GB2223796A

GB2223796A - Door closer

Info

Publication number: GB2223796A
Application number: GB8816862A
Authority: GB
Inventors: Stephen James Harrison; Peter Edward Brown
Original assignee: Jebron Ltd
Current assignee: Jebron Ltd
Priority date: 1988-07-15
Filing date: 1988-07-15
Publication date: 1990-04-18
Also published as: GB2230050B; GB2230050A; GB8816862D0; GB8825642D0

Abstract

A door closer comprises a housing (10) containing a piston (22) acted on by a compression spring (21) and coupled to a pivoted arm (17) through a toothed element (23) rigid with the arm. The piston contains a row of rollers (25) which mesh with the element (23) and the transmission ratio between the arm and the spring is made to vary during pivoting of the arm by varying the distance (X) of the rollers from the axis (14) of the element along the row so as to give an increased torque at the end of the closing motion. The pitch of the rollers (25) may also vary along the row. The door closer may also incorporate fluid damping. <IMAGE>

Description

Title:"Door Closer" Description of Invention The present invention relates to a door closer of the kind comprising a housing, an arm mounted on the housing for pivoting relative thereto about a pivot axis, storing means disposed within the housing for storing energy when the arm is moved relative to the housing in a first direction and subsequently transferring the stored energy to the arm to force the arm to move in the opposite direction relative to the housing, a toothed element disposed in the housing and a driving element also disposed in the housing, wherein the toothed element is connected with the arm for turning therewith relative to the housing about the pivot axis, the driving element has formations enmeshed with the toothed element so that the driving element reciprocates in the housing when the toothed element turns about the pivot axis and wherein the driving element is operatively associated with the storing means for transmitting motion between the storing means and the toothed element.

A door closer of this kind is hereinafter described as being of the kind specified. A door closer of the kind specified usually comprises also a damper for restricting the speed at which the arm turns about the pivot axis.

The storing means of a door closer of the kind specified is usually in the form of a coiled compression spring. The force exerted by such a spring depends upon the degree of compression of the spring and therefore varies as the arm. moves relative to the housing. It is known to provide between the arm and a door to be controlled by the door closer a linkage which compensates, at least to some degree, for the variation in the force exerted on the arm as the spring is compressed and relaxed. However, such a linkage contributes significantly to the overall cost of the door closer.

According to a first aspect of the present invention, there is provided a door closer of the kind specified wherein the toothed element and the driving element are formed and arranged to transmit force from one to the other at a distance -from the pivot- axis-- which varies during the stroke of the driving element.

The torque exerted on the arm of a door closer in accordance with the first aspect of the invention, for a given pressure exerted by- the storing means, varies during pivoting of the arm. The torque required at different stages of pivoting of the arm can be achieved by suitable shaping of the toothed element and driving element.

The stroke of the driving element of a door closer in accordance with the first aspect of the invention can be restricted without unacceptable restriction of the range of movement of the arm or of the force exerted on the arm. Accordingly, a housing of only moderate length is required and this contributes to the attainment of a modest cost of manufacture of the door closer.

According to a second aspect of the invention, there is provided a door closer of the kind specified wherein the driving element comprises a number of rollers arranged in a row and wherein the teeth of the toothed element are arranged to enter gaps between adajcent rollers of the row and are formed to exert force on successive ones of the rollers as the driving element is moved by the toothed element. This arrangement also contributes to the attainment of a modest cost of manufacture of the door closer. Preferably, the first and second aspects of the invention are used in combination with one another.

An example of a door closer embodying both the first and second aspects of the present invention will now be described, with reference to the accompanying drawings, wherein FIGURE I shows a diagrammatic representation of a perspective view of the door closer, together with a part of a door controlled by the door closer; FIGURE 2 shows a toothed element and a driving element of the doo closer, as viewed in a direction along a pivot axis of the toothed element, the driving element being shown in cross-section in a plane perpendicular to that axis and these parts being represented in positions which -they- occupy when the driving element is part-way along its stroke; FIGURE 3 is a view similar to Figure 2 showing the parts when the driving element is at one end of its stroke; and FIGURE 4 is a cross-section in a plane containing the pivot axis.

The door closer comprises an elongated, hollow housing 10 having a substantially cylindrical bore 11. Opposite ends of the bore are closed by plugs, one of which is shown at 12. The external shape of the housing may be that of a rectangular prism and the housing may have apertures to receive screws or other fasteners for mounting the housing on the frame of a door.

A shaft 13 is mounted in the housing for rotation relative thereto about a pivot axis 14 which is perpendicular to the length of the housing and perpendicular to a pair of opposite, external faces of the housing. One end portion IS of the shaft lies in a bearing opening formed in the housing and an opposite end portion 16 of the shaft protrudes through a corresponding bearing opening at the opposite face of the housing. Suitable bushes or other bearing elements may be provided in the bearing openings. The protruding end portion ló of the shaft carries an arm 17 which is fixed on the end portion of the shaft by a screw 18.The portion of the shaft which receives the arm may have splines or flats for co-operation with complementary formations at the boundary of an aperture in the arm to restrain rotation of the arm relative to the shaft and to provide for mounting of the arm in alternative positions on the shaft. The arm 17 is connected in a known manner with a door 19 which is to be controlled by the door closer. For example, the arm may be pivotally connected at its end remote from the shaft 13 with a bracket 20 fixed to the door. If required, one or more additional elements may be interposed between the arm and the door.

Alternatively, the housing may be mounted directly on the door and the arm connected with the frame.

Energy storing means in the form of a coiled compression spring 21 is disposed in one end portion of the bore 11 and may bear against a seat provided on the housing 10 at the corresponding end of the bore or on a seat provided by the adjacent plug. An opposite end of the spring 21 is seated on a hollow piston 22 arranged for sliding along the bore II towards and away from the end plug 12. The interior of the housing 10 may contain oil or other fluid and the piston may be provided with valves and/or flow-restricting orifices to control flow of the fluid past the piston and thereby damp movement of the piston.

Transmission means is provided for transmitting motion between the spring 21 and the shaft 13. The transmission means includes a toothed element 23 carried on a mid-portion of the shaft 13 and a driving element 24 which is mounted inside the piston 22. The driving element is thereby guided for reciprocation relative to the housing 10 and the pivot axis 14. The element 23 has a part-annular row of teeth which mesh with formations of the driving element 24.

The formations of the driving element 24 are- a number of rollers, five in the example illustrated, arranged in a row extending generally along the housing 10. The rollers are carried by a common carrier 26. In the example illustrated, the carrier has the form of a channel with mutually parallel limbs at opposite sides of the channel. Bearing apertures for the rollers 25 are formed in the sides of the channel so that each roller extends across the interior of the channel at a position spaced from the base of the channel.

The base of the channel rests on the internal surface of the peripheral wall of the piston 22 and opposite ends of the channel abut respective end walls of the piston. The driving element is constrained by the toothed element 23 and the shaft 13 against movement towards the pivot axis 14 so that the base of the channel is held against the peripheral wall of the piston. This wall may be provided with internal ribs adjacent to opposite sides of the channel to prevent movement of the channel relative to the piston in directions around the circumference of the piston. Since the driving element is trapped in a fixed position inside the piston, it may be unnecessary to secure the driving element otherwise to the piston. However, the driving element may be brazed or otherwise secured to the piston, if required.

Whilst a rigid carrier 26 which is common to all of the rollers 25 has been shown in the drawing, the rollers may alternatively be connected to one another by chainlinks to form a length of chain which is secured in the piston.

As the piston 22 reciprocates in the housing 10, the rollers 25 travel past the pivot axis 14. The shortest spacing from the axis attained by each of the rollers varies from one roller to another. In the example illustrated, the rollers 25a, 25b and 25c are spaced by the same distance from the base of the channel of the driving element 24. The roller 25d lies somewhat nearer to the base of the channel and the roller 25e lies even nearer to the base of the channel. Accordingly, when the driving element is moved past the pi zot axis, the roller 25c approaches that axis more closely than does the roller 25d.

The pitch of the rollers 25 also varies along the row. The spacing between respective axes of the rollers 25a and 25b is equal to the spacing between the axes of the rollers 25b and 25c. The axis of the roller 25d is spaced somewhat further from the axis of the roller 25c and the axis of the roller 25e is spaced even further from the axis of the roller 25d.

The teeth of the toothed element 23 are arranged to enter the gaps between respective pairs of adjacent rollers 25 and are formed to exert force on successive ones of the rollers as the driving element 24 is moved along the housing 10 by turning of the toothed element 23. The position at which force is transmitted between the driving element and the toothed element varies during the stroke of the driving element and lies further from the pivot axis 14 at one end of that stroke than is the case when the driving element is at the opposite end of its stroke.

Figure 2 illustrates the relative positions of the toothed element and driving element when the latter is part-way through its stroke. If the driving element 24 is being moved by the spring 21, the roller 25d exerts torque on the toothed element at a position spaced from the axis 14 in a direction perpendicular to the direction of movement of the roller 25d which is represented by the value X in Figure 2. As shown in Figure 3, when the spring is almost fully extended, the roller 25e exerts force on the toothed element at a position spaced from the axis 14 in a direction perpendicular to the direction of the movement of the roller which is represented by the value Y in Figure 3. The value Y is greater than the value X. As the spring becomes fully extended, the force it exerts on the driving element 24 falls.

However, this decrease in force can be compensated for by appropriate selection of the vaues X and Y. The value of Y moy be sufficiently large to ensure that the torque exerted on the toothed element 23 as the spring becomes fully extended exceeds the torque exerted when the spring is only partly extended. An increase in the applied torque as the spring becomes fully extended is useful to overcome the resistance to final closing of a door which may arise from air pressure on the door and/or the operation of a latch.

When the spring 21 is being compressed by movement of the arm 17 during opening of the door, the rate of linear displacement of the driving element 24 with respect to angular movement of the arm varies during that movement. As the spring is compressed further, the linear displacement of the driving element which results from each unit of rotation of the toothed element 23 becomes less. The transmission ratio provided by the transmission means and therefore the mechanical advantage vary during the stroke of the driving element 24.

The particular arrangement illustrated provides a constant transmission ratio over that part of the stroke during which force is applied to and applied by the rollers 25a, 25b and 25c, since these rollers are all spaced by the same distance from the base of the channel of the driving element. The relative positions of the rollers may be varied from that illustrated to provide variation of the transmission ratio in some other manner.

The toothed element-23: may be fixed on the shift 13 by brazing.

Alternatively, rotation of the toothed-element relative to the shaft may berestrained by means of a key. The shaft 13 is preferably formed in at least two parts which are assembled together to trap-the toothed element 23. It will be noted that the portion of the shaft on which the toothed element 23 is carried has a diameter which is considerably less than the diameter of the end portions of the shaft. This is advantageous, because the end portion 16 is required to have splines or other formations for co-operation with the arm 17 and is also required to have a threaded bore to receive the screw 18. On the other hand, the opening of the toothed element 23 is required to have a fairly small diameter, since the root of at least one of the teeth is near to the axis 14.The rollers 25a, 25b and 25c are required to approach the axis 14 to within a distance which is less than the radius of the end portion 16 of the shaft. The side walls of the channel of the driving element are required to approach even closer to the axis 14 and the shaft 13 is therefore required to have at opposite sides of the toothed element 23 necks of relatively small diameter to provide clearance for the side walls of the channel.

The small diameter portion of the shaft 13 may be formed as a stub on one of the end portions, the free-end of the stub being received in a socket in the opposite end portion of the shaft. Alternatively, the small diameter portion of the shaft may be formed separately from the end portions, each end portion having a respective socket to receive a corresponding end of the small diameter portion of the shaft. In either case, the toothed element 23 would be fitted on to the small diameter portion of the shaft before the several portions of the shaft are assembled together.

The toothed element 23 is conveniently formed by stamping, forging, casting or by drawing a long length of metal having the appropriate crosssection and severing a number of toothed elements from the length.

The rollers 25 are free to turn about their own axes in the carrier 26.

As the teeth of the element 23 move into and out of mesh with the rollers, the latter roll on the teeth. This minimises wear of both the teeth and the rollers. The fit of the rollers between the teeth of the element 23 is such that, at all positions of the driving element 24, turning of the element 23 in either direction about the axis 14 is necessarily accompanied by longitudinal movement of the driving element and that the driving element cannot undergo significant longitudinal movement without turning of the toothed element. The angular position of the arm 17 is therefore controlled throughout its movement.

The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims

CLAIMS:

1. A doorcloser of the kind specified wherein the toothed element and the driving element are formed and arranged to transmit force from one to the other at a distance from the pivot axis which varies during the stroke of the driving element.

2. A doorcloser according to Claim I wherein the driving element comprises a number of rollers arranged in a row and wherein the teeth of the toothed element are arranged to enter gaps between adjacent rollers and are formed to exert force on successive ones of the rollers as the driving element is moved by the toothed element.

3. A doorcloser of the kind specified wherein the driving element comprises a number of rollers arranged in a row and wherein the teeth of the toothed element are arranged to enter gaps between adjacent rollers of the row and are formed to exert force on successive ones of the rollers as the driving element is moved by the toothed element.

4. A doorcloser according to Claim 2 or Claim 3 wherein the row is non rectilinear.

5. A doorcloser according to Claim 4 wherein the row includes a rectilinear portion.

6. A doorcloser according to any one of Claims 2 to 5 wherein the rollers are carried by a common, substantially rigid carrier.

7. A doorcloser according to Claim 6 wherein the carrier has the form of a channel and wherein the teeth of the toothed element penetrate into the channel as they move into mesh with the rollers.

8. A doorcloser according to any one of Claims 2 to 7 wherein the pitch of the rollers varies along the row.

9. A doorcloser according to Claim 6 or Claim 7 further comprising a shaft which connects the toothed element with the arm and wherein the carrier approaches the pivot axis to a distance which is less than the diameter of the shaft adjacent to the carrier, the shaft having an annular shoulder which faces towards and overlaps with the carrier.

10. A doorcloser of the kind specified wherein the toothed element and the driving element are substantially as herein described with reference to and as illustrated in the accompanying drawings.

II. Any novel feature or novel combination of features disclosed herein or in the accompanying drawings.