Method for braking a vehicle

Patent metadata

Field	Value
Publication number	US-9327719-B2
Application number	US-201314410604-A
Country	US
Kind code	B2
Filing date	Jun 26, 2013
Priority date	Jun 27, 2012
Publication date	May 3, 2016
Grant date	May 3, 2016

Abstract

A method for braking a vehicle driving forward towards stop. The vehicle has a propulsion system including a combustion engine with an output shaft ( 2 a ), a gearbox ( 3 ) with an input shaft ( 3 a ), an electric machine ( 9 ) comprising a stator and a rotor, and a planetary gear comprising a sun gear ( 10 ), a ring gear ( 11 ) and a planet wheel carrier ( 12 ). When braking the vehicle, a reverse gear of the gearbox is engaged and the electric machine is controlled to apply brake torque requested to the input shaft of the gearbox.

First claim

The invention claimed is:

1. A method for braking a vehicle driving forward towards stop, wherein the vehicle comprises:
a propulsion system comprising a combustion engine with an output shaft, a gearbox with an input shaft, an electric machine comprising a stator and a rotor, and a planetary gear comprising three components in the form of a sun gear, a ring gear and a planet wheel carrier;
the output shaft of the combustion engine is connected to a first of the components of the planetary gear so that rotation of the output shaft causes rotation of the first component;
the input shaft of the gearbox is connected to a second of the components of the planetary gear so that rotation of the input shaft causes rotation of the second component, and the rotor of the electric machine is connected to a third of the components of the planetary gear so that rotation of the rotor causes rotation of the third component;
the propulsion system further comprising locking means movable between a locking position in which two of the components are interlocked, so that the three components rotate with the same rotational speed, and a releasing position, in which the components are allowed to rotate with different rotational speeds;
the method comprises the steps of:

a) controlling the electric machine and/or the combustion engine for providing a state of zero torque between the two of the components which are interlocked by the locking means,
b) moving the locking means to the releasing position,
c) controlling the electric machine and/or the combustion engine so that through the input shaft of the gearbox, they create a state of zero torque in the gearbox,
d) then disengaging the gear presently engaged in the gearbox,
e) controlling the electric machine and/or the combustion engine so that the rotational speed of the third component together with the rotational speed of the output shaft of the combustion engine gives the input shaft of the gearbox a rotational speed which for the existing speed of the vehicle is synchronized with the shaft rotational speed for a reverse gear of the gearbox,
f) engaging the reverse gear of the gearbox,
g) checking brake torque requested of the propulsion system, and
h) controlling the electric machine to apply the brake torque requested through the third component to the input shaft of the gearbox,
and optionally, omitting the steps a) and b) if the locking means is in the releasing position at the start of the method.

2. A method according to claim 1 , wherein the vehicle has the propulsion system with the sun gear as the first component and the ring gear as the third component that is braked.

3. A method according to claim 1 , performed for a vehicle having a propulsion system comprising a range gear.

4. A method according to claim 3 , further comprising before performing the method, ensuring that a high range gear is engaged.

5. A method according to claim 1 , further comprising performing step g) repeatedly or continuously while performing step h), and controlling the rotational speed of the output shaft of the combustion engine towards a predetermined rotational speed of the combustion engine as long as the checking indicates that brake torque is requested.

6. A method according to claim 5 , further comprising controlling the output shaft of the combustion engine towards a predetermined rotational speed in the form of a low rotational speed of the combustion engine.

7. A method according to claim 1 , further comprising performing step g) repeatedly or continuously while performing step h), and as long as the checking indicates that brake torque is requested, controlling the combustion engine to deliver a rotational speed of the output shaft thereof which is dependent on the rotational speed of the rotor of the electric machine such that the electric machine is during performance of step h) controllable to brake the input shaft of the gearbox while generating a maximum electric regenerative power.

8. A method according to claim 1 , further comprising stopping fuel injection in the combustion engine while performing step h) and when the output shaft of the combustion engine has substantially, stopped, locking the output shaft against rotation, and continuing step h) with the combustion engine turned off.

9. A method according to claim 1 , further comprising checking that steps g) and h) are performed when the checking shows that instead of a brake, torque an acceleration torque of the propulsion system is requested and the acceleration torque, is less than the product of the torque needed for driving the combustion engine to rotate and the transmission ratio of the planetary gear; and
controlling the electric machine to reverse the direction of the torque applied to the input shaft of the gearbox through the third component so as to apply the acceleration torque requested to the input shaft.

10. A method according to claim 1 , further comprising checking that steps g) and h) are performed, and that when the checking shows that instead of a brake torque, an acceleration torque of the propulsion system is requested and the acceleration torque is less than the product of the torque needed for driving the combustion engine to rotate and the transmission ratio of the planetary gear, controlling the electric machine or controlling the electric machine and the combustion engine so that through the input shaft of the gearbox it/they provide a state of zero torque in the gearbox, whereupon disengaging the reverse gear, controlling the electric machine and/or combustion engine so that the rotational speed of the third component together with the rotational speed of the output shaft of the combustion engine give the input shaft of the gearbox a rotational speed which, for the existing speed of the vehicle, is synchronized with the shaft rotational speed for a forward gear of the gearbox and then engaging the forward gear of the gearbox.

11. A method according to claim 1 , further comprising checking that steps g) and h) are being performed, and when the checking shows that instead of a brake torque, an acceleration torque of the propulsion system is requested and the acceleration torque is larger than the product of the torque needed for driving the combustion engine to rotate and the transmission ratio of the planetary gear, controlling the electric machine or controlling the electric machine and the combustion engine so that it/they through the input shaft of the gearbox gives/give a state of zero torque in the gearbox, whereupon disengaging the reverse gear, the electric machine and/or the combustion engine is/are controlled so that the rotational speed of the third component together with the rotational speed of the output shaft of the combustion engine give the input shaft of the gearbox a rotational speed which for the existing speed of the vehicle is synchronized with the shaft rotational speed for a forward gear of the gearbox and the forward gear of the gearbox is then engaged.

12. A method according to claim 1 , further comprising the step a) comprises calculating the rotational speed by which the input shaft of the gearbox is to be driven for producing a state of zero torque between the components interlocked by the locking means for the existing speed of the vehicle and the gear engaged in the gearbox;
and also comprises calculating of the rotational speeds of the output shaft of the combustion engine and the rotor of the electric machine required for obtaining the state of zero torque.

13. A method according to claim 1 , further comprising the step c) comprises calculating the rotatio

Assignees

• Scania Cv Ab

Inventors

• Pettersson Niklas
• Bergquist Mikael
• Lindström Johan
• Kjell Anders
• Björkman Mathias

Classifications

• Y02T10/7077

  Cross-Sectional Technologies · mapped topic

• B60W10/11

  Stepped gearings · CPC title

• B60L11/14

  Operations & Transport · mapped topic

• Y10T477/24

  Cross-Sectional Technologies · mapped topic

• B60W10/06

  including control of combustion engines · CPC title