Spindle drive

Abstract

The invention relates to a spindle drive (10) for use in a closure element of a motor vehicle. The spindle drive (10) has a drive motor (20) which is designed as a DC motor and wherein the spindle drive (10) has a control unit which is designed to control the drive motor (20). Characterized in that the spindle drive (10) is designed to detect an actuating force acting on the drive motor (20) via the closure element, and in that the control unit is designed to control the drive motor (20) as a function of the detected actuating force.

Description

Technical field

[0001] The present invention relates to a spindle drive for a closure element, in particular for a motor vehicle. Furthermore, the invention relates to a motor vehicle. State of the art

[0002] Spindle drives can be used to convert the rotary motion of a motor into the translational motion of a spindle and / or an associated component, such as a sleeve. The spindle drive can thus be used as an actuator. The spindle drive can be used as a drive device for opening or closing flaps or doors. Typical applications in motor vehicles are motor-adjustable tailgates, trunk lids, or side doors. The spindle drive replaces, for example, a tailgate damper in manually adjustable tailgates without motor assistance. Such a tailgate damper can be designed as a gas pressure spring, for example.

[0003] DE 10 2016 209 986 A1 describes a method for operating an electric motor-driven adjustment drive, for example, an electric motor-driven tailgate. The electric motor used can be a brushless DC motor or, alternatively, a brushed DC motor with position sensors, such as Hall sensors. To control the adjustment drive, a characteristic variable of the electric motor-driven adjustment drive is detected, for example, using sensors of the motor vehicle or using sensors external to the vehicle, and a parameter data set is created from this. A control unit for controlling the adjustment drive is designed separately from the adjustment drive. Overall, integrating the adjustment drive into the motor vehicle is complex and laborious. Description of the invention

[0004] A first aspect of the present invention relates to a spindle drive for a closure element, for example a flap, in particular for a motor vehicle. The closure element can be adjustable between an open position, in which an access opening to the motor vehicle is at least partially exposed, and a closed position, in which the access opening is blocked. The spindle drive can be designed to adjust the closure element, for example by pivoting the closure element between these two positions. The closure element can be designed, for example, as a tailgate, engine hood, fuel tank or loading lid, or door. The closure element can, for example, be rotatably mounted on one side of a body of the motor vehicle. The spindle drive can be mounted at a distance from the mounting of the closure element, with one end on the body and an opposite end on the closure element.The spindle drive can be designed to convert a rotational movement, for example of a motor shaft, into a translational movement. The spindle drive can be designed to change its length, for example by retracting and extending a spindle or a component connected to it. The spindle can form one end of the spindle drive and be mounted for axial movement. However, a rod or sleeve can also be connected to the spindle and is extended from a housing of the spindle drive. The spindle can also be axially fixed and mounted for only rotational movement. The connected component can then be moved axially along the spindle by rotation of the spindle. In this way, a thread of the spindle can be concealed. The spindle or the connected and axially movable component can form a second end of the spindle drive. The spindle can, for example, be designed as a metallic rod with an external thread.The spindle drive can be so small that it does not exceed the installation space of commercially available gas springs and can, for example, be retrofitted or installed as a spare part in a motor vehicle. The spindle drive can be connected to the vehicle's electrical system for a power supply. The spindle drive can have a brake for the spindle and / or a drive motor. The spindle drive can be self-locking, whereby the locking element can be easily held in position even when the drive motor is not powered. The self-locking can arise due to the mechanical properties or additionally through an electrical motor brake function, which can preferably be activated automatically. The spindle drive can have spring assistance. The spindle drive can have a slip or locking clutch to protect against overload and / or as protection against destruction.

[0005] The spindle drive has a drive motor, which is preferably designed as a direct current motor (DC brushed or BLDC brushless), with particular reference to a brushless DC motor. The drive motor can be designed to move the spindle, in particular to rotate it about its longitudinal axis. For this purpose, a motor shaft of the drive motor can be operatively connected to the spindle or can be operatively connected. For example, the motor shaft can be permanently connected to the spindle in a rotationally fixed manner. A brushless DC motor can also be referred to as a BLDC motor. A brushless DC motor, for example, controlled by integrated control electronics in the housing of a spindle drive, converts a direct current into a suitable three-phase current for operation as a three-phase synchronous machine, with excitation provided by permanent magnets.By controlling the circuit, a moving magnetic field can be generated, which pulls the permanently excited rotor along. For this purpose, the stator coils are preferably electronically commutated. The brushless DC motor can form a very precise servo motor. Furthermore, sparking and the generation of irregular fields, which could affect other electronics and especially the sensor, occur only to a minimal extent, if at all. The electromagnetic compatibility of a brushless DC motor (BLDC) can be particularly high. For example, a brushless DC motor generates significantly less interference than a brushed motor, which means that cell phone reception and radio reception in the surrounding area are less disrupted during operation. A brushless DC motor can also easily provide additional functions.For example, a brushless DC motor can measure its own rotational speed during operation using its own magnetic field. This enables precise speed control. Furthermore, a brushless DC motor, especially a sensor-commutated brushless DC motor, can achieve very high efficiency. Commutation, for example, for motor control and magnetic field control for driving and braking the drive motor, can also be very precise.

[0006] The spindle drive can have an integrated control unit that independently implements programmed functions as soon as the signals from the integrated sensors are detected. Alternatively, the BLDC motor can be electronically commutated.

[0007] The spindle drive has a control unit. The control unit is designed to control the drive motor. For example, the control unit can commutate the drive motor. The control unit can control a power supply for individual phases of the drive motor. The control unit can include the drive motor's control electronics. The control unit can be designed as a microcomputer. The control unit can include a programmable microprocessor. The control unit can provide various functions for controlling the adjustment movement of the closure element independently of the motor vehicle. The control unit can also be called an "electronic control unit" or "electronic control unit." The spindle drive can thus be particularly easily integrated into the motor vehicle.For example, a motor vehicle's microcomputer, microprocessor, or ECU (electronic control unit) does not need to be configured to control a brushless DC motor. Typically, a motor vehicle's ECU is designed only to control brushed motors. The control unit can be programmable, particularly modularly programmable. The control unit can have a permanent memory for the respective control method of the spindle drive.

[0008] Furthermore, a strain gauge or pressure sensor can be integrated into the spindle or actuator to better detect and interpret force effects. Strain gauges are, for example, measuring devices for detecting expanding and / or compressive deformations, preferably for measuring ranges below one millimeter. They change their electrical resistance even with small deformations and are attached to components, for example, using special adhesive. Additionally or optionally, temperature sensors can also be attached next to the strain gauge to account for temperature-related fluctuations that can be caused by environmental conditions or changes in the thermal and cold expansion of the material or the environment. The control unit or ECU can be located in a housing of the spindle drive. This allows the spindle drive to be easily installed on the vehicle as a single assembly.For example, there is no need for separate attachment and integration of the control unit. In addition, the housing can protect the control unit from environmental influences. This means that the control unit can also be arranged in inherently exposed positions, for example on a tailgate or in an environment exposed to the weather. The housing can be designed as a metallic housing or a plastic housing. The housing can, for example, partially or completely accommodate the drive motor. The spindle can also be partially or completely accommodated in the housing. Other components, such as the clutch or the brake, can also be partially or completely arranged in the housing. The housing can delimit an interior spindle space. The housing can be designed as an elongated cylindrical component.For example, only one end of the spindle or an axially movable component connected to it, as well as a cable harness for supplying power to the drive, may protrude from the housing.

[0009] In a further embodiment of the spindle drive, it can be provided that the control unit is integrated into the drive motor. This allows the drive motor and the control unit to be installed as a single component in the spindle drive. For example, the drive motor can have a housing in which the control unit is located. Electronic components of the control unit can also be distributed throughout the drive motor. The control unit can be particularly well protected by being integrated into the drive motor. This also allows the spindle drive to be particularly compact. Furthermore, cables between the control unit and the drive motor within the housing of the spindle drive can be unnecessary. This means that the control unit and the drive motor can also be easily retrofitted in conventional spindle drives, for example with a brush motor. Furthermore, the spindle drive can be particularly easy to integrate into the motor vehicle.For example, the drive motor can simply be connected to the vehicle's electrical system and no further connections may be necessary.

[0010] According to the invention, it is provided that the spindle drive is designed to detect an actuating force acting on the drive motor via the closure element. The actuating force can be applied by a user, who, for example, pulls on the closure element or pushes on the closure element. This force can, for example, induce a voltage and / or a current in the drive motor, for example in motor coils of the drive motor. The actuating force can, for example, also be caused by a stationary obstacle against which the closure element presses during an adjustment movement. In addition, the drive motor can also detect its speed and thus infer an actuating force. The actuating force can be detected while the drive motor is operating and / or when the drive motor is at a standstill. The control unit can also contribute to detecting the actuating force.For example, the control unit can evaluate the current flow and / or voltage at the respective phases of the electric motor to determine the actuation force. Optionally, the speed of the drive motor can also be taken into account.

[0011] The control unit is designed to control the drive motor depending on the detected actuation force. This allows additional locking element functions to be provided. For example, when adjusting the locking element, if the user pulls on the tailgate, it can cause it to adjust more quickly. To do this, the drive motor is supplied with more current. In addition, a slip clutch or other clutch for overload protection can be dispensed with. If the load is too high, for example, the current supplied to the drive motor can be reduced or an adjustment movement can even be reversed in order to protect the drive motor and / or other mechanical components from damage. The drive motor can also act as a brake, which, for example, maintains or supports a fixed position in the event of a blocking current.

[0012] An actuating force curve can also be recorded. The control unit can then be configured to control the drive motor depending on the recorded actuating force curve. Sensors can also be provided in the spindle for this purpose. This allows a first and / or second derivative of the actuating force to be taken into account when controlling the adjustment movement.

[0013] In a further embodiment of the spindle drive, the drive motor can be provided with Hall sensors in the spindle for detecting the speed and / or position of a rotor of the drive motor. With additional detection of the motor current, an actuating force can be determined particularly easily and / or precisely without the need for external force sensors, such as anti-pinch sensors for anti-pinch protection. In addition, the Hall sensors can simplify commutation of the drive motor. The Hall sensors transmit their sensor data, for example, to the control unit. The Hall sensors can be arranged in the housing of the drive motor. Alternatively, the drive motor can also be designed as a sensorless drive motor by measuring the induced voltages in the non-energized motor phases and, in particular, determining the zero crossings of the induced voltages.

[0014] The drive motor can be configured to use a voltage induced in the motor coils of the drive motor to detect the actuating force. For example, the voltage induced in the motor coils can be generated by an actuating force acting on the drive motor via the closure element. For example, a user can manually displace the closure element or at least apply a force to it, thus causing the induced voltage. The drive motor can be configured to detect the actuating force as a function of the voltage induced in the motor coils.

[0015] In a further embodiment of the spindle drive, the control unit can be configured to control the drive motor as a function of the detected actuating force in order to provide at least one closure element function. The closure element function can be a control of the drive motor that goes beyond simply moving the closure element between its two positions. For example, this can enable at least partial manual control of the motorized adjustment of the closure element by manipulating the closure element by a user.

[0016] An example of such a closure element function is a closure element opening in response to a pressure against the closure element, for example when the closure element is in its closed position.

[0017] This allows a user to open the locking element without pulling on a handle. For example, a user can simply press their hip against the tailgate to easily open it when their hands are full. Alternatively or in addition to moving into the open position, the locking element opening can also include an unlocking function. For example, a lock on the locking element can have a degree of play that allows slight movement beyond the closed position in a direction opposite to an adjustment direction into the open position. The actuation and the associated force can thus be detected. For example, the locking element opening can cause a complete or partial adjustment movement into the open position.For example, in response to pulling on the closure element in its closed position, the closure element can be adjusted fully to the open position and, in response to pushing, only to a half-open position between the open position and the closed position.

[0018] Another example of such a closure element function is motor-assisted movement of the closure element. For example, the user can move the closure element manually between its positions. The actuating force applied can be recorded, and the user can thus be assisted by a motor force from the spindle drive. An assisting force can be fixed or proportional to the recorded actuating force. For example, motor assistance is activated if the actuating force is greater than a threshold value. Alternatively or additionally, a speed of the adjustment movement can also be taken into account. The assisting force can be controlled so that the actuating force remains smaller than a further threshold value.For example, the operating force required to open the tailgate can be essentially the same as with an unloaded tailgate, even when there is a snow load on the tailgate. Furthermore, the user can manually specify the opening angle of the tailgate despite the motorized assistance. This allows the tailgate to be motorized, even if a bike rack is in the way, and can therefore be easily moved with the bike rack until it reaches a stop.

[0019] The motor-assisted movement of the locking element can occur by pulling and / or pushing against the locking element. For example, the detected actuation force may have a different sign when pulling than when pushing. In general, when detecting the actuation force, a distinction can be made between a force direction toward a closed position and a force direction toward an open position.

[0020] Another example of such a locking element function is a manual stopping of the locking element during a motorized adjustment of the locking element. In response to the detected actuating force, for example, a motorized adjustment of the locking element can be interrupted and / or an adjustment direction can be reversed. This can occur, for example, if the detected actuating force is opposite to the current adjustment direction and greater than the motorized adjustment force. The user can then manually interrupt the adjustment by directly intervening on the locking element. For example, the user can press against the currently opening tailgate to interrupt the opening process and, optionally, close the tailgate again.

[0021] Another example of such a locking element function is the detection of contact with an obstacle during a motorized adjustment of the locking element. This detection can occur, for example, if the detected actuation force is greater than a threshold value and / or the locking element does not move further despite a high drive force. Contact can be detected if such a condition exists for a minimum period of time. The adjustment process can then be interrupted. For example, the obstacle can be a wall behind the tailgate. Damage to the tailgate in the event of a collision and also to the spindle drive can thus be prevented or at least reduced.

[0022] Thanks to the control unit and the use of the brushless DC motor (BLDC), these locking element functions can be provided integrally with the spindle drive. For example, these functions do not require the use of vehicle sensors and / or a vehicle control unit. This allows the respective functions to be implemented during the production of the spindle drive and easily used on all possible vehicles without the need to adapt the vehicle architecture to the spindle drive. For example, the vehicle's ECU does not need to be configured to commutate a brushless DC motor. All functions could also be implemented in a DC motor with integrated Hall sensors.This means that the drive unit can even retain the original version of the main vehicle, since only the sensor architecture on the drive motor would have to be implemented accordingly.

[0023] In a further embodiment of the spindle drive, it can be provided that the control unit is designed to receive a sensor signal from a vehicle sensor and to control at least one of the closure element functions depending on the sensor signal. For example, the control unit can have a radio interface or a wired interface via which the sensor signal can be transmitted to the control unit. The sensor signal can, for example, be transmitted directly from the vehicle sensor or from the vehicle ECU to the control unit. The vehicle sensor can, for example, be designed as a distance sensor on the closure element. The distance sensor can be a distance sensor which outputs a distance to an obstacle as a sensor signal when the motor vehicle is parked. The vehicle sensor can, for example, be designed as an ultrasonic sensor or radar sensor.The vehicle sensor can also be designed as an optical sensor, such as a laser distance sensor or a camera. The sensor signal can, for example, indicate a detected distance of an obstacle in a movement path of the closure element. The distance sensor can also be designed to detect the distance by determining a field change, for example, a UWB field. The sensor signal can be used to verify the respective detected actuation forces. Alternatively or additionally, further closure element functions can also be implemented depending on the sensor signal. For example, if there is no change in the actuation force curve in relation to a normal actuation force curve and a specific sensor signal, it can be concluded that there is an impending collision (contactless obstacle detection) with an obstacle.The normal actuation force curve can, for example, be an expected actuation force curve within a bandwidth that corresponds to moving the locking element without colliding with an obstacle or being subjected to an external force by a user. The control unit can then stop an adjustment movement of the locking element if an impending collision occurs. This way, opening or closing of the locking element can be interrupted before contact with an obstacle occurs and / or before a minimum distance to the obstacle is exceeded. The user can then cancel this stop, for example, by pressing or pulling the locking element firmly enough, which can be detected accordingly based on the actuation force curve. These signal generators can also be installed hidden behind metal sheets or plastic panels so as not to disrupt the overall design.Hidden areas outside of the field of vision are also possible connection areas.

[0024] In a further embodiment of the spindle drive, it can be provided that the control unit is designed to deactivate at least one of the closure element functions depending on a shutdown signal from a vehicle control unit. For this purpose, the control unit can be designed for connection to the ECU of the motor vehicle, for example via a data bus. The vehicle control unit can be designed as the ECU of the motor vehicle. The shutdown signal can be a simple data signal, which is not inherently suitable for controlling the drive motor. This allows certain functions of the spindle drive to be easily integrated into the vehicle control system. For example, certain functions can be configured via a central control system of the motor vehicle. Furthermore, certain functions whose execution is undesirable in certain vehicle states can simply be switched off.For example, a car wash mode can be set centrally, in which an automatic windscreen wiper is deactivated as well as all automatic locking elements by the spindle drive, which react to an actuating force.

[0025] In a further embodiment of the spindle drive, the control unit can be configured to prevent the closure element from being adjusted by the drive motor during vehicle movement. For this purpose, the control unit can be configured for connection to the ECU of the motor vehicle, for example via a data bus. The control unit can thus receive a current driving speed from the motor vehicle. If this vehicle speed is greater than a threshold value, the adjustment can be prevented. Alternatively or additionally, it can be taken into account whether a handbrake is applied and / or a traction motor of the motor vehicle is activated.The control unit can prevent this adjustment, for example, by shutting off the drive motor, blocking the drive motor, activating a spindle drive brake, or energizing the drive motor so that the locking element is held in position. This reliably prevents unwanted adjustment of the locking element while the vehicle is moving and / or stationary.

[0026] A second aspect relates to a motor vehicle. The motor vehicle has a closure element, for example, designed as a tailgate. The motor vehicle has a spindle drive according to the first aspect. The closure element is adjustable between an open position and a closed position by means of the spindle drive. Respective advantages and further features can be found in the description of the first aspect, wherein embodiments of the first aspect also form embodiments of the second aspect, and vice versa. Short description of the characters

[0027] Fig. 1 illustrates a spindle drive in a schematic sectional view. Fig. 2 illustrates details of the spindle drive in a schematic sectional view according to Fig. 1 . Detailed description of embodiments

[0028] Fig. 1 and Fig. 2illustrate, in a sectional view, a spring-assisted spindle drive 10 for a closure element of a motor vehicle designed as a tailgate. The spindle drive 10 has a housing 12, which forms a bearing 14 for rotatable attachment to a body of the motor vehicle at one end of a longitudinal extent of the spindle drive 10. At an opposite end of the longitudinal extent of the spindle drive 10, a sleeve 16 is arranged, which forms a bearing 18 for a preferably rotatable attachment to the tailgate. The sleeve 16 is partially arranged in the housing 12 and closes the housing 12 at one end. The sleeve 16 forms a rod which can be extended and retracted from the housing 12 by the spindle drive 10. This changes the length of the spindle drive 10. The spindle drive 10 can thus pivot the tailgate between an open position and a closed position.When fully retracted, the tailgate is closed.

[0029] For this adjustment, the spindle drive 10 has a drive motor 20 designed as a brushless DC motor. The drive motor 20 is arranged in the housing 12 at the end facing the bearing 14. The drive motor 20 can be connected to the vehicle's electrical system via a cable harness 22 to supply power to the vehicle. Furthermore, control signals can optionally be transmitted to the spindle drive via the cable harness 22, although these control signals do not directly commutate the drive motor 20. The cable harness 22 protrudes from the housing 12 at the end facing the bearing 14. The drive motor 20 has a motor shaft 24. The motor shaft 24 is mechanically connected to a spindle 32 via a freewheel clutch 26, which functions as a brake, a gear 28, and a clutch 30, which here is designed, for example, as a slip clutch. The spindle 32 is rotatably mounted in the housing 12.

[0030] A nut 34 with its internal thread is mounted axially displaceably on an external thread of the spindle 32. The nut 34 is fixed to the sleeve 16 in a rotationally fixed manner. Rotation of the spindle 32 causes the nut 34 to be axially displaced along the spindle 32. Accordingly, the sleeve 16 is extended or retracted, thus axially changing the length of the spindle drive 10. This causes the tailgate to be opened or folded by the motor.

[0031] The spindle drive 10 has a control unit. The control unit is designed to control the drive motor 20. The control unit is integrated into the drive motor 20 and thus arranged in the housing 12 of the spindle drive 10. The control unit regulates the commutation of the respective phases of the drive motor 20. In addition, the control unit also detects a rotational speed of the drive motor 20, for example via Hall sensors of the drive motor 20, and respective variables induced by external actuating forces. The spindle drive 10 is thus designed to detect an actuating force acting on the drive motor 20 via the closure element. The control unit is also designed to control the drive motor 20 depending on the detected actuating force.Thus, purely by means of the spindle drive 10, without recourse to vehicle sensors and without calculation or direct motor control by a motor vehicle ECU, further locking element functions can be provided, which can be programmed accordingly. An example of such a locking element function is actuation force-dependent control of an adjusting force for the locking element. The spindle drive 10 can thus be installed on the motor vehicle as a single assembly. Additional integration of the control unit at a separate location to a lifting cylinder for the tailgate formed by the spindle drive 10 is not necessary. Integration of respective functions into a vehicle control system and configuration of the motor vehicle ECU for controlling and, in particular, commutation of a brushless DC motor or even a brushed DC motor are thus also not necessary.

[0032] In a further embodiment of the spindle drive, the control unit can be configured to drive the closure element using the drive motor, which can also be a conventional DC motor (brushed direct current motor), to perform the same functions as described above. The prerequisite would be the corresponding sensor functions (Hall sensors) as previously mentioned.

[0033] An electronic shutdown device can be provided which switches off, for example, within about 0.5 seconds (depending on the requirements of the DC motor manufacturer) if the block current is too high in order to protect the PCBA of the DC motor from overheating.

[0034] In contrast to pure overheating protection, the advantage is that, while with overheating protection the entire CSD system is shut down and reset (usually by manually closing the tailgate and restarting the ignition), all systems now remain active after excessively long or excessive blocking current to the DC motor. This means that the system enters "braked pause mode" and does not shut down completely by default to prevent motor overheating. To prevent overheating, the DC motor is no longer powered, but the motor phases are short-circuited, for example.

[0035] For example, this function could be activated after an overcurrent lasting 0.2 seconds, while the protection device would only be activated after 0.5 seconds if the spindle drive fails to respond, to protect the entire system or the DC motor. The DC motor can be brushless (BLDC) or brushed. List of reference symbols

[0036] 10Spindle drive 12Housing 14Bearing 16Sleeve 18Bearing 20Drive motor 22Cable harness 24Motor shaft 26Overrunning clutch 28Gearbox 30Coupling 32Spindle 34Nut

Claims

1. Spindle drive (10) for use in a closure element of a motor vehicle, wherein the spindle drive (10) has a drive motor (20) which is designed as a DC motor, and wherein the spindle drive (10) has a control unit which is designed to control the drive motor (20), characterized in that the spindle drive (10) is designed to detect an actuating force acting on the drive motor (20) via the closure element, and that the control unit is designed to control the drive motor (20) as a function of the detected actuating force.

2. Spindle drive (10) according to claim 1, characterized in that the control unit is arranged in a housing (12) of the spindle drive (10).

3. Spindle drive (10) according to claim 1 or 2, characterized in that the control unit is integrated in a housing of the drive motor (20).

4. Spindle drive (10) according to one of the preceding claims, wherein the drive motor (20) has Hall sensors for detecting the actuating force.

5. Spindle drive (10) according to one of the preceding claims 1 to 3, wherein the drive motor (20) uses a voltage induced in motor coils of the drive motor to detect the actuating force.

6. Spindle drive (10) according to one of the preceding claims, wherein the control unit is designed to control the drive motor (20) as a function of the detected actuating force in order to provide at least one of the following closure element functions: - a closure element opening in response to pressure against the closure element; - a motor-assisted movement of the closure element; - a manual stopping of the closure element during a motor-assisted adjustment of the closure element; - a detection of contact with an obstacle during a motor-assisted adjustment of the closure element; and - a stopping of the closure element in the event of an imminent collision with an obstacle.

7. Spindle drive (10) according to claim 6, wherein the control unit is designed to deactivate at least one of the closure element functions in dependence on a switch-off signal of a vehicle control unit.

8. Spindle drive (10) according to claim 6, wherein the control unit is designed to receive a sensor signal from a vehicle sensor and to control at least one of the closure element functions in dependence on the sensor signal.

9. Spindle drive (10) according to one of the preceding claims, wherein the control unit is designed to prevent adjustment of the closure element by the drive motor (20) during vehicle movement.

10. Motor vehicle with a closure element and a spindle drive (10) according to one of the preceding claims, wherein the closure element is adjustable between an open position and a closed position by means of the spindle drive (10).

Images