The invention relates to a door lock with a noise-dampening deadbolt arrangement according to the preamble of Claim 1 . It is previously known to use deadbolts made from hard plastic or some other lightweight non-magnetic material in door locks, especially in so-called intermediate door locks indoors, in different applications, and they have also been used in magnetic locks in which the attraction between the magnets of the deadbolt and the magnets of the strike plate of the door frame forces the deadbolt out. The deadbolt being relatively light due to the selected material, correspondingly, less force is needed to move it. However, when the deadbolt is moved to its extended position and back to its retracted position in the lock case, noise is generated because the movements are obstructed by suitable stoppers and the deadbolt hits them with a bang. When the door is being closed, the deadbolt is forced out of the lock case by the attraction between said magnets, or, also if the strike plate is made from magnetic metal, such as iron. Thus, the end of the deadbolt hits the strike plate with a bang. On the other hand, when the door closes further, the deadbolt moves from the hole in the strike plate into the strike plate. This movement being obstructed by a stopper in the lock case, the body part of the deadbolt, once again, hits said stopper with a bang.

The invention aims at providing a door lock having a novel deadbolt arrangement and enabling a substantial reduction of the above-described noise caused by the movements and operation of the deadbolt.

The objects of the invention can be achieved as described in more detail in Claim 1 and the rest of the Claims. According to the invention, the end of the deadbolt projecting from lock case includes a sound-dampening part arranged on the deadbolt in such that it, when the door is being closed, hits the strike plate of the door frame and slides along the strike plate until the deadbolt lies at the hole in the strike plate. This is an advantageous and effective way to damp- en the noise from this unpleasant noise source involved in the operation of a door lock.

In practice, said sound-dampening part is made from plastic or the like that is softer than the rest of the deadbolt, such as thermoplastic elastomer, and, pref- erably, it can be injection-molded onto the end of the deadbolt. To ensure that said sound-dampening part stays on the end of the deadbolt, the joint between them preferably comprises a dovetail joint.

In alternative embodiments, said sound-dampening part is arranged to only cover a part of the end of the deadbolt. The structure of the deadbolt is basically such that its body part inside the lock case has a protrusion transverse to the direction of movement of the deadbolt which, together with a counterface inside the lock case, defines the projecting length of the deadbolt. To eliminate the above-mentioned second noise source involved in the operation of a deadbolt, said protrusion is preferably provided with a second sound-dampening part adapted to hit said counterface.

In the following, the invention will be explained by means of an example with reference to the accompanying schematic drawings in which

- Figure 1 is a partial section view of a door lock according to the invention when installed on a door, with the door closed and with the deadbolt of the lock in the hole in the strike plate,

- Figure 2 is an enlarged top and end section view of the deadbolt of the door lock,

- Figures 3a, b and c show different embodiments of the noise-dampening arrangement of the deadbolt, - Figure 4 illustrates the cooperation between the deadbolt and the strike plate of the door lock when the door is being closed, and

Figure 5 illustrates the magnetic flux of the magnets of the deadbolt. In the drawings, reference numeral 1 refers to a door with an embedded lock case 3 and a deadbolt 6 adapted to move reciprocally therein, and reference numeral 2 refers to a door frame with a lock strike plate 4 and a hole 4a therein for the deadbolt in a manner known per se. The deadbolt 6 has an end 6a which, when the lock is closed, is located in the hole 4a in the strike plate, as shown in Figure 1 , and a body part 6b which is located inside the lock case 3 all the time. The deadbolt 6 also has embedded permanent magnets 7 cooperating with a magnet 5 in the hole 4a of the strike plate such that the magnet 5 in the strike plate, when the door is being closed, pulls the end 6a of the deadbolt out of the lock case. When the deadbolt 6 lies at the hole 4a in strike plate, the deadbolt is moved into the hole 4a by the magnetic forces.

The lock case 3 contains an operational shaft 1 1 provided with transmission means, not shown in more detail, for push handle operation, the deadbolt thus being retractable, in order to open the door, into the lock case by means of the transmission element 12 shown in Figure 1 . In this case, the lock case additionally contains a second operational shaft 14 from which the deadbolt, in a manner known per se, can be double-locked in certain applications, such as toilets. The double-locking is carried out by moving a double-locking element 15, from the operational shaft 14, in the direction of the arrow, to lie against the rear part of the end 6a of the deadbolt. At the same time, as the double-locking element 15 also turns the transmission element 12 towards the end 6a of the deadbolt, the transmission connection from the transmission element 12 to the operational shaft 1 1 breaks. Since this represents a technique known per se, it will not be described further.

As shown in the figures, the end 6a of the deadbolt is provided with a sound- dampening part 8 made from thermoplastic elastomer, for example. It can be, for instance, injection-molded onto the end of the deadbolt. As shown in Figure 2, the part 8 can additionally be provided with a dovetail joint to ensure that it stays in place. The part 8 can have different embodiments, as illustrated in Figures 3a, b and c. Therefore, the end 6a of the deadbolt does not have to be en- tirely covered by the part 8, but what is essential is that it is installed in such a way that it, when the door is being closed, first hits the strike plate 4 and slides along it, as shown in Figure 4, until the deadbolt 6 is located at the hole 4a in the strike plate, where the deadbolt 6 is moved into the hole 4a, to the position shown in Figure 1 , by the attraction between the magnets 5 and 7.

Figures 5a and 5b illustrate the magnetic flux generated by the magnets 7 of the deadbolt 6 and its effect on the position of the deadbolt with respect to the forend 3a of the lock case. Magnets always try to move to a position where their end lies at metal, herein into the aperture in the forend 3a. Figure 5a shows a situation where the door has been opened by retracting the deadbolt 6 into the lock case 3 by means of the door handle. The end of the magnets 7 now being located in the aperture in the forend 3a, the deadbolt 6 stays in this position while the door is open. If the deadbolt, for some reason, gets out into the position shown in Figure 5b, it must be pushed into the lock case before closing the door.

Based on Figure 5b, it can also be stated that the magnetic flux generated by the magnets 7, in addition to the attraction between the magnets 7 of the dead- bolt and the magnet 5 in the hole 4a in the strike plate, is ideal for ensuring that the deadbolt 6 normally stays in the hole 4a in the strike plate, even without any double-locking means in the lock.

As also appears from the Figures, the body part 6b of the deadbolt has a transverse protrusion 9 that, together with a counterface 13 inside the lock case, defines the projecting length of the deadbolt 6. As the attraction between the magnets pushes the deadbolt out into the hole 4a in the strike plate, the protrusion 9a hits the counterface 13 with a bang. In order to dampen the noise caused by this, the protrusion 9 is provided with a second sound-dampening part 10 that hits the counterface 13 in this situation. As Figures 3a, b and c show, even this sound-dampening part can have different embodiments comprising elements on different sides of the body part 6b of the deadbolt. Preferably, this part 10 can also be made from thermoplastic elastomer. Further, it can be added that, naturally, the element comprising the counterface 13 inside the lock case 3, preferably also can function the other way around, i.e. to obstruct, together with a second protrusion 1 6 on the body part 6b of the deadbolt, the movement of the deadbolt 6 into the lock case 3. The invention is not limited to the above-described embodiment but several variations can be envisaged within the scope of the accompanying Claims.