FIELD OF THE INVENTION

The invention relates to a utility knife.

BACKGROUND OF THE INVENTION

Such a utility knife is known from DE 10 2016 008 724 [U.S. Pat. No. 10,478,977]. It comprises a housing and a blade holder relatively movable between a rear position and a cutting position. A return device in the form of a spring urges the blade holder into the rear position. In the rear position, the blade is retracted into the housing to the extent that the user cannot touch the cutting edge and therefore cannot injure himself. In the cutting position, the blade projects out of the front opening in the housing such that a cutting process is possible.

OBJECT OF THE INVENTION

The object of the invention is to design the return device such that it can be produced in a cost-effective manner. Furthermore, the return device is intended to allow the utility knife to be assembled in a simple manner. In addition, the return device is intended to be configured such that the return force can be varied by simply altering the construction.

SUMMARY OF THE INVENTION

The utility knife of this invention comprises a housing and a blade holder relatively movable between a first position and a second position. The first position is e.g. a rear safety position in which the blade is contained in the housing such that a user cannot touch the cutting edge of the blade. The second position is e.g. a blade-change position in which the blade extends out of the housing such that it is possible to change the blade. The second position may e.g. alternatively also be a cutting position in which the blade is moved out of the housing to the extent that a cutting process is possible.

Movement of the blade holder may e.g. be straight-line, rotary, or of a mixed nature with straight-line and rotary components. The blade holder may e.g. be movable on a straight or curved path.

In addition, the utility knife comprises a return device comprising a spring that can urge the blade holder into the first position relative to the housing.

The housing may have multiple parts. In particular if these parts are immovable relative to other housing parts and are rigidly connected thereto, they shall fall under the term “housing” in the following.

The return device comprises first return means and second return means. The first return means are mounted on the housing or blade holder. The second return means are mounted on the other element, i.e. on the blade holder or the housing. The first return means comprise a movable element and a spring. The movable element is connected to the spring and is urged in a travel direction by the spring. The movable element can e.g. perform a rotary movement, a straight-line movement, or a mixed movement having rotary and straight-line components. The movable element interacts with the blade holder and the housing and urges the blade holder toward the rear position at least in one movement region of the blade holder.

The movable element e.g. has a contact surface, which is in contact with a counter surface of the housing or the blade holder and is movable relative to the counter surface. The second return means comprise the counter surface. If e.g. the first return means are mounted on the blade holder, the contact surface is in contact with the second return means of the housing. If the first return means are mounted on the housing, the contact surface is in contact with the second return means of the blade holder.

The counter surface e.g. comprises at least two regions, with a second region having a different orientation from the first region. The movable element is in engagement with one of the at least two regions of the counter surface, for example depending on the position of the blade holder. The counter surface e.g. forms a sliding path, and the contact surface is a sliding surface. Alternatively, the contact surface could for example be formed on a rolling element, and the counter surface forms a rolling path.

The contact surface may e.g. be formed on a projection of the movable element.

The spring is e.g. a compression spring or a tension spring. Springs of this kind are affordably available on the market in different sizes. In particular, a tension spring is simple to mount and can be easily fastened to the components to be urged.

Within the meaning of the invention, a spring is any device made of an elastically deformable material which exerts a return force after the deformation. As long as this property is provided, the term is not dependent on the shape and the material of the device. The spring may e.g. be made of spring steel, plastics material, or a natural substance.

The movable element interacts e.g. with differently oriented surfaces of the housing or blade holder, which form the counter surface. The orientation of the surface is indicated in the following by the direction of the surface orthogonal. The orientation of the different surface regions may be such that different components of the spring force act on the blade holder in the return direction (direction of the first position). For example, a first force acts on the blade holder in the return direction between the first position and an intermediate position, and a second force or no force acts on the blade holder in the return direction between the intermediate position and the second position. The first force differs from the second force.

The blade holder can e.g. be moved between a first, safety position, a cutting position, and a second, blade-change position.

The position of the blade holder e.g. controls the contact of the movable element with the relevant region of the counter surface.

For example, when moving the blade holder between the rear position and the cutting position, the movable element can be in contact with a counter surface, which urges the blade holder into the rear position. In the blade-change position, the movable element can be in contact with a counter surface such that the blade holder is not urged in the return direction or is only urged in the return direction with a low force, and therefore no movement takes place. This may e.g. be the case if the blade holder is urged in a direction in which it does not have a degree of freedom.

In a second region of the counter surface, the force acting on the blade holder in the return direction may e.g. be less than in a first region. The first region includes the safety position, for example. The second region includes the cutting position, for example.

A first surface, e.g. a surface of the blade holder or the housing which is in contact with the movable element, is e.g. directed in the travel direction of the blade holder such that the blade holder is urged into the rear position. The surface orthogonal is e.g. parallel with the travel direction of the blade holder or has components that are similarly parallel.

A second surface, e.g. a surface of the blade holder or the housing, which is in contact with the movable element, is e.g. directed relative to the travel direction of the blade holder such that the blade holder is not urged into the rear position or is urged into the rear position with less force. The surface orthogonal is e.g. directed at right angles to the travel direction of the blade holder or has components that are directed in such a manner. If the surface orthogonal is directed at right angles to the travel direction of the blade holder, the movable element cannot transfer any force to the blade holder in the direction of the rear position. Therefore, the blade holder remains in the set position. In this case, a proportion of the spring force is directed in a direction other than the return direction and is e.g. absorbed by the housing.

The counter surface is e.g. formed as a control surface over which the movable element travels when the blade holder moves between the rear position and the blade-change position. At least two differently oriented surfaces are e.g. formed on one counter surface. In this case, the first return means are mounted on the housing or the blade holder and the counter surface of the second return means is mounted on the other element, i.e. the blade holder or the housing. A guide element of the movable element can be guided on the counter surface. Depending on the orientation of the counter surface with which the movable element is in contact, the blade holder is urged into the rear position with the full spring force if the entirety of the spring force is acting on the blade holder in the return direction, is urged into the rear position with less force if only some of the spring force is acting on the blade holder in the return direction, or is not urged into the rear position at all if the spring force is not acting on the blade holder in the return direction. In this sense, spring force is the spring force transferred from the movable element to the blade holder.

The movable element is e.g. a lever, for example a two-armed lever. The lever is pivotable about a fixed pivot axis or a movable pivot axis. A lever arm e.g. comprises the contact surface. For example, a second lever arm is urged by the spring.

For example, the spring and the movable element are fastened to the blade holder, with one end of the spring being connected to the blade holder and the other end of the spring being connected to the movable element.

Alternatively, the spring and the movable element are fastened to the housing, and one end of the spring is connected to the housing and the other end of the spring is connected to the movable element.

The housing is e.g. provided with at least one first stop and the blade holder is provided with a counter-stop. In this case, the contact between the stop and the counter-stop determines the cutting position, for example. This means that the blade holder can only be moved out of the rear position toward the cutting position until the stop and the counter-stop are in contact and therefore determine the cutting position.

For example, the housing is provided with a second stop, which is in contact with the counter-stop in a blade-change position and prevents any further movement in the travel direction counter to the rear position. In the blade-change position, the blade holder is e.g. moved beyond the cutting position relative to the rear position.

For example, a stop on the housing which defines the cutting position can be reached via a first movement path and a stop which defines the blade-change position can be reached via a second movement path. For example, a region of the blade holder is flexibly movably mounted such that the counter-stop can be moved between the first movement path and the second movement path. The counter-stop can e.g. be shifted between the movement paths by means of actuation. If the counter-stop is then moved on the first movement path, movement of the first stop is limited, and if the counter-stop is moved on the second movement path, movement of the second stop is limited.

The first movement path and the second movement path can be separated from one another by a wall such that the counter-stop cannot move between the first movement path and the second movement path, at least in one movement region. For example, the counter-stop can be moved between the first movement path and the second movement path in the rear position.

One embodiment of the invention is described by way of example in the following description of the figures, also with reference to the schematic drawings. Here, for the sake of clarity, even if different embodiments are involved, identical or comparable parts or elements or regions have been denoted by identical reference signs, sometimes with the addition of lower-case letters or apostrophes.

Features that are only described, set out or disclosed in relation to one embodiment can also be provided in any other embodiment of the invention within the scope of the invention. Even if they are not shown in the drawings, such amended embodiments are covered by the invention.

All the features disclosed are essential to the invention per se. The content of the disclosure of the cited documents and the prior art devices described are hereby incorporated into the disclosure of the application in their entirety, also for the purpose of incorporating individual features or a plurality of features of the subjects disclosed therein into one or more claims of the present application. Even if they are not shown in the drawings, such amended embodiments are also covered by the invention.

