Method and device for immobilizing a road vehicle in a stationary state

Abstract

A method for immobilizing a road vehicle in a stationary state by using the compression resistance of its combustion engine (2) is disclosed, characterized in that it comprises the following steps: immobilizing the vehicle by its wheel brakes, shutting down the engine (2), disconnecting the vehicle transmission (1) to uncouple the combustion engine from the wheels, setting the angle of the engine crankshaft (2) to compress at least one cylinder, and closing the vehicle transmission (1).

Description

Technical Field

[0001] This invention relates to the control of a hybrid powertrain and to fixing the hybrid powertrain in a stationary state.

[0002] More specifically, the subject of this invention is a method and apparatus for fixing a road vehicle in a stationary state, using its mass to influence the compression resistance of its combustion engine. Background Technology

[0003] In hybrid vehicles that connect an electric motor to a combustion engine, it may be necessary to use the compression resistance of the combustion engine to keep the vehicle stationary, especially at very low temperatures. In these cases, it is necessary to keep the engine crankshaft mechanically connected to the vehicle's wheels. For this, the transmission must be "closed," engaging the gear ratio.

[0004] With manual transmissions, drivers seek to benefit from the compression resistance of the combustion engine to keep their vehicle stationary, especially on slopes, and to reflexively engage speed after the engine is turned off and the brakes may have been applied.

[0005] If the driver subsequently disengages the brakes, the vehicle tends to lurch forward or backward uncontrollably. This lurching is caused by the distance between two adjacent compression points of the crankshaft. The degree of lurching depends on the deceleration between the engine and the wheels, and also on the radius of the wheels. It allows the vehicle to adjust its position through the compression of the cylinders.

[0006] The vehicle's vibrations can reach tens of centimeters. This distance is determined by the crankshaft's rotation angle between two compressions. It is equivalent to the product of the crankshaft's rotation angle α, the wheel's reduction ratio r, the wheel's radius R, and 2π / 360.

[0007] In short, if the driver chooses to bring the vehicle to a stop by using the engine, engaging the gear ratio, whether it is a combustion engine vehicle or a hybrid vehicle, the vehicle is at risk of a jolt response, thus putting the engine in a compression position when the brakes disengage. Summary of the Invention

[0008] The present invention aims to eliminate any risk of a vehicle reacting when its kinematic chain is closed and the engine is off.

[0009] For this purpose, the present invention proposes to perform the following operations:

[0010] - Use its wheel brakes to secure the vehicle and turn off the engine.

[0011] - Disconnect the vehicle's transmission to disconnect the combustion engine from the wheels.

[0012] - Adjusting the crankshaft angle of the engine when compressing at least one cylinder, and

[0013] - The vehicle's transmission is closed.

[0014] Preferably, during crankshaft adjustment, the assembly consisting of the combustion engine and the first electric motor is not mechanically connected to the vehicle's wheels.

[0015] The proposed device, which uses its mass to influence the compression resistance of its combustion engine to keep a road vehicle stationary, has a first coupling device that can connect or disconnect the components consisting of the engine and electric motor to the transmission so as to allow adjustment of the crankshaft angle.

[0016] The present invention is preferably, but not limited to, vehicles having a hybrid powertrain.

[0017] Before the transmission is closed again, one or more electric machines are used to compress the combustion engine, thus perfectly holding the vehicle stationary. Attached Figure Description

[0018] Other features and advantages of the invention will become apparent from the following description of non-limiting embodiments of the invention and with reference to the accompanying drawings.

[0019] [ Figure 1 [I] is a simplified kinematic diagram of a hybrid power PT.

[0020] [ Figure 2 [A portion of it is shown separately.]

[0021] [ Figure 3A Convert crankshaft adjustments into charts.

[0022] [ Figure 3B The same applies.

[0023] [ Figure 4 The method is shown. Detailed Implementation

[0024] exist Figure 1 The diagram illustrates, in a limited manner, a device for holding a road vehicle stationary by influencing the compression resistance of its combustion engine. This simplified diagram corresponds to the motion structure of a hybrid powertrain (PT), such as the structure described in detail in publication FR 3 022 495, which can be referenced by way of citation.

[0025] The PT consists of a stepped-ratio transmission 1 that combines the torque of the combustion engine 2 and the torque of the electric traction machine 3 in the vehicle wheel direction. The engine 2 and the machine 3 are mounted on concentric main shafts 4 and 5. Their torques are converged on the countershaft 6 of the drive differential 7, which distributes torque between the two wheels of one axle. The combustion engine 2 is connected to another electric motor 8, such as a starter or supplementary machine, via a set of reduction gears 9a, 9b, and 9c.

[0026] The proposed fixing device has the following features:

[0027] - First coupling device C3, which is capable of connecting or disconnecting the components consisting of the engine and electric motor 8 to the transmission so as to enable adjustment of the crankshaft angle;

[0028] - A second connecting device C2, which connects the electric traction machine 3 to the transmission to change the position of the transmission shaft when the crankshaft angle is adjusted; and - a third connecting device C1, which connects the engine 2 directly to the traction machine 3.

[0029] The combined closure of the two connecting devices C3 and C2 ensures the engagement of the transmission ratio, at which the combustion engine is connected to the wheels. At this transmission ratio, the electric traction machine 3 is also connected to the wheels.

[0030] The transmission 1 can transmit the compression resistance of the combustion engine 2 to the wheels when stationary, so that when the vehicle's brakes are disengaged, the vehicle can be secured using two couplings C3 and C2. The combined closure of these two couplings can close the transmission and fix the vehicle in a stationary state by engaging the gear ratio (at which the combustion engine 2 is connected to the wheels, and the electric traction machine 3 is also connected to the wheels).

[0031] In this state, the transmission can limit or even completely eliminate the slight displacement of the vehicle caused by its bumps, displacement that would normally inevitably affect the compression of the cylinders of combustion engine 2 once the vehicle stops and its engine is shut off. This result is achieved by the action of electric motor 8 or 3 on the combustion engine. This action involves actuating electric motor 8 or 3 to adjust the crankshaft angle at the compression position of engine 2, while the vehicle remains stationary via its wheel brakes, wherein the engine shuts off when its transmission is disengaged and then the transmission is re-engaged.

[0032] In the first embodiment, the crankshaft angle is adjusted by an electric motor 8, which is connected via reduction gear sets 9a, 9b, and 9c. Alternatively, a belt or any other transmission device can be used to ensure that the movement of the electric motor 8 is reduced in speed relative to the combustion engine 2.

[0033] Machine 8 is an electric motor that can be controlled in terms of force and / or position, such as a starter or a simple supplementary machine. During crankshaft adjustment by machine 8, the assembly consisting of combustion engine 2 and machine 8 (in...) Figure 2 (Shown separately) It is not mechanically connected to the vehicle wheels because all the couplings of the transmission are disconnected.

[0034] The vehicle is secured in a stationary state as follows: The driver applies the brakes until the vehicle comes to a standstill. Then, at the driver's request, the combustion engine 2 is shut off. The engine is disconnected from the wheels by disconnecting couplings C3 and C2. The combustion engine 2 and the first electric motor 8 are then separated from the wheels.

[0035] Initially, the angular position of the crankshaft was random, such as Figure 3A As shown. Then, the combustion engine 2 is rotated by the electric motor 8 to adjust the crankshaft during cylinder compression. This movement continues until reaching... Figure 3B The position shown. From this point on, electric motor 8 holds the crankshaft in place.

[0036] The following operations involve the vehicle's transmission 1. By closing... Figure 4 Connectors C3 and C2 are used to engage the gear ratio, such as the first forward gear ratio. Closing them allows the movement of the combustion engine 2 and the electric motor 8 to be reduced in the wheel direction across the differential 7. Then, the combustion engine 2 is connected to the wheels via the first combustion engine ratio, and the mass of the vehicle affects the compression of the cylinders.

[0037] In summary, the method for fixing a vehicle in a stationary state, by using its mass to influence the compressive resistance of the combustion engine, mainly includes the following steps:

[0038] -Use its wheel brakes to secure the vehicle.

[0039] -Shut down engine 2

[0040] - Disconnect the vehicle's transmission 1 to disconnect the engine 2 from the wheels.

[0041] - Adjust the crankshaft angle of engine 2 when compressing at least one cylinder, and

[0042] - Close the vehicle's transmission 1.

[0043] In one variant, the crankshaft position can be slightly altered by the electric traction mechanism 3 and the inner shaft of the housing. The position of the inner shaft is then controlled by the electric traction mechanism 3. The above method still applies.

[0044] The transmission described in the accompanying drawings does not limit the application of the proposed method to any specific hybrid powertrain configuration. The method can be implemented in any type of transmission train (PT) having a combustion engine, a transmission capable of temporarily disconnecting the engine from the wheels, and an electric motor engaged with the engine's crankshaft. Its main advantage is the ability to control the vehicle's displacement while bringing it to a standstill by "influencing" the engine's compression.

[0045] In the described example, the engaged transmission ratio is based on Figure 4 The first forward gear ratio is engaged by closing the couplings C3 and C2 of the transmission. However, without departing from the scope of the invention, the method can be applied by engaging another forward or reverse gear ratio, depending on the vehicle's orientation relative to the slope.

Claims

1. A method for fixing a road vehicle in a stationary state by influencing the compressive resistance of its combustion engine (2), characterized in that, The method comprises the following steps: -Use its wheel brakes to secure the vehicle. -Shut down the engine (2), - Disconnect the vehicle's transmission (1) to disconnect the engine (2) from the wheels. - Adjust the angle of the crankshaft of the engine (2) while compressing at least one cylinder, and - Close the vehicle's transmission (1).

2. The method as described in claim 1, characterized in that, The angle of the crankshaft is adjusted by an electric motor connected to it.

3. The method as described in claim 2, characterized in that, During the adjustment of the crankshaft angle, the assembly consisting of the combustion engine and the electric motor is not mechanically connected to the vehicle's wheels.

4. The method as described in claim 2 or 3, characterized in that, The electric machine can be controlled in terms of force and / or position.

5. The method as described in claim 1, characterized in that, The angle of the crankshaft is adjusted by the inner shaft of the transmission (1).

6. The method as described in claim 5, characterized in that, The angle of the crankshaft to the inner shaft of the transmission is adjusted by an electric traction machine.

7. An apparatus for fixing a road vehicle in a stationary state by influencing the compression resistance of its combustion engine (2) by means of the method as described in any one of claims 2 to 5, characterized in that, The device has a first coupling device (C3) that connects the components consisting of the engine and the electric motor to the transmission so that the crankshaft angle can be adjusted.

8. The apparatus as claimed in claim 7, characterized in that, The device has a second coupling device (C2) that enables the electric traction machine to be connected to the transmission to change the position of the transmission shaft when the crankshaft angle is adjusted.

9. The apparatus as claimed in claim 8, characterized in that, The combined closure of the first coupling device (C3) and the second coupling device (C2) ensures the engagement of the transmission ratio, with which the combustion engine is connected to the wheels.

10. The apparatus as claimed in claim 9, characterized in that, With this gear ratio, the electric traction machine is also connected to the wheels.

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