EA039372B1 - System of the hill start assist for a truck and a road train without rolling back - Google Patents

Abstract

The invention relates to the field of transport machine building, in particular to the hill start assist system (SAS) for vehicles with no rolling back. Basis of the hardware platform of the hill start assist system developed is the ABS modulator (Anti-lock Braking System), which controls the pressure of compressed air in the working brake chamber upon maintaining the vehicle on a hill. The advantages of this vehicle hill start assist system the over the proposed well-known auto manufacturers are as follows: it does not require installation of additional complex elements or systems due to the use of components available on board the vehicle, which improves competitive capacity of the product; it allows to obtain a high quality process of the brake chamber pressure control and, consequently, the braking torque developed on wheels. At this time, the dynamic load of transmission elements reduces due to adjusting the transmission braking torque increase with the decrease in the braking torque developed on wheels. The invention allows to retrofit the automated mechatronic powertrain control system with a function of hill start assist by programming the ECU (electronic control unit) of ABS.

Description

The invention relates to the field of transport engineering, in particular to a start assist system (SPT) of vehicles from a place on the rise without rolling back.

The well-known SPT system for trucks and road trains was developed by specialists from the Volvo Group [1]. When detecting zero vehicle speed (less than 3 km / h), tilt angle and movement of the gas pedal, the electronic control unit (ECU) of the transmission sends a signal to the anti-lock braking system (ABS) ECU to activate the SPT. After activation of the SPT in the brake chambers of all wheels or several wheels (including trailer wheels), a pressure of 0.48-0.52 MPa is maintained. This SPT system has some advantages, such as simplicity in the operation algorithm, high reliability and durability.

This system also has a number of disadvantages:

the pressure in the brake chambers of the wheels during the operation of the SPT is constant (0.48-0.52 MPa), this is not optimal for all modes of operation of the car, for example, when equipped and at a small angle of inclination and when loaded at a large angle of inclination;

the pressure in the brake chambers decreases immediately after the SPT is turned off, which causes large dynamic loads on the transmission elements;

additional non-standard elements are required: comparative valves, a logic valve, a pressure reducing valve, as a result of which the price of products increases, the reliability of the system and its competitiveness decrease.

Specialists from Fuji Jukogyo (JP) proposed the principle, method and algorithm for starting a car on a hill using a transmission brake [2].

But it is known that the transmission brake has a small power, and, consequently, a small braking torque. Due to the ease of operation and compactness in general, when integrated into a mechatronic powertrain control system, this proposal is most often suitable for cars and light trucks.

There is an SPT on the slope with a freewheel installed after the clutch release bearing on the input shaft of the gearbox as a vehicle holder against rolling away on the slope [3]. This is the simplest start assist system, but has some disadvantages such as reduced overall transmission efficiency, increased transmission noise and production cost.

Closest to the claimed technical solution in terms of essential features and the achieved technical result is a brake system with the SPT function, the feature of which is the absence of additional elements [4]. To perform the SPT function, mainly modular systems are used, integrated in the braking system as ABS and PBS (traction control system). After the brake ECU has received information about the zero speed of the vehicle, the angle of the road, the zero degree of depression of the main brake valve, the activation of the SPT function will be carried out.

In this case, the ABS valves switch to the maximum pressure hold state carried out by the driver during the last braking period;

PBS valves switch to open and connect the ABS modulators to the receiver;

the maximum pressure is maintained in the brake chamber, which is typical for the period of the last braking before the activation of the SPT, and the value of this pressure is recorded in the memory of the ECU by the brake system. This pressure keeps the vehicle uphill without rolling back. The pressure in the brake chambers is released after 2-3 s. After the ECU determines that the vehicle speed is greater than 3 km / h, the SPT function is disabled and the system will operate normally.

The system has a number of advantages:

no additional equipment is required during the operation of the SPT, this reduces the price of the product itself, increases the reliability and durability of the system;

during the operation of the SPT, the pressure in the brake chamber is maintained, set by the driver during the last braking. At the same time, dynamic loads on the transmission elements are partially reduced when starting the car, tk. the driver, to some degree of accuracy, estimates the weight condition of the car and the angle of inclination of the lift.

The disadvantage of this SPT system is the inaccurate and poor-quality organization of the pressure relief process in the brake chamber in the transition process when starting the car on a hill.

The objective of the invention is to facilitate the process of driving a truck and a road train due to the full automatic control of the power unit and the brake and reducing the dynamic loading of transmission elements when starting off on a hill due to the qualitative organization of the pressure relief process in the brake chamber by increasing the torque in the transmission during the transient . This increases the safety of the car and increases the durability of power units.

The problem is solved by the fact that the system of assistance to start a truck or road train from a place on the rise without rolling back, containing a pneumatic modulator of the anti-lock braking system with

- 1 039372 electronic control unit, dual-line valve, solenoid valve, pressure sensor in the brake chamber, wheel speed sensor, road inclination sensor and vehicle frame position sensor, to solve the problem, the required developed braking torque on the wheels when starting the car from a place on the rise controls according to the torque of the transmission and the resistance to the movement of the car back, while the regulation of the braking torque is carried out by controlling the pressure of compressed air in the brake chamber using a pneumatic modulator of the anti-lock braking system using a time-pulse signal with individual parameter settings at each cycle of operation of the electronic control unit of the anti-lock braking system in real time.

The claimed technical solution is illustrated by drawings, where Fig. 1 is a schematic diagram of a mechatronic control system for a power unit and a vehicle brake;

fig. 2 - the principle of regulating the braking torque when starting the car from a place on the rise without rolling back.

Starting the car from a place on the rise without rolling away occurs as follows: by pressing the brake pedal, the driver first selects the driving mode when starting off. After the selector 2 of the driving modes is moved to position D (drive), the operator acts on the accelerator pedal 3, releasing the brake pedal 4. Immediately after receiving information about the zero position of the brake pedal, the zero speed of the vehicle from the sensor 9 of the wheel speed 10 and the positive angle of inclination of the road along the desired direction of vehicle movement from the road inclination sensor 13, the ABS ECU sends a control signal to open the solenoid valve 5 to supply compressed air from the cylinder 1 through the dual-line valve 7 to the brake chamber 8, preventing the vehicle from moving backward. The following actions are carried out simultaneously:

The transmission ECU generates a signal to turn off the dry friction clutch, after which the required gear is selected and engaged;

The engine ECU provides a fuel control signal, thereby providing a certain speed of the crankshaft at the moment the start gear is engaged;

The ABS ECU sends a signal to the pneumatic modulator 6 to reduce the pressure in the brake chamber 8 to the required value according to the signals from the road inclination sensor 13 and the vehicle frame position sensor 11.

After engaging the desired gear, setting the desired engine speed and the desired pressure in the brake chambers, the transmission ECU generates a signal to engage the clutch at a preliminary pace. In parallel, the ABS ECU sends a control signal to the pneumatic modulator 6 to relieve pressure in the brake chamber 8 in the course of increasing the transmitted torque through the clutch.

In the event that the ABS pneumatic modulator is used as an assistant to the hill-start assist system, the pressure in the brake chambers, and, consequently, the braking torque developed by the wheel mechanisms to keep the car on the rise, will continuously decrease to a minimum for a certain interval of time and for a certain law, the nature of which will depend on the actual value of the engine torque transmitted by the friction clutch to the transmission during hill starting. In order to achieve the desired braking torque reduction law, the ABS ECU sends a control signal with the required opening and closing times to the exhaust solenoid valve while holding the high voltage level to the intake solenoid valve. In this case, the electromagnetic (pilot) valves of the ABS pneumatic modulator can be controlled based on a low-frequency modulated VIM signal, including with individual parameter settings.

The process of controlling the ABS pneumatic modulator when working in the hill start assistance system without rolling away is divided into two stages.

The first stage: depressurization in the brake chamber from the nominal (nominal pressure in the brake system) to the required value for the resistance to the slope of the road. The pressure value in the brake chamber is recorded by the pressure sensor 12 .

The second stage: depressurization in the brake chamber from the required value to the atmospheric level according to a certain law, depending on the rate of engagement of the clutch by enumerating the time of opening and closing the exhaust solenoid valve of the ABS pneumatic modulator.

Depending on the driver's desired starting speed, which is determined by the speed at which the gas pedal is depressed, the transmission ECU pre-calculates the clutch engagement rate and, consequently, the transmission torque growth rate. Then, according to the value of the angle of inclination of the road and the mass of the car, the rise time t _pac of the torque to the value of M _under - Μψ is determined (see for. 1). During this time, the brake torque (or pressure in the brake chamber) should drop from the required value to zero as the transmission torque increases.

The condition for the failure-free movement of the car backward is described by the inequality

- 2 039372

^{where _ _}

M _under , Μψ - moments of resistance, respectively, lifting and rolling;

M _trans - torque in the transmission;

M _tor - braking torque on the wheels;

Ga is the total weight of the vehicle;

r ₀ - wheel rolling radius without slipping;

f is the coefficient of rolling resistance;

α - the angle of inclination of the road;

τ - preliminary rate of engagement of the clutch;

_pcam - pressure in the brake chamber.

The optimal value of the braking torque M _tor to ensure the conditions for the trouble-free movement of the car back when starting off is M _under - Μψ - M _trans and is described by line 14. Due to the change in the characteristics of the elements of the brake system during the operation of the car, the estimated range of regulation of the braking torque is taken, limited by two lines 14 and 15. In this case, the upper limit of the braking torque (line 15) is determined based on the line 14 with an increase of 10% of the lower limit.

The process of controlling the braking torque on the wheel, the essence of which is reflected in Fig. 2 is carried out by comparing the value of the controlled parameter with the upper or lower limit. If at a given time the braking torque is at the lower limit (line 14), then it is held for a while until it reaches the upper limit (line 15). After that, the braking torque is reduced to the lower limit and the control process is repeated until zero braking torque. When applying a linear dependence of the braking torque on the wheel on the pressure in the brake chamber, the task of regulating the braking torque turns into controlling the pressure in the brake chamber. The holding or reducing braking torque phase at time t1 or t ₂ corresponds to the closing or opening of the pneumatic modulator exhaust solenoid valve at time t1 or t ₂ (FIG. 2). The proposed technical solution will improve traffic safety by facilitating the process of driving when starting off on the rise;

durability of transmission elements by reducing their dynamic loading when starting the car from a place on the rise.

List of used sources.

1. Hill start assist system: pat. US8078378B2 USA, Int. Cl. G06F 19/00 (2011.01)

I A. M. Bradley, Assignee: Volvo Group North America LLC, Date of Patent: 12/13/2011.

2. Hill hold control apparatus for vehicle: pat. 6616572B2 USA, Int. Cl.7 F16H

61/22 / K. Suzuki, Assignee: Fuji Jukogyo Kabushiki Kaisha, Date of Patent: 09/09/2003.

3.Vehicle hill-start assistant system: pat. 203391616U CN, Int. Cl. B60K 17/02 (2006.01) / CAI WEIMO [et al.], Assignee: Dongfeng Motor Co., Ltd., Date of Patent: 1/15/2014.

4. Pressure-medium-activated brake device of a vehicle having control routines implemented in a brake controller unit, of a hill start assistant function or creep suppression function: pat. US9193338B2 USA, Int. Cl. B60T 8/175 (2006.01), B60T 7/12 (2006.01) / A. Schaefers, M. Adnan , Assignee: Knorr-Bremse Systeme fuer Nutzfahrzeuge GmbH, Date of Patent: 24.11.2015.

CLAIM

Claims (1)

CLAIM Assistance system for starting a truck or road train from a place on a hill without rolling away, containing a pneumatic modulator (6) of an anti-lock braking system with an electronic control unit, a dual-line valve (7), a solenoid valve (5), a pressure sensor in the brake chamber (12), a sensor ( 9) wheel speed (10), road inclination sensor (13) and vehicle frame position sensor (11), characterized in that the required developed braking torque on the wheels when starting the car from a stop on a hill is controlled by the transmission torque and 039372 resistance to the movement of the car back, while the regulation of the braking torque is carried out by controlling the pressure of compressed air in the brake chamber (8) using a pneumatic modulator (6) of the anti-lock system when using a time-pulse signal with individual parameter settings at each cycle of operation of the electronic control unit of the anti-lock brake systems in real time.