EP3061897A1

EP3061897A1 - Door closer with a cam drive and method for manufacturing a door closer with a cam drive

Info

Publication number: EP3061897A1
Application number: EP15156924.1A
Authority: EP
Inventors: Jackson Leong; Wee Kong Tam; Karthikeyan Papaiyan
Original assignee: Dorma Deutschland GmbH
Current assignee: Dormakaba Deutschland GmbH
Priority date: 2015-02-27
Filing date: 2015-02-27
Publication date: 2016-08-31

Abstract

The invention relates to a door Closer (1) comprising a housing, a spindle (2) with a cam surface (3) whereby the spindle (2) extends through an opening of the housing, a first piston (4), wherein the spindle (2) is connected to the first piston (4) via a cam drive (5), wherein the cam drive (5) allows a translation of a longitudinal movement (LM) of the first piston (4) into a rotational movement (RM) of the spindle (2), whereby the cam surface (3) contacts the first piston (4),whereby the first piston (4) comprises a spherical cam contact body (6) whose surface is in contact with the cam surface (3) of the door closers cam drive (5).

Description

The present invention regards to a door closer with a cam drive and a method for manufacturing a door closer with a cam drive.
Door closers are commonly known from the prior art. So called cam-action door closers have found wide spread application because of their beneficial momentum-curve, which provide an optimized opening and closing behavior for the user.
In such conventional cam-action door closers a spindle is connected to a piston via a cam drive, wherein the cam drive allows a translation of a longitudinal movement of the piston into a rotational movement of the spindle whereby the cam surface contacts the first piston. An example of such an arrangement known in the art is shown in Fig. 1a and Fig. 1b.
Fig. 1a and Fig. 1b show a piston 4 comprising a roller 16 which is rotatably mounted around the bolt 17 within a recess of the piston 4. A portion of the roller 16 extends from the recess and stands in contact with a cam surface of a cam positioned on or at the spindle of the door closer. Further, the cam drive comprises a retaining sleeve pin 18 and the pin 19. These pins are necessary as to maintain a line contact between the cam and the roller 16. Without these pins 18,19 the piston assembly could rotate within the closer housing which would cause the cam drive at least not to work properly as not to fail completely.
As it can be seen from the Fig. 1a and Fig.1b, many different components are required for build up such a conventional cam drive. This results in high cost due to material usage of individual components and long cycle time due to the complexity of the assembly.
It is hence the objective of this invention to provide a cam drive door closer which is reduced in complexity and cheaper and faster to manufacture compared to conventional door closers comprising a cam drive.
The result of this objective is achieved by the features of independent claims 1 and 13.
The door closer according to this invention comprises a housing, a spindle with a cam surface whereby the spindle extends through an opening of the housing, a first piston wherein the spindle is connected to the first piston via a cam drive, wherein the cam drive allows a translation of a longitudinal movement of the first piston into a rotational movement of the spindle, whereby the cam surface contacts the first piston, whereby the first piston comprises a spherical cam contact body whose surface is in contact with the cam surface of the door closers cam drive.
In replacement of the roller used in conventional cam drive designs so far, a spherical cam contact body is be used instead to serve the function of a cam follower. As a result of the spherical shape of the contact body, only a single point contact is maintained with the cam, unlike a line contact with current roller designs. This point contact does not require the piston to maintain orientation alignment with the cam when driven. Therefore, with the invention, the types and complexity of components in a piston assembly is greatly reduced. These include the omission of at least two pins, as shown in Fig.1b which is has been so far necessary for alignment maintenance with the cam. The assembly of the piston arrangement is also very much simplified as compared to the known conventional designs.
A door closer according to this invention is a mechanical door closer or a door closer with an electromechanical or electrohydraulic drive.
According to a preferred embodiment of the invention, the spherical cam contact body is ball shaped. The spherical cam contact body may be a readymade steel ball instead of a turned part.
To ensure a high durability and operational safety of the door closer it is beneficial that the spherical cam contact body shows a surface hardness of at least 50 HRC measured according to DIN EN ISO 6508-1. To allow a low friction it has become apparent that a surface finish of Ra < 0.3 measured according to DIN EN ISO 4287 is to be preferred, especially when the spherical cam contact body is covered by a hydraulic oil. It has further become evident that the spherical cam contact body may have an E-Modulus in the order of 190 - 210 GPa.
For ensuring that no momentum is transferred between the spherical cam contact body and the first piston, the spherical cam contact body may be rotatably mounted in or to the first piston.
To assure a single point contact between the cam and the spherical cam contact body it is preferable that the cam surface which is in contact with the spherical cam contact body is planar.
For further improving the durability and operational safety, the door closer according to this invention may have a cam surface with a surface hardness of at least 50 HRC measured according to DIN EN ISO 6508-1. The surface roughness of the cam surface in is Rz < 6.3 measured according to DIN EN ISO 4287 to ensure a smooth and durable movement of the cam surface against the spherical cam contact body.
For providing a reception for the spherical cam contact body, the first piston may comprise a recess for the bearing of the spherical cam contact body.
It is preferred, that the recess is of cylindrical shape or of spherical shape.
It is further preferred that the diameter of the recess in the first piston is 101%-103% of the diameter of the spherical cam contact body.
It can also be envisaged, that the spherical cam contact body may be mounted in the recess of the first piston by means of a crimp like bearing.
For reducing the friction within the cam drive assembly, it may be possible that the spherical cam contact body is mounted in the recess together with a plurality of freely movable spherical anti-friction bodies.
The spherical ant-friction bodies show special beneficial performance behaviour within the door closer according to this invention, when the spherical anti-friction bodies have a surface hardness of at least 50 HRC measured according to DIN EN ISO 6508-1. To allow a low friction it has become apparent that a surface finish of Ra < 0.3 measured according to DIN EN ISO 4287 is to be preferred, especially when the spherical anti-friction bodies are covered by a hydraulic oil. It has further become evident that a spherical anti-friction body may have an E-Modulus in the order of 190 - 210 GPa.
It has been proven to be even more beneficial with regards to friction reduction and operational safety of the door closer according to this invention, when the spherical anti-friction bodies may have a diameter which is 5-80% of the diameter of the spherical cam contact body.
For further reducing the complexity and different parts in the door closer design according to this invention, it may further be preferred, that the spherical anti-friction bodies are geometrically nearly identical.
It may be further preferred that the number of spherical anti-friction bodies is between 3-25, more preferable between 3-12, most preferable between 3-7, highest preferably exactly 5.
It may be preferred that the spherical anti-friction bodies are covered with an hydraulic oil or are even submersed in hydraulic oil, which further reduces the friction. Here it has become apparent that the viscosity of the oil in the range of 100-250 mm2/s at 20°C measured in accordance with ISO 3104 - 1976 is to be preferred. It has further been detected that an oil having a density between 0.7-0.95 g/cm3 show especial preferable friction reduction behaviour.

Method for manufacturing a door closer

The invention further comprises a method for manufacturing a door closer, especially a door closer according to this invention, comprising the steps of

a. Providing a first piston,
b. Providing a recess in the first piston,
c. Placing a spherical cam contact body in the recess,
d. Assembling the first piston into a cam drive of a door closer so that the spherical cam contact body is in contact with the cam surface of the door closers cam drive.

According to a preferred embodiment of the manufacturing method according to this invention, the method comprises the step of placing a plurality of freely movable spherical anti-friction bodies in the recess.
It is even more preferred that the method of manufacturing a door closer according to this invention comprises the step of placing a plurality of freely movable spherical anti-friction bodies in the recess before placing the spherical cam contact body in the recess.
Particular embodiments of the invention are now described based on the attached drawings. In the drawings,

Fig. 1a: perspective view on a piston arrangement according the prior art
Fig. 1b: cross-sectional view through the piston arrangement of Fig. 1a
Fig. 2: perspective view on the cam drive arrangement with a spherical cam contact body
Fig. 3: cross-sectional view on the cam drive arrangement with a spherical cam contact body
Fig. 4a: perspective view on a crimp like bearing in the first piston with spherical cam contact body outside the crimp like bearing
Fig. 4b: perspective view on a crimp like bearing in the first piston with spherical cam contact body positioned in the crimp like bearing
Fig. 4c: cross-sectional view on a crimp like bearing in the first piston with spherical cam contact body positioned in the crimp like bearing
Fig. 5a: perspective view on a piston with spherical anti-friction bodies to be positioned in the recess of the piston
Fig. 5b: perspective view on a piston with spherical anti-friction bodies positioned in the recess of the piston and a spherical cam contact body to be positioned in the recess of the piston
Fig. 5c: perspective view on a piston with spherical anti-friction bodies positioned in the recess of the piston and a spherical cam contact body positioned in the recess of the piston

Fig. 2 provides perspective view on the cam drive arrangement 5 with a spherical cam contact body 6.
The cam surface 3 is arranged in or at the spindle 2. By rotation of the spindle 2 the cam surface 3 rotates and pushes the spring biased piston 4 in a linear motion backwards or forward. This is indicated by the turning arrows RM and the linear arrows LM. Hence, the cam drive 5 transforms a rotational motion of the spindle 2 into a linear motion of the piston 4 and vice versa.
The spherical cam contact body 6 is positioned within the recess 7 of the piston 4. The spherical cam contact body 6 is in contact with the cam surface 3 as a not shown spring is pushing the piston 4 against the cam surface 3.
The bearing of the spherical cam contact body 6 in recess 7 of the piston 4 can be better seen in Fig. 3 which provides a cross sectional view through the arrangement known from Fig. 2.
The recess 7 in the piston 4 is of cylindrical shape. The diameter of the cylindrical recess 7 is slightly larger than the diameter of the spherical cam contact body 6 to ensure a defined positioning of the spherical cam contact body 7 in the cylindrical recess 7 as well as ensuring that no momentum is transmitted from the spherical contact body 6 to the piston 4. The spherical cam contact body has at least one point contact with the inner surface of the cylindrical recess 7. Depending on the accuracy of manufacture, it may also possible that the spherical cam contact body 6 has two point contacts or even a line contact. Nevertheless, due to friction minimisation aspects it is preferred that the spherical cam contact body shows only one point contact with the inner surface of the cylindrical recess 7.
At the bottom of the cylindrical recess 7 a plurality of spherical anti-friction bodies 9 is arranged. These spherical anti friction bodies 9 have point contacts to the inner surface of the cylindrical recess 7 as well as with the spherical cam contact body 7. Each spherical anti-friction body 9 has a point contact with the inner wall surface of the cylindrical recess 7 and the bottom surface of the cylindrical recess 7 as well as with the spherical cam contact body 7. With this arrangement, the friction in the piston arrangement is reduced to a minimum as well as the transmission of momentum from the cam surface 3 to the piston 4.
The spherical cam contact body 6 has further a point contact with the planar cam surface 3, hence the spherical cam contact body has at least four, preferably exactly four point contacts when arranged in the recess 7 of the piston 4 and in contact with the cam surface 3.
A bearing of the spherical contact body 6 alternatively to the bearing shown in Fig. 3 is provided with the Fig. 4a-c.
In this embodiment the piston 4 has a recess 7 in which a crimp like bearing 8 is foreseen for arranging the spherical cam contact body 6 in or on the piston 4. For crimping the spherical cam contact body 6 in the recess 7 four racks are formed radially inwards from the inner recess 7 surfaces which are configured to hold the spherical cam contact body 6 in the recess 7.
Fig. 5a-c show a method for manufacturing a door closer according to this invention. Fig. 5a-c show the piston 4 with a cylindrical recess 7. A plurality of spherical anti-friction bodies 9 is in a first step, which is shown in Fig. 5a, inserted into the cylindrical recess 7 and arranged at the bottom of the cylindrical recess 7. As shown in the Fig. 5a it is preferred to add 5 spherical anti-friction bodies 7 to the recess 7, whereby the spherical ant-friction bodies 9 have each a point contact with its direct neighbour anti-friction body, the inner surface of the cylindrical recess as well as with the bottom of the recess 7.
In the next step, which is shown in Fig. 5b, the spherical cam contact element 6 is added into the recess 7. The final arrangement of the spherical cam contact body 6 positioned on the spherical ant-friction bodies 9 in the recess 7 of the piston 4 is shown in Fig. 5c.

Claims

Door closer (1) comprising
- a housing

- a spindle (2) with a cam surface (3) whereby the spindle (2) extends through an opening of the housing,

- a first piston (4),

- wherein the spindle (2) is connected to the first piston (4) via a cam drive (5), wherein the cam drive (5) allows a translation of a longitudinal movement (LM) of the first piston (4) into a rotational movement (RM) of the spindle (2),

- whereby the cam surface (3) contacts the first piston (4),
characterised in that,
the first piston (4) comprises a spherical cam contact body (6) whose surface is in contact with the cam surface (3) of the door closers cam drive (5).
Door closer according to claim 1, characterized in that the cam surface (3) which is in contact with the spherical cam contact body (6) is planar.
Door closer according to any one of previous claims, characterized in that the spherical cam contact body (6) has a cam surface with surface hardness of at least 50 HRC and a cam surface with a surface finish of Ra < 0.3 .
Door closer according to any one of previous claims, characterized in that the cam surface (3) has a surface hardness of at least 50 HRC and a cam surface (3) with a surface roughness Rz < 6.3.
Door closer according to any one of previous claims, characterized in that the spherical cam contact body (6) is rotatable mounted in or to the first piston (4).
Door closer according to any one of previous claims, characterized in that the first piston (4) comprises a recess (7) for the bearing of the spherical cam contact body (6).
Door closer according to any one of previous claims, characterized in that the recess (7) is of cylindrical shape or of spherical shape.
Door closer according to any one of previous claims, characterized in that the spherical cam contact body (6) is mounted in the recess (7) of the first piston (4) by means of a crimp like bearing (8).
Door closer according to any one of previous claims, characterized in that the spherical cam contact body (6) is mounted in the recess (7) together with a plurality of freely movable spherical anti-friction bodies (9).
Door closer according to any one of previous claims, characterized in that the spherical anti-friction bodies (9) have a surface hardness of at least 50 HRC and surface finish of Ra < 0.3.
Door closer according to any one of previous claims, characterized in that the spherical anti-friction bodies (9) are geometrically nearly identical.
Door closer according to any one of previous claims, characterized in that the spherical anti-friction bodies (9) have a diameter which is 5-80% of the diameter of the spherical cam contact body (6).
Method for manufacturing a door closer, especially a door closer according to any of the previous claims, comprising the steps of
a. Providing a first piston (4),

b. Providing a recess (7) in the first piston (4),

c. Placing a spherical cam contact body (6) in the recess (7),

d. Assembling the first piston into a cam drive (5) of a door closer (1) so that the spherical cam contact body is in contact with the cam surface (3) of the door closers cam drive (5).
Method for manufacturing a door closer according to claim 13 comprising the step of placing a plurality of freely movable spherical anti-friction bodies (9) in the recess (7).
Method for manufacturing a door closer according to claim 13 or 14 comprising the step of placing a plurality of freely movable spherical anti-friction bodies (9) in the recess (7) before placing the spherical cam contact body (6) in the recess (7).