GB2164103A - Torque limiter coupling - Google Patents

Abstract

A friction plate torque limiter, comprises a hub 1, rotatably connected to a plate 3 via a bearing 4, the plate being mounted between friction plates 2,6, which are subject to an axial force, transmitted by a thrust ring 8 which is slidably connected to the hub 1, provided by springs 11, 12 which are restrained by an adjusting nut 10. The nut 10 is engaged by screws 9 which co- operate with retracting levers 7, which are driven by members 5, attached to the plate 3, where the friction plates slip. In this way the slip of the plates with respect to the hub causes axial movement of the thrust ring 8, removing the axial force from the friction plates and permitting the torque limiter to slip at a reduced torque and thus a reduced heat dissipation. <IMAGE>

Description

SpECIFICATION Torque limiter coupling This invention relates to a torque limiter coupling.

There already exists a wide range of torque limiter couplings of the friction plate type, where torque or power is transmitted from a gear or sprocket to a shaft by the use of clutch plates. The clutch plates are subjected to an axial force which enables them to develop a driving force tangential to their surface. However, when these devices are used as torque limiters, there are occasions when the output (load) device ceases to rotate, while the input (motor) device continues to rotate. As a consequence a large proportion of the power delivered by the motor is dissipated in the torque limiter resulting in a high rate of temperature rise. The resulting high temperatures can cause failure of the torque limiter.

According to the present invention there is provided a friction plate type torque limiter, consisting of a hub, rotatably connected to a drive plate via a bearing, the drive plate being mounted between friction plates, which are subject to an axial force, (transmitted by a thrust ring which is slidably connected to the hub), provided by springs which are restrained by an adjusting nut, which is provided with threaded features which co-operate with retracting levers, which are driven by features attached to the drive plate. In this way the slip of the drive plate with respect to the hub causes axial movement of the thrust ring, removing the axial force from the friction plates and permitting the torque limiter to slip at a reduced torque and thus a reduced heat dissipation.

A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawing in which Fig. 1 shows an outside view of the assembly from an oblique angle. Fig. 2 shows a radial section through the shaft centre line.

Fig. 3 shows an end view of the assembly.

Referring to Fig. 2 the shaft S is connected to the driving hub 1 in such a way as to permit the transmission of torque or power from one to the other. A keyed connection is shown (in Fig. 3) but a wide variety of torque transmitting means are possible.

There is provided, rotatably connected to the hub 1 via a bearing 4, a plate 3. Either plain or rolling element bearings may be used depending upon the requirements of the particular design. A plate of duplex chainwheel form is shown but various other means of transmitting the output power may be required to co-operate with the neighbouring machinery (single or multiple chainwheels, toothed gears, pulleys or shaft coupling types could be used).

In contact with both faces of the plate there are provided friction discs 2, 6.

There is provided a thrust ring 8, which is slidably connected to but constrained to rotate with the hub 1, which exerts an axial force upon the plate and the friction discs. This axial force is produced by the compression of springs 11, 12 forced into compression by the adjusting nut 10.

In addition there are driving features 5 attached to the plate 3. When this plate slips with respect to the thrust ring 8 these driving features 5 engage with the operating lever 7 causing the releasing screw 9 to rotate, (see also Figs. 1, 3). The releasing screw 9 has a pattern of helical grooves on its surface which co-operate with corresponding helical grooves in the adjusting nut 10. As a result of this cooperation the rotation of the releasing screw 9 causes the thrust ring 8 to be drawn towards the adjusting nut 10. This movement creates axial clearance between the plate 3 and the friction discs 2,6 because of the relative axial movement between the hub 1 and the thrust ring 8.

Two sets of operating levers 7 and releasing screws 9 may be provided in order that the coupling may be responsive to overloads in either direction.

1. A torque limiter coupling comprising a hub, rotatably connected to a drive plate via a bearing, the drive plate being mounted between friction plates, which are subject to an axial force, (transmitted by a thrust ring which is slidably connected to the hub), provided by springs which are restrained by an adjusting nut, which is provided with threaded features which co-operate with retracting levers, which are driven by features attached to the drive plate.

2. A torque limiter coupling as claimed in claim 1, wherein the slip of the drive plate with respect to the hub causes axial movement of the thrust ring, removing the axial force from the friction plates and permitting the torque limiter to slip at a reduced torque and thus a reduced heat dissipation.

3. A torque limiter coupling substantially as described with reference to the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (3)

**WARNING** start of CLMS field may overlap end of DESC **. SpECIFICATION Torque limiter coupling This invention relates to a torque limiter coupling. There already exists a wide range of torque limiter couplings of the friction plate type, where torque or power is transmitted from a gear or sprocket to a shaft by the use of clutch plates. The clutch plates are subjected to an axial force which enables them to develop a driving force tangential to their surface. However, when these devices are used as torque limiters, there are occasions when the output (load) device ceases to rotate, while the input (motor) device continues to rotate. As a consequence a large proportion of the power delivered by the motor is dissipated in the torque limiter resulting in a high rate of temperature rise. The resulting high temperatures can cause failure of the torque limiter. According to the present invention there is provided a friction plate type torque limiter, consisting of a hub, rotatably connected to a drive plate via a bearing, the drive plate being mounted between friction plates, which are subject to an axial force, (transmitted by a thrust ring which is slidably connected to the hub), provided by springs which are restrained by an adjusting nut, which is provided with threaded features which co-operate with retracting levers, which are driven by features attached to the drive plate. In this way the slip of the drive plate with respect to the hub causes axial movement of the thrust ring, removing the axial force from the friction plates and permitting the torque limiter to slip at a reduced torque and thus a reduced heat dissipation. A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawing in which Fig. 1 shows an outside view of the assembly from an oblique angle. Fig. 2 shows a radial section through the shaft centre line. Fig. 3 shows an end view of the assembly. Referring to Fig. 2 the shaft S is connected to the driving hub 1 in such a way as to permit the transmission of torque or power from one to the other. A keyed connection is shown (in Fig. 3) but a wide variety of torque transmitting means are possible. There is provided, rotatably connected to the hub 1 via a bearing 4, a plate 3. Either plain or rolling element bearings may be used depending upon the requirements of the particular design. A plate of duplex chainwheel form is shown but various other means of transmitting the output power may be required to co-operate with the neighbouring machinery (single or multiple chainwheels, toothed gears, pulleys or shaft coupling types could be used). In contact with both faces of the plate there are provided friction discs 2, 6. There is provided a thrust ring 8, which is slidably connected to but constrained to rotate with the hub 1, which exerts an axial force upon the plate and the friction discs. This axial force is produced by the compression of springs 11, 12 forced into compression by the adjusting nut 10. In addition there are driving features 5 attached to the plate 3. When this plate slips with respect to the thrust ring 8 these driving features 5 engage with the operating lever 7 causing the releasing screw 9 to rotate, (see also Figs. 1, 3). The releasing screw 9 has a pattern of helical grooves on its surface which co-operate with corresponding helical grooves in the adjusting nut 10. As a result of this cooperation the rotation of the releasing screw 9 causes the thrust ring 8 to be drawn towards the adjusting nut 10. This movement creates axial clearance between the plate 3 and the friction discs 2,6 because of the relative axial movement between the hub 1 and the thrust ring 8. Two sets of operating levers 7 and releasing screws 9 may be provided in order that the coupling may be responsive to overloads in either direction. CLAIMS

1. A torque limiter coupling comprising a hub, rotatably connected to a drive plate via a bearing, the drive plate being mounted between friction plates, which are subject to an axial force, (transmitted by a thrust ring which is slidably connected to the hub), provided by springs which are restrained by an adjusting nut, which is provided with threaded features which co-operate with retracting levers, which are driven by features attached to the drive plate.

2. A torque limiter coupling as claimed in claim 1, wherein the slip of the drive plate with respect to the hub causes axial movement of the thrust ring, removing the axial force from the friction plates and permitting the torque limiter to slip at a reduced torque and thus a reduced heat dissipation.

3. A torque limiter coupling substantially as described with reference to the accompanying drawings.