parallel mechanical power flow. The difference between the total moment and the reactive moment leads to the rotation of the carrier 4 in the same direction as the input I and output II shafts, and the number of revolutions of the output shaft II increases from

to n _II = n _I , which determines the range of automatic variator control i _var = 1 / i _ass ÷ 1. When this happens, the redistribution of power flows along the hydraulic and mechanical circuit, and when n _II = n _I all the power is transmitted along the mechanical circuit.

When the speed of rotation of the output shaft n _II = n _{I, the} relative speeds of all links are equal to zero, therefore Q = 0. When the speed n _II changes, the carrier speed n ₄ and, accordingly, the speed of the hydraulic pump and hydraulic motor links relative to carrier 4. The speed of the output shaft in the range from n _II = 1 / i _rear to n _II = 0 changes when n ₄ = 0. When n ₄ = 0, the flow rate of the working fluid Q = n _{3 '} V _GN = n _II V _GM and pressure p = p _max . In connection with the redistribution of the power flow with a change in the speed of the output shaft, the parameters of the hydraulic power flow p and Q change in accordance with the graph depicted in figure 2.

In order to ensure a constant pressure p _max in the acceleration range when Q _GN ≠ Q _GM , an automatic bypass valve 9 is provided in the hydraulic system. In addition, a controlled valve 8 is provided in the hydraulic system, the purpose of which is to break the flow of the working fluid in the hydraulic circuit, which is necessary when starting the engine, starting off the vehicle, disconnecting the engine from the transmission while driving.

Compared with the prototype, automatic stepless control of kinematic and power parameters is carried out in the complete absence of any control system, and simplicity of design options is achieved.

The increase in the efficiency is due to the reduction of hydrostatic losses, due to the lack of local resistance in the controls, small values of the flow length and the speed of the working fluid in it.

The reversibility of rotary hydraulic machines under the action of the load from the output shaft provides the possibility of engine braking.

The damping properties of the hydraulic circuit determine the quiet operation, smooth running and constant traction on the drive wheels.

The low inertia of the rotating parts at a low pressure level and, accordingly, the small mass of the variator housing allows for a quick change of the operating mode.

A freewheel mounted on the carrier shaft and an automatic bypass valve in the hydraulic circuit protect the engine in acceleration mode and "stop mode" from overloads.

A comparative analysis of the design composition of automatic transmissions, V-chains and torroid variators produced by the modern automotive industry in different countries shows a high degree of design and technological continuity with respect to the existing production of gears and hydraulic machines, a high degree of unification, a significantly lower cost of materials and labor costs and, accordingly much lower cost.

In the automotive industry, differential hydromechanical variators used as automatic transmissions, when working together with the engine, allow the latter, when the external load varies over the entire range, to work in the region of equal power mode, which leads to an optimal degree of power use and, consequently, to a significant reduction in consumption fuel.

Achieved technical results determine the multifunctional use of the invention in all areas of engineering.

Information sources

1. Hydropneumatic automation and hydraulic drive of mobile machines. Volumetric hydraulic and pneumatic machines and gears. Ed. Guskova V.V. - Mn .: Vysh. school., 1987. - S.212-221.

Claims (1)

A differential hydromechanical variator, consisting of kinematically connected input differential mechanism and a converter of its parallel power flows, comprising an input link that is an output link of a differential mechanism and an output link that is an output link of a converter, characterized in that the power flow converter is a hydraulic differential mechanism, having two planetary rows, each of which is formed by multi-gear kinematic links a hydraulic pump and a hydraulic motor with different values of the internal gear ratios, the axis of the satellites of the first and second differential stages are installed in a housing that is common for both differential stages, which is mounted on bearings in the variator housing and serves as a common carrier for both differential stages with a freewheel installed on it, and in addition to the mechanical connection due to the presence of a common carrier, a dynamic hydraulic th connection to the circuit which automatic bypass and control valve.

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