Drive device

The present invention is electronically driven locking device for a locking element of a motor vehicle. The device has a motor, a gear wheel including a gear ring, a hub, and an elastic intermediate element, and a control disk. The motor is linked to the gear ring via a worm gear which is arranged to turn the gear. The control disk is linked to the locking element such that when the gear ring is turned, the hub is turned via the intermediate element which in turn engages the locking element to close or open. The intermediate element is arranged to absorb kinetic energy in the device.

The present application is a continuation of International Application PCT/DE02/01821 filed on 21 May, 2002, which designated the United States and further claims priority to German patent 10125093.2, filed 23 May, 2001, the both of which are herein incorporated by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a drive device with an actuating drive for driving a movable element, in particular a locking device of a motor vehicle door, by means of a gear wheel which has a gear ring and a hub, it being possible for the gear ring to be driven directly or indirectly by the actuating drive and for the movable element to be acted on indirectly or directly by the hub of the gear wheel.

Locking devices of motor vehicle doors are usually driven mechanically or electrically. Electrically driven locking devices are used in particular when a particularly rapid opening and/or locking operation of the motor vehicle door is required. A particularly powerful motor which runs up to particularly high revolutions in a particularly short time is required for a particularly rapid opening and/or locking operation of a motor vehicle door. However, as the opening and/or locking operation takes only a particularly short amount of time, the actuating drive which drives the locking device is usually turned off again, that is to say run down, directly after it has been run up. Even if the actuating drive which activates the locking device is immediately switched off, the kinetic energy of the motor can cause a considerable peak torque to be applied to some elements driven by the motor. This loading can damage components of the drive train and, in extreme cases, even destroy them. However, as an electronically driven locking device of a motor vehicle in a motor vehicle door requires an extremely small amount of space, it is usually not possible to absorb the kinetic energy over a particularly long path when turning off the actuating drive which drives the locking device.

SUMMARY OF THE INVENTION

The present invention is therefore based on an object of specifying a drive device of the abovementioned type, which necessitates a particularly small space requirement and in the case of which the kinetic energy of the actuating drive can be reliably absorbed even if the actuating drive is suddenly switched off.

This and other objects are achieved according to the invention in that the gear ring of the gear wheel and the hub of the gear wheel are composed of predominantly rigid material and are joined to one another by a predominantly elastic intermediate element.

The invention proceeds from the consideration that the kinetic energy of an actuating drive can produce a considerable peak torque which should be absorbed in order to reliably avoid mechanical damage to the drive device. The kinetic energy could be absorbed by allowing the motion of the respectively moving components to die away. However, space is required in the housing of the drive device to allow the motion of the moving components to die away. This space cannot be provided, as the drive device is provided for installation in particularly narrow elements such as a motor vehicle door. It should therefore be possible to allow the motion of the moving components of the motor of the drive device to die away not over a kinetic path but using components which are already present in the drive device. If the actuating drive and the movable element are now decoupled, then the excess kinetic energy can be absorbed by means of the decoupling element. However, it should be reliably ensured here that it is still possible to activate the movable element in a particularly reliable way. Elastic material, which is arranged within the drive device between the actuating drive and the movable element, is suitable as decoupling medium. However, it should be possible here to dispense with an additional element within the drive device. For this purpose, the gear ring of the gear wheel and the hub of the gear wheel are joined to one another by a predominantly elastic intermediate element. After the actuating drive has been turned off, the elastic intermediate element swings back into its initial position and in this way absorbs kinetic energy of the drive device still present in said drive device after the actuating drive has operated.

The gear ring of the gear wheel and the hub of the gear wheel are advantageously joined to one another with a material-to-material bond by the elastic intermediate element. In this configuration, the elastic intermediate element is part of the gear wheel. As a result, the drive device has a particularly small overall size. Furthermore, it is possible to dispense with additional fastening means, as the gear ring and the hub of the gear wheel are joined by the elastic intermediate element, for example by means of the two-component technique. All hard/soft combinations which can be joined to one another with a material-to-material bond are suitable for this purpose.

The predominantly rigid material of the gear ring of the gear wheel and of the hub of the gear wheel is advantageously predominantly rigid plastic, the elastic intermediate element being composed of a predominantly elastic plastic. Plastics can be joined to one another with a material-to-material bond in a particularly easy manner, for example chemically, as a result of which the expenditure on manufacture of the drive device is particularly small.

The hub of the gear wheel advantageously engages in a gear ring of a control disk, the control disk in turn releasing or locking the movable element directly or indirectly. Here, the gear wheel represents the connecting element between the actuating drive and the control disk. Particular requirements made on the loading of the movable element can be allowed for by means of the control disk.

The hub of the gear wheel advantageously has a stop which releases or locks the movable element as a function of the position of the gear wheel. The hub, which is provided with a stop, can act, directly or indirectly, on a movable element, in particular a locking device of a motor vehicle door, as a result of which a drive device, in particular for a locking device of a motor vehicle door, is realized particularly effectively with a particularly small number of elements.

The actuating drive of the drive device is advantageously an electric motor. It can be a commercially available electric motor, as a result of which the financial expenditure of the drive device is particularly small.

The advantages achieved with the invention lie in particular in the fact that the drive device has a particularly small overall height, which recommends it in particular as the drive for a locking device of a motor vehicle door. At the same time, it is possible here to ensure particularly low wear of the drive device, as long as the elastic intermediate element is made from material which withstands loading for a prolonged time.

DETAILED DESCRIPTION OF THE INVENTION

Mutually corresponding parts are provided with the same designations in all figures.

The drive device10according toFIGS. 1 and 2is provided for an electrically operated lock of a door of a motor vehicle. The door and the motor vehicle are not shown in greater detail in the drawing.

The drive device10is arranged in a housing11and comprises an actuating drive12, which is a commercially available electric motor. The actuating drive12can be supplied with electricity externally (not shown in greater detail in the drawing). The actuating drive12has an actuating drive housing14, from which a shaft16protrudes. A worm18is arranged on the shaft16. The shaft16and the worm18according to the drawing are of one-piece design, as an alternative they can also be of two-piece design, however. The worm18meshes a gear wheel20, which has a gear ring22and a hub24.

The hub24of the gear wheel20meshes in turn with a gear ring26of a control disk28. This meshing connection takes place below the gear ring20and can therefore not be seen inFIGS. 1 and 2. The control disk28has a stop29, by means of which it is possible to set a starting and a rest position of the drive device10. Furthermore, the stop29serves for fixing a position of maximum deflection of the drive device10by means of a stop30fixed to the housing.

The gear ring22of the gear wheel20and the hub24of the gear wheel20are composed of predominantly rigid material31, which is plastic in this exemplary embodiment. The gear ring22of the gear wheel20and the hub24of the gear wheel20are joined to one another by an elastic intermediate element32. The elastic intermediate element32is composed of a predominantly elastic plastic33. The gear ring22of the gear wheel20and the hub24of the gear wheel20are joined to one another with a material-to-material bond by what is known as a two-component technique.

A first arm36of a two-armed lever38engages in a depression35, arranged on the upper side34of the control disk28, by means of a lug, which is arranged at the end region of the first arm36of the lever38so as to extend approximately parallel to the rotational axis41of the control disk28(not shown in greater detail in the drawing). The depression35is configured as an approximately circular channel which extends asymmetrically to the rotational axis41of the control disk28at least one location. A lug (not shown in greater detail in the drawing) of a second arm40of the two-armed lever38likewise engages in the underside44of the control disk28. The two arms36and40of the two-armed lever38are prestressed against the control disk28by means of a spiral spring46. The spiral spring46is arranged on a projection48of the housing11. The spiral spring46is of one-piece design, but it can alternatively also be of two-piece design. The two-armed lever38is connected via a shaft50to a first movable element52A and a second movable element52B which is configured as locking elements for a motor vehicle door.

FIG. 3shows the actuating drive12, the gear wheel20and the control disk28from below. It can be clearly seen that the hub24of the gear wheel20and the gear ring26of the gear wheel20are joined to one another by the elastic intermediate element32.FIG. 3also shows how the hub24of the gear wheel20meshes the gear ring26of the control disk28. It is also possible to see the stop29by means of which it is possible to fix a defined position of the drive device10using the stop30which is fixed to the housing. Furthermore,FIG. 3contains a depression54which is provided for a lug of the arm40of the two-armed lever38and designed for a 360 degree rotational movement of the lug. Here, the depression54is delimited by three projections56at the edge58of the control disk28and by an elevation60extending asymmetrically to the rotational axis41of the control disk28. Alternatively, it is also possible to provide more or less than three projections. Furthermore, it is also possible to configure the depression54to be approximately in the shape of a channel.

During the operation of the drive device10, the actuating drive12, configured as an electric motor, is supplied with electricity in a manner not shown in greater detail. The shaft16of the actuating drive12rotates when electricity is supplied. The rotational movement of the shaft16is transmitted to the hub24of the gear wheel20via the worm18and the gear ring22of the gear wheel20. The rotational movement of the actuating drive12is transmitted in turn from the hub24to the control disk28via the gear ring26of the control disk28. The rotational movement of the control disk28in turn moves the two arms36and40of the two-armed lever38as a function of the position of the respective arm36or40in the respective depression35and54, respectively.

If the arm36is situated in the region of the depression35which runs approximately symmetrically to the rotational axis41of the control disk28, then neither the arm36nor the movable elements52A and52B move. If, however, the arm36is situated in the region of the depression35which runs asymmetrically to the rotational axis41of the control disk28, then the arm36of the two-armed lever38is initially deflected in the direction of the rotational axis41and then away from the rotational axis41. This deflection of the arm36of the two-armed lever38causes, via the shaft50, an up and down or to and fro movement of the movable elements52A and52B. In an analogous manner, the movable elements52A and52B are also moved by the second arm40of the two-armed lever38. Here, the two arms36and40of the two-armed lever38can activate the movable elements52A and52B in arbitrary combinations, such as simultaneously, sequentially or individually.

In order for it to be possible for the actuating drive12to run up in a particularly short time and drive the movable elements52A and52B, the actuating drive12is of particularly powerful design. The actuating drive12can displace the movable elements52A and52B in such a way that the stop29of the control disk12comes into contact with the stop30. The situation can therefore arise in which the stop29of the control disk28rests on the stop30fixed to the housing and the actuating drive12continues to be supplied with electricity. The kinetic energy still present in the drive device10on account of the high power of the actuating drive12, both when the stop29of the control disk28reaches the stop30and when the actuating drive12is turned off, is absorbed by the elastic intermediate element32, which will be described in more detail in the following text.

When the actuating drive12is supplied with electricity, the rotational movement of the shaft16is transmitted to the gear ring22of the gear wheel20via the worm18. The hub24of the gear wheel20follows the rotational movement of the gear ring20, as the elastic intermediate element32is of sufficiently rigid configuration. The hub24of the gear wheel20meshes the gear ring26of the control disk28.

After the actuating drive12has been supplied with electricity and the stop29of the control disk28has reached the stop30, the control disk28barely moves any more, as its stop29rests on the stop30fixed to the housing. However, the actuating drive12continues to run and still continues to drive the shaft16, the worm18, arranged on the shaft16of the actuating drive12, and the gear ring22of the gear wheel20in the direction predefined by the actuating drive12, on account of the fact that the actuating drive12continues to run. After the stop29of the control disk28has reached the stop30, this movement of the shaft16of the actuating drive12, is transmitted to the gear ring22of the gear wheel20via the shaft16and the worm18. On account of the elastic properties of the elastic intermediate element32, the elastic intermediate element32now twists without rotating the hub24of the gear ring20with it. Therefore, a first virtual fixed point on the gear ring22of the gear wheel20is displaced relative to a second virtual fixed point on the hub24of the gear wheel20. The extent of the displacement is dependent here on the elasticity of the elastic intermediate element32. Therefore, the second virtual fixed point on the hub24of the gear wheel20lags behind the first virtual fixed point on the gear ring22of the gear wheel20in the direction of rotation. The actuating drive12is of such dimensions that the actuating drive12cannot effect a further rotational movement of the gear wheel20given a maximum deflection of the elastic intermediate element32. Therefore, the twisting of the elastic intermediate element32reliably absorbs excess kinetic energy of the actuating drive12.

Alternatively, the actuating drive12can be turned off by a control device (not shown in greater detail) when the stop29of the control disk28reaches the stop30. The shaft16then comes to rest only after the actuating drive12has been switched off. Once the shaft16is at a standstill, the elastic intermediate element32initially continues to swing in the previous direction. The two virtual fixed points on the gear ring22of the gear wheel20and on the hub24of the gear wheel20are arranged approximately opposite one another until the shaft16comes to a standstill. Once the shaft16is stationary, the first virtual fixed point arranged on the gear ring22of the gear wheel20overtakes, as it were, the second virtual fixed point arranged on the hub24of the gear wheel20. The extent of the deflection of the first virtual fixed point compared with the second virtual fixed point is dependent here on the elastic properties of the elastic intermediate element32.

After a point of maximum deflection, defined by the elastic properties of the elastic intermediate element32, has been reached, the elastic intermediate element32then swings back in the opposite direction and once again changes its swing direction as soon as it has reached a further point of maximum deflection. The elastic intermediate element32swings to and fro here in a damped manner, as no further energy is supplied to the elastic intermediate element32. The elastic intermediate element32swings until it has reached its position of rest. The elastic intermediate element32therefore has the effect of allowing the motion of the control wheel28to die away slowly when the actuating drive12is turned off. As a result, the rotational movement of the control disk28is slowly braked in a damped manner. If the control disk28were not braked, the dying-out of the motion of the control disk28could cause teeth of the control disk28, of the hub24of the gear wheel20and of the gear ring22of the gear wheel20to be destroyed in an undamped manner on account of the kinetic energy of the actuating drive.

The motion of the elastic intermediate element32dies away in a comparable manner if the actuating drive12is turned off without the stop30of the control disk28coming into contact with the stop30.

The elastic intermediate element32, which connects the hub24of the gear wheel20to the gear ring22of the gear wheel20, ensures that, when the actuating drive12is turned off, the excess kinetic energy of the actuating drive12and the associated peak torque are absorbed by the drive device, without components of the drive device being damaged or, in an extreme case, even destroyed in the process. At the same time, the drive device10has a particularly small space requirement which recommends it in particular as the drive of a locking device for a door of a motor vehicle.