DETAILED DESCRIPTION

[0035] A first embodiment of the invention related to a vehicle door lock indicator device will now be described by way of example in the following with reference to the accompanying drawings.

[0036] With reference to FIGS. 1 a and 1 b, a first embodiment of a vehicle door lock indicator device 1 is disclosed by way of example. A door lock knob 16 is operatively connected to one actuator 2 having two SMA members 2 a, 2 b. Hence, said actuator 2 is substantially made of shape memory alloy (SMA) and arranged to be powered by an energy source 3 . The lock knob 16 is operatively connected to a pivotal controller 18 by a hinged pin 4 . The hinged pin 4 has a joint connection 5 a to the controller 18 and a joint connection 5 b to the lock knob 16 . Both SMA members 2 a, 2 b are arranged to the pivotal controller 18 . The function will be described more in detail in a further section.

[0037] An actuator to be used in connection with the invention is substantially made of shape memory alloy (SMA). In the preferred embodiment the actuator comprises at least one SMA member. Depending on the forces on the vehicle door lock indicator device 1 and the SMA member used it is understood that the diameter may be varied. For use in a vehicle door under normal conditions the thickness interval of between 10 μm and 1 mm, preferably between 10 μm and 100 μm for the SMA member used as actuator is appropriate. This thickness will give an appropriate response and cycle time, which is essential for this kind of applications. It is hence preferred to use additional SMA members in order to provide more force rather than increase the dimension of an individual SMA member. By the inventive vehicle door lock indicator device 1 , around 20 cycles per minute can be accomplished. According to the preferred embodiment the SMA member used is a thin wire with an essentially circular cross section shape. Other shapes of the SMA member cross section are possible.

[0038] Vehicles sometimes experience significant violence resulting in extreme loading on at least parts of the vehicle. In order to control the vehicle door lock indicator device 1 in extreme conditions the vehicle door lock indicator device 1 has at least one back-up member for providing additional force in extreme conditions.

[0039] The back-up member has a cross-sectional area that is preferably between 4 and 25 times greater than a shape memory alloy member in the vehicle door lock indicator device 1 in question. The back-up member, when activated, will, need more power to actuate the vehicle door lock indicator device but will also add significant force compared to normal operational conditions and hence the extreme control conditions can be fulfilled. The response time of the vehicle door lock indicator device 1 in extreme control condition can be longer than in the normal operational conditions.

[0040] There are at least two factors making SMA members appropriate for use as actuators. They undergo a phase deformation, changing the crystalline structure of the material, from the Martensite phase to the Austenite phase in a relatively low temperature range. An SMA member can “remember” its previous shape after having been plastically deformed. If a sample, being in its low temperature phase (Martensite), is plastically deformed to a new shape it will return to its original shape when heated to its high temperature phase (Austenite). Since the modulus of elasticity and yield stress are much higher in the Austenite phase it will not only return to its original shape, but when doing so, also produce a force much higher than required for deformation. The difference in deformation force and recovery force can be used for actuation. The original shape is “taught” to the material by forming and fixing it to the desired shape, followed by heating to a temperature much higher than any normal operational temperature. Normally a sufficient heat treatment for shape memory “teaching” is around 500° C. and lasts for a few minutes. As mentioned the characteristics of SMA members change dramatically when the temperature is increased. In the materials appropriate for actuation the modulus of elasticity is normally more than doubled and the yield stress more than four times higher, when the material is heated above its transformation temperature. The changes are reversible and fully reproducible. The heating of the SMA member is conveniently done using Ohmic heating, that is by letting current pass through the material, wherein the electric resistance of the material causes a temperature increase.

[0041] There are various Shape Memory Alloys suitable for use in an embodiment of the present invention. Nitinol is an example of such a Shape memory alloy. Nitinol is a corrosion resistant, super elastic Nickel-Titanium alloy. Being super elastic, Nitinol can be stretched up to 10% without rupturing. When contracting, it can produce an actuation stress of more than 600 MPa in extreme cases, but should normally not be subjected to more than 170 MPa. Furthermore, when stretched less than 5%, Nitinol is also fatigue persistent. Required electric potential for power supply is normally a few volts. The temperature characteristics for the phase change is highly dependent on the content ratio of the alloy components. There exist in addition to various types of Nitinol also for example Fe-based and Cu-based shape memory alloys. Given the above data it is understood by a man skilled in the art of vehicle door lock indicator devices 1 that the length of the SMA members is an important design tool in order to provide a long-lasting and reliable vehicle door lock indicator device.

[0042] Now, referring again to FIGS. 1 a,b the function of a first embodiment of the vehicle door lock indicator device according to a first aspect of the invention will be described. The pivotally mounted controller 18 has two shape memory alloy members 2 a, 2 b connected thereto. One shape memory alloy member 2 a is arranged at the top of the controller 18 and another shape memory alloy member 2 b is arranged at the bottom of the same controller. When the current is applied to one of the SMA members 2 a, 2 b, respectively, the SMA member 2 a, or 2 b shrinks due to the rise in temperature in the respective SMA member. This deformation generates a force resulting in a movement of the lock knob 16 . In FIG. 1 a the current is applied to the below arranged SMA member 2 b, which has initiated a motion downwards of the lock knob 16 to the first position. This is further illustrated by the arrows in the figure. In FIG. 1 b the current is applied to the above arranged SMA member 2 a, which has initiated a motion of the lock knob 16 to the second position. The initiated pivotal movement of the controller 18 is indicated by an arrow in FIGS. 1 a and 1 b. Based on the position of the lock knob 16 a signal comprising information to a vehicle door system may be transmitted. The lock knob 16 is also manually movable between said first and second positions. During such a motion a switch (not shown) is triggered for providing current to the corresponding SMA member 2 a and 2 b, respectively, in order to control the motion of the vehicle door lock indicator device 1 and provide a signal to the vehicle door system.

[0043] Now, referring to FIG. 2 , wherein an alternative embodiment according to the first aspect of the invention is disclosed. Most features are common with the first described embodiment and therefore not described again in detail. An actuator 2 includes shape memory alloy is arranged to the vehicle door lock indicator device 1 . The actuator 2 describes a path with a suitable length for achieving the desired motion of the lock knob 16 . The lock knob 16 is shown in the first position from which the lock knob 16 is movable either manually by pulling the lock knob upwards or by means of electric actuation of the actuator 2 . It is realized that one additional SMA-member can be arranged to the lock knob in order to achieve a motion in both ways. This is schematically indicated by arrows in FIG. 2 . A stopper 17 is advantageously provided on the lock knob 16 to reduce the risk of damage, e.g. if the lock knob is being heavily pulled. Although not shown in the drawings it is known to make the head of a lock knob wider. This will reduce the risk for damage if the lock knob is being heavily pushed.

[0044] In FIGS. 3 a - 3 d a further preferred embodiment of the first aspect of the invention is disclosed. Compared to prior described alternative embodiments this vehicle door lock indicator device 1 includes a flipper 13 . The flipper 13 is pivotally arranged to the vehicle door lock indicator device 1 and operatively connected to a lock knob 16 . A spring 9 , for providing return force to the vehicle door lock indicator device 1 , is arranged in one end to the flipper 13 . The flipper 13 mainly consists of a claw 14 and a pawl 15 . The lock knob 16 is provided with a stopper 17 . In FIG. 3 a the lock knob is in the second position. When the lock knob 16 is moved to the first position, wherein the motion is activated by a gentle push on the lock knob 16 , the claw 14 engages with the pawl 15 just before the actuator 2 is fully shrunk. This is shown in FIG. 3 b. When the lock knob 16 is in the first position and is actuated by a gentle push or click, the actuator 2 continues the pulling operation and during this further motion the claw 14 is adapted to release the pawl 15 . This is conveniently accomplished by providing a slope at one side of the bottom of the mouth of the claw 14 , as indicated in FIG. 3 c. Since the shape memory alloy of the actuator 2 cools rapidly the lock knob 16 will quickly resume to the second position. The spring 9 is arranged to add force in order to control the motion in this step. This is further illustrated in FIG. 3 d.

[0045] Now referring to FIG. 4 , wherein a vehicle door system 12 according to a second aspect of the invention is illustrated schematically. Since the vehicle door lock indicator device 1 has the advantage of allowing for an electric system, it is understood that said actuator 2 is well equipped to be activated by a control unit 7 . The control unit 7 preferably also controls a latch assembly 10 of the vehicle door system 12 .

[0046] Preferably, the control unit 7 is used for controlling the period of time during which the door lock knob 16 is held in the second position. After that period, if not further activated, the lock knob 16 will resume the first position. Furthermore, the control unit 7 can be given a threshold value for the maximum of allowable repeated motions, between the first and second position of the lock knob 16 , during a time interval, in order to reduce the risk for overheating caused by e.g. “playing”.

[0047] The control unit 7 is, preferably, but not necessarily provided with a receiver (not shown) that will react on a signal transmitted from the vehicle door lock indicator device 1 . Suitably, the control unit 7 , has a wireless connection with a key or a key fob 8 . The locking and unlocking logic may be provided at least partly in the key or key fob 8 .

[0048] The procedure to unlock and open a closed and locked vehicle door with a vehicle door system 12 according to a second aspect of the invention, including a vehicle door lock indicator device 1 , will now be described. When activated, the vehicle door lock indicator device 1 sends a signal to the control unit 7 . When the actuated vehicle door lock indicator device 1 is moved from the first to the second position, the control unit 7 activates the locking and unlocking logic. The vehicle door will become unlocked, the latch assembly 10 unlatched and the vehicle door may be opened.

[0049] Referring to FIG. 5 , wherein the vehicle door system 12 according to a further preferred embodiment of the second aspect of the invention is presented. In addition to the first described embodiment of the second aspect of the invention the vehicle door system 12 further comprises a handle device 11 The control unit 7 controls the vehicle door-lock indicator device 1 , the handle device 11 and the latch assembly 10 . According to the further preferred embodiment the control unit 7 controls these devices by sending and receiving signals. The vehicle door lock indicator device 1 , the handle device 11 and the latch assembly 10 are able to transmit information within the vehicle door system 12 in combination with the transmitted information from the control unit 7 .

[0050] It is also an object of the present invention to provide a vehicle 20 , comprising at least one vehicle door lock indicator device 1 according to the invention. Preferably, the vehicle is provided with an embodiment of the inventive vehicle door system 12 . Such vehicle 20 will have considerable space for safety arrangements in the sides of the vehicle. Other resulting benefits will be apparent from the above given description. A vehicle 20 according to a preferred embodiment of the invention is shown in FIG. 6 . The vehicle door lock indicator device 1 and the vehicle door system 12 of the vehicle 20 are well adapted to be used as a part of a central locking system.

[0051] The present invention should not be considered as being limited to the abovedescribed embodiments, but rather includes all possible variations covered by the scope defined by the appended claims. It is understood by a man skilled in the art that the exact shape of the components and members of the vehicle door lock indicator device 1 can be varied in order to achieve alternative embodiments of the invention. Especially, the different states of the vehicle door system during actuation can be varied due to the flexibility of the vehicle door system enabled by the invention.

[0052] According to a preferred embodiment a local accumulator is used as the energy source 3 . it is understood by a person skilled in the art that a central energy source can be used to provide the vehicle door lock indicator device 1 with power. It is of course important to create a reliable power system to the vehicle door lock indicator device 1 . Hence, a central and local energy source system working together would be appropriate for this invention. However, the exact manner, in which power is supplied to the vehicle door lock indicator device 1 is not crucial for the present invention.