Field of the Invention

The present invention relates to a self-locking safety belt buckle for use with a safety harness.

Background

When designing belt buckles for safety harnesses or similar, one design consideration is ease of use. The belt buckle should be easy to open, preferably by only using one hand, while at the same time being reliable so that it does not open unexpectedly.

Commonly available belt buckles are often either complicated, or run the risk of opening unexpectedly. That is, when a commonly available belt buckle is subjected to a tensioning force, such as when a user is hanging in a safety harness secured by the belt buckle, the safety measures in place may fail. For example, a belt buckle having two locking arms, that are usually required to be actuated simultaneously, may jam due to the tensioning force and the belt buckle may then open even though the two locking arms are actuated sequentially. Summary of the Invention

An object of the present invention is therefore to alleviate the abovementioned problems and provide a belt buckle that is easy to use, requiring only one hand to open, that reduces the risk of opening

unexpectedly when subjected to a tensioning force, and that is easy and cheap to produce.

The above and other objects which will be evident from the following description are achieved by a self-locking safety belt buckle according to the present invention.

According to a first aspect of the present invention, a belt buckle for locking two belt ends to each other is provided, said belt buckle comprising: a housing comprising a locking tongue receiving recess; two locking arms, wherein each one of said two locking arms is arranged at least partly inside said locking tongue receiving recess, each one of said two locking arms being configured to move translationally between a locking position and an unlocking position, and each one of said two locking arms comprising a first locking surface;

a locking tongue comprising a second locking surface and being configured to be received by said locking tongue receiving recess by moving said locking tongue in a first direction into said locking tongue receiving recess; and

wherein said housing and said two locking arms are configured such that applying a force to said locking tongue when said locking tongue is in said locking tongue receiving recess, in a second direction that is opposite said first direction causes said two locking arms to be biased towards said locking position.

Thus, a more secure belt buckle is achieved. This is due to the fact that tension applied on the two belt ends that are locked together forces the locking arms to even more firmly prevent the locking tongue from leaving the locking tongue receiving recess. The belt buckle of the present invention can thus be seen as a self-locking belt buckle, employing principles similar to a Chinese finger trap. In other words, the harder the belt buckle is loaded, the more securely it locks the two belt ends together. Thereby, jamming of the belt buckle due to the tensioning force between the two belt ends may be prevented, as the self-locking mechanism prevents the belt buckle from opening unintentionally.

The term“move translationally” is to be understood as meaning “moving without any rotation”. Thus, the two locking arms are configured to move between a locking position and an unlocking position by moving along a respective line.

According to one exemplary embodiment, said lines extend inside the locking tongue receiving recess.

According to one exemplary embodiment, said lines extend along a respective locking arm guiding recess arranged inside said locking tongue receiving recess. According to one exemplary embodiment, said line is a straight line.

According to one exemplary embodiment, the locking arms are not fixedly or rotationally connected to the housing. According to one exemplary embodiment, the locking arms are slidably arranged inside the housing.

According to one exemplary embodiment, said first locking surface is a surface extending from one end of each respective locking arm in a direction that is substantially perpendicular to said first direction.

According to one exemplary embodiment, the second locking surface is a surface arranged to mate with the first locking surface when the two locking arms are in the locking position and the locking tongue is inside the locking tongue receiving recess, thereby preventing the locking tongue from leaving the locking tongue receiving recess.

According to one exemplary embodiment, the first locking surface and second locking surface are angled such that the locking arms are biased towards the locking position when the second locking surface is moved towards and against the first locking surface.

According to one exemplary embodiment, said belt buckle has a locked state in which said locking tongue is received by said locking tongue receiving recess and said two locking arms are in said locking position, and an unlocked state in which said locking tongue is received by said locking tongue receiving recess and said two locking arms are in said unlocking position.

According to one exemplary embodiment of the present invention, said housing and said locking arms are configured such that applying a force to said locking tongue in a second direction that is opposite said first direction, when said belt buckle is in said locked state, causes said locking arms to be biased towards said locking position.

According to one exemplary embodiment of the present invention, said locking arms are caused to be biased towards said locking position by said locking tongue. Thus, the locking tongue may be caused to engage the locking arms and force them towards a locking position if a force is applied to said locking tongue in a second direction that is opposite said first direction. According to one exemplary embodiment, in said locked state, said locking arms are configured to prevent said locking tongue from leaving said locking tongue receiving recess by said first locking surface contacting said second locking surface.

According to one exemplary embodiment, said belt buckle further comprises biasing means configured to bias said locking arms towards said locking position.

According to one exemplary embodiment, said biasing means is at least one spring.

According to one exemplary embodiment, said locking arms are configured to move translationally between said locking position and said unlocking position along a locking direction, wherein an angle between said locking direction and said first direction is between 5° and 85°, more preferably between 15° and 75°, and most preferably between 25° and 65°.

According to one exemplary embodiment of the present invention, the first locking surface is arranged at an angle relative said locking direction.

According to one exemplary embodiment of the present invention, said angle between said locking direction and said first direction is the smallest angle between said locking direction and said first direction.

According to one exemplary embodiment of the present invention, an angle between a first reference line starting in a reference point on said locking surface and that is extending perpendicularly therefrom and a second reference line starting in said reference point and extending in a direction that is opposite the direction which said locking arms are biased towards is between 5° and 85°.

According to one exemplary embodiment, said housing comprises a respective locking arm guiding recess configured to guide the translational movement of each of the two locking arms between said locking position and said unlocking position.

According to one exemplary embodiment, said locking arm guiding recess is aligned with said locking direction.

According to one exemplary embodiment, said locking tongue has a locking arm displacing surface, said locking arm displacing surface being arranged so that said locking arms are displaced from a locking position to an unlocking position when said locking tongue is being received by said locking tongue receiving recess.

According to one exemplary embodiment of the present invention, the width of the locking arm displacing surface is larger than the part of the locking tongue receiving opening that is not obstructed by the locking arms when the locking arm is in the locking position. In other words, when the locking tongue is received by said locking tongue receiving recess, the locking arms are displaced from the locking position by means of interaction between the locking arm displacing surface and the locking arms.

According to one exemplary embodiment, said locking arm displacing surface is wedge-shaped.

By being wedge-shaped, the locking arm displacing surface of the locking tongue is better suited to displace the locking arms when the locking tongue is inserted into the locking tongue receiving recess.

According to one exemplary embodiment, said housing consists of two substantially identical housing halves, wherein each one of said two housing halves has an outer side and an inner side, and wherein said two housing halves are mounted to each other with said respective inner sides facing each other.

Thus, a less complex belt buckle housing is achieved as many components are symmetrical. This reduces production costs and allows for a simpler product. It also reduces investment costs for the producer, as fewer and/or simpler tools are required to produce the belt buckle.

According to one exemplary embodiment, said belt buckle further comprises a frame, wherein said housing is held at least partly inside said frame. Thus, the frame may be configured to support a majority of the load applied on the belt buckle, such that the housing may be made from a material that does not have to be as strong as would otherwise have been required. Thus, a cheaper housing and a cheaper belt buckle is achieved. Said frame may for example be made from a single sheet of metal. Said frame may be U-shaped, such that it covers both sides of the housing. The frame may be connected to the housing by means of conventional fasteners such as bolts or screws.

According to a second aspect of the present invention, a belt buckle for locking two belt ends to each other is provided, said belt buckle comprising: a housing comprising a locking tongue receiving portion;

a first and a second locking arm arranged at least partly inside said locking tongue receiving portion, said first and second locking arms being arranged for translational movement along a first and second direction, respectively, between a locking position and an unlocking position, and said first and second locking arms comprising a first and second locking surface, respectively;

wherein said locked state is a state in which said locking tongue is received by said locking tongue receiving portion and said first and second locking arm are in said locking position,

wherein said unlocked state is a state in which said locking tongue is received by said locking tongue receiving portion and said first and second locking arms are in said unlocking position or a state in which said locking tongue is not received by said locking tongue receiving portion,

wherein in said locked state, said first and second locking surfaces of said first and second locking arms are arranged to prevent said locking tongue from leaving said locking tongue receiving portion by contacting said locking tongue,

wherein in said locked state, a smallest angle between any one of said first and second direction and a contacting surface between said first and second locking surface and said locking tongue is greater than 5°.

Brief description of the drawings

The above, as well as additional objects, features and advantages of the present invention, will be better understood through the following illustrative and non-limiting detailed description of exemplary embodiments of the present invention, with reference to the appended drawing, wherein:

Figure 1 is an exploded view of a self-locking safety belt buckle according to one exemplary embodiment of the present invention, Figure 2 is a cross-sectional view of the self-locking safety belt buckle of Figure 1 ,

Figures 3a-c are cross-sectional views of the self-locking safety belt buckle of Figure 1 , when the belt buckle goes from an unlocked state to a locked state,

Figures 4a-c are cross-sectional views of the self-locking safety belt buckle of Figure 1 , when the belt buckle goes from a locked state to an unlocked state, and

Figure 5 is a perspective view of the self-locking safety belt buckle of Figure 1 , illustrating the symmetry of certain components

Figure 6 is an exploded view of a self-locking safety belt buckle according to one exemplary embodiment of the present invention.

Detailed description of preferred embodiments of the invention

In the present detailed description, embodiments of a self-locking safety belt buckle according to the present invention are mainly discussed with reference to drawings showing a belt buckle with components and portions being relevant in relation to various embodiments of the invention. It should be noted that this by no means limits the scope of the invention, which is also applicable in other circumstances for instance with other types or variants of belt buckles than the embodiments shown in the appended drawings. Further, that specific features are mentioned in connection to an embodiment of the invention does not mean that those components cannot be used to an advantage together with other embodiments of the invention.

The invention will now by way of example be described in more detail by means of embodiments and with reference to the accompanying drawings.

Figure 1 is an exploded view of a self-locking safety belt buckle 1 according to one exemplary embodiment of the present invention. The belt buckle 1 comprises a housing 100, the housing 100 having two housing halves 101. The belt buckle 1 further comprises two looking arms 200, two springs 901 , and a locking tongue 300. The belt buckle 1 further comprises a number of fastening means 903 used in the assembly of the belt buckle 1. The two housing halves 101 are substantially identical. The housing halves 101 have a belt receiving portion 103 for receiving one end of the belt that is to be secured with the belt buckle 1 , and a locking tongue receiving portion 105 located opposite the belt receiving portion 103. These portions as well as other portions and elements of the belt buckle of Fig. 1 are clearly seen in Fig. 2. The locking tongue receiving portions 105 of the two housing halves 101 collectively define a locking tongue receiving opening 107 and a locking tongue receiving recess 109. The locking tongue receiving opening 107 opens up to the locking tongue receiving recess 109, and the locking tongue receiving recess 109 is configured to receive the locking tongue 300 and a portion of each one of the two locking arms 200. The locking tongue receiving recess 109 is arranged so that the locking tongue 300 may be freely permitted to enter the locking tongue receiving recess 109, and then be locked in place therein by means of interaction with the locking arms 200.

Each one of the two housing halves 101 further comprises a locking arm opening 1 1 1 , and a locking arm guiding recess 113. The locking arm opening 1 1 1 is an opening that opens up to the locking tongue receiving recess 109 and through which a portion 201 of the locking arm 200 is configured to protrude once the belt buckle 1 is assembled. This allows a user to actuate the locking arms 200 between a locking position and an unlocking position by pressing on the portion 201 of the locking arms 200 that protrudes out of the locking tongue receiving recess 109 through the locking arm opening 1 1 1. The locking arm guiding recess 1 13 is a straight recess inside the housing 100, the locking arm guiding recess 1 13 being configured to guide a respective one of the two locking arms 200 in its translational movement relative the housing halves 101. Thus, when a user pushes on the portions 201 of the locking arms 200 that protrude through the locking arm opening 1 1 1 , the locking arm guiding recesses 113 guide the locking arms 200 so that they move along a predetermined, straight path. Each one of the locking arm guiding recesses 113 is further configured to receive and hold a respective one of the two springs 901 , so that when the locking arm 200 is moved along the locking arm guiding recess 1 13 towards the unlocking position, the spring 901 is compressed and the locking arm 200 is subjected to a force that pushes it back towards the locking position. In other words, the locking arms 200 are biased towards their locking position by means of the springs 901.

The locking tongue receiving recess 109 is slightly larger than the locking tongue 300 it is arranged to receive, so as to permit that the locking tongue 300 is angled relative to the housing 100. This increases the comfort for a user using the belt buckle 1 , as the housing 100 and locking tongue 300 may follow the shape of the user’s body, thus reducing the pressure on the user from the belt buckle 1.

The locking tongue 300 comprises a substantially arrow-shaped protrusion 301 , and a belt receiving portion 303. The arrow-shaped protrusion 301 may have other shapes as well, for example a mushroom-shaped protrusion. The arrow-shaped protrusion 301 and the belt receiving portion 303 are integrally connected to each other. The locking tongue 300 is symmetric over two perpendicular planes of symmetry, the two perpendicular planes of symmetry intersecting along a line extending from the arrow-shaped protrusion 301 and towards the belt receiving portion 303. However, the locking tongue may be asymmetric in certain embodiments of the invention, in order to prevent the locking tongue from being inserted in an incorrect rotational orientation. The arrow-shaped protrusion 301 has a wedge-shaped front 305, i.e. a V-shaped front. Adjacent to the wedge-shaped front 305 is a locking surface 307 that connects the wedge-shaped front surface 305 to a stem 309 of the arrow-shaped protrusion 301. The stem 309 has a width that is smaller than the width of the wedge-shaped front surface 305, thus creating an overhang between the wedge-shaped front surface 305 and the stem 309. The locking surface 307 is provided at this overhang. The locking surface 307 extends substantially perpendicular from the stem 309 and out towards the wedge-shaped front 305. The arrow-shaped protrusion 301 is arranged to be received by the locking tongue receiving recess 109, through the locking tongue receiving opening 107, and be held in place therein by means of interaction with the two locking arms 200. The locking tongue is described in more detail in relation to Figures 2-4. Connected to one of the two housing halves 101 is a protrusion or element 905 extending from the housing half 101 and inwards towards the locking tongue receiving recess 109. The protrusion or element 905 is arranged to prevent the locking tongue from being inserted in the incorrect rotational position by interacting with a corresponding recess 31 1 arranged on one side of the arrow-shaped protrusion 301 of the locking tongue 300. Thus, only if the locking tongue is inserted in the correct rotational position relative to the housing 100 may the protrusion or element 905 be aligned with the recess 31 1 on the locking tongue 300 and allow insertion of the locking tongue 300 into the locking tongue receiving recess 109. According to one example embodiment, the belt buckle does not comprise this protrusion or element 905.

The belt buckle 1 further comprises a rod-shaped element 907 for adjusting the length of the belt that the belt buckle 1 is to be used with. The rod-shaped element 907 is arranged between the two housing halves 101 at a position at the belt receiving portion 103. The skilled person readily understands how the rod-shaped element 907 for adjusting the belt length is arranged.

Figure 2 is a cross-sectional view of the self-locking safety belt buckle 1 of Figure 1. In Figure 2, only one of the two housing halves 101 is shown. Consequently, only one of the two locking arms 200 is shown.

The housing half 101 shown in Figure 2 comprises a locking tongue receiving recess 109. A locking arm 200 is arranged partially inside the locking tongue receiving recess 109, so that only a portion 201 of the locking arm 200 protrudes through the locking arm opening 1 11 in the housing half 101. The locking arm 200 is arranged to slide along a locking arm guiding recess 113 in the housing half 101 , and is arranged to be guided by the internal walls of the locking tongue receiving recess 109, the locking arm guiding recess 1 13 and the locking arm opening 1 1 1 , so that only linear movement of the locking arm 200 is permitted. Thus, the locking arm 200 may move between a locking position and an unlocking position by means of translational movement. The housing half 101 is further provided with a spring 901 arranged inside the locking arm guiding recess 113. This spring 901 biases the locking arm 200 towards the locking position by being compressed inside the locking arm guiding recess 1 13. The locking arm 200 comprises a locking surface 203 arranged to, when the locking arm 200 is in the locking position and the locking tongue 300 is received in the locking tongue receiving recess 109, prevent the locking tongue 300 from leaving the locking tongue receiving recess 109, thus locking the belt buckle 1. In Figure 2, the locking arm 200 is in the locking position but the locking tongue 300 has yet to be received by the locking tongue receiving recess 109.

Figures 3a-c are cross-sectional views of the self-locking safety belt buckle 1 of Figure 1 , when the belt buckle 1 goes from an unlocked state to a locked state. The first arrow A shows the direction in which the locking tongue 300 is inserted into the locking tongue receiving recess 109. The second arrow B shows the direction in which the wedge-shaped front 305 of the arrow-shaped protrusion 301 of the locking tongue 300 displaces the locking arm 200. The third arrow C shows the direction in which the spring 901 pushes the locking arm 200 once the locking tongue 300 has been received by the locking tongue receiving recess 109. In Fig. 3a, the locking tongue 300 has yet to be received by the housing 100. The locking arm 200 is in the locking position, obstructing a portion of the locking tongue receiving opening 107. In Fig. 3b, the locking tongue 300 has been moved in the first direction A so that it is halfway through the locking tongue receiving opening 107. The locking arm 200 has been forced outwards, in the direction indicated by the arrow B, by the arrow-shaped protrusion 301 of the locking tongue 300, such that it is in the unlocking position. In Fig. 3c, the locking tongue 300 has been fully received by the locking tongue receiving recess 109. The spring 901 has forced the locking arm 200 back into its locking position along the direction C, such that the locking surface 307 of the locking tongue 300 engages the locking surface 203 of the locking arm 200. Thus, the locking tongue 300 is prevented from leaving the locking tongue receiving recess 109.

Figures 4a-c are cross-sectional views of the self-locking safety belt buckle 1 of Figure 1 , when the belt buckle 1 goes from a locked state to an unlocked state. The fourth arrow D shows the direction in which a user pushes the protruding portion 201 of the locking arm 200, thus displacing the entire locking arm 200, in order to move the locking arm 200 to its unlocking position. The fifth arrow E shows the direction in which the locking tongue 300 is removed from the locking tongue receiving recess 109. In Fig. 4a, the locking tongue 300 has been fully received by the locking tongue receiving recess 109. The spring 901 biases the locking arm 200 towards its locking position, such that the locking surface 307 of the locking tongue 300 engages the locking surface 203 of the locking arm 200. Thus, the locking tongue 300 is prevented from leaving the locking tongue receiving recess 109. In Fig. 4b, the user pushes in the direction D on the portion 201 of the locking arm 200 that extends through the locking arm opening 1 1 1 , so that the locking arm 200 moves to its unlocking position. The locking tongue 300 may then leave the locking tongue receiving recess 109. In Fig. 4c, the locking tongue 300 and the housing 100 have been separated from each other, by moving the locking tongue 300 along the direction E, and the belt buckle 1 has

consequently been unlocked.

Figure 5 is a perspective view of the self-locking safety belt buckle 1 of Figure 1 , illustrating the symmetry of certain components. Flere, it is clear how the two housing halves 101 , the two locking arms 200, and the two springs 901 are identical. Thus, when the two housing halves 101 are connected to each other face-to-face, the two locking arms openings 1 11 are arranged on either side of the housing 100. This means that the user of the belt buckle 1 has to actuate the two locking arms from both sides of the belt buckle 1 at the same time in order to remove the locking tongue 300 from the locking tongue receiving recess 109.

Figure 6 is an exploded view of a self-locking safety belt buckle 1’ according to one exemplary embodiment of the present invention. The belt buckle 1’ shown herein shares the features of the self-locking safety belt buckle 1 of Figure 1 , with the following exceptions. The belt buckle 1’ of Figure 6 further comprises a frame 904, to which the two housing halves 101’ are connected. Furthermore, the belt receiving portion 103’ is formed as a separate component from the two housing halves 101’. Thus, in the belt buckle of Figure 6, the housing halves 101’ primarily define the mechanism with which the locking tongue 300’ is locked in place. The frame 904 is arranged such that the two housing halves 101 the locking arms 200’, the springs 901 and the belt receiving portion 103’ may be housed therein and connected thereto. The skilled person readily understands that features and embodiments of one exemplary embodiment of the invention may be applied to other embodiments of the present invention as well.

Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to“a/an/the [element, device, component, means, step, etc.]” are to be interpreted openly as referring to at least one instance of said element, device, component, means, step, etc., unless explicitly stated otherwise. Furthermore, any reference signs in the claims should not be construed as limiting the scope.