GB2603819A

GB2603819A - Hoist with safety function

Info

Publication number: GB2603819A
Application number: GB2105012.5A
Authority: GB
Inventors: Brocklehurst Terence; Penny Robin
Original assignee: PENNY HYDRAULICS Ltd
Current assignee: PENNY HYDRAULICS Ltd
Priority date: 2021-04-08
Filing date: 2021-04-08
Publication date: 2022-08-17
Anticipated expiration: 2041-04-08
Also published as: GB202105012D0; GB2603819B

Abstract

A hoist 100 for a load includes a drum and a motor (102, 106 fig.1) whereby drive is transferred to the drum via a mechanical interface arrangement. The hoist includes a brake mechanism having an array of teeth 124, which may be on a flange 122, and a brake block 132 that engages with the teeth. The teeth may be separated by a land region 130 that may be 50% or more of the width of the tooth base. The brake block may have first and second braking surfaces 144, 146 to engage with the tip of the tooth at 148 and may have third and fourth braking surfaces 154, 156 to engage flange 122 between a pair of teeth.

Description

Hoist with safety function

FIELD

The present disclosure relates to a hoist haying a safety function.

BACKGROUND

A hoist is a device used for raising or lowering a load. Conventional hoists have rotating a drum around which rope can be wound and unwound.

Typically, a motor and gearbox arrangement is used to rotate the drum, for controlled movement of the load in a desired direction. Such systems usually include a mechanical interface between the motor/gearbox arrangement and the shaft with which the drum rotates. However, should there be a failure within the mechanical interface, the drum will be free to rotate and the load may fall under gravity. This presents a health and safety risk, as well as a risk to the integrity of the hoist's components (e.g. if shocked through jolting as the load falls or strikes the ground or other objects).

It is an object of the present disclosure to provide a hoist with a safety function for arresting a falling load, particularly, but not exclusively, if the hoist is at rest.

SUMMARY

According to a first aspect of the invention, there is provided a hoist for use in raising or lowering a load, the hoist comprising a drum which is operable to rotate in first and second directions for respective lowering or raising of a load, wherein the drum is operable to rotate in a controlled manner under output drive from a motor, and wherein drive is transferred to the drum via a mechanical interface arrangement; wherein the hoist includes a brake mechanism for preventing undesired rotation of the drum, wherein the brake mechanism comprises an array of teeth arranged for rotation with the drum, and a brake block for engagement with the teeth in order to prevent rotation of the drum.

Advantageously, if there is a failure of the mechanical interface between the motor and the drum, the drum is not free to rotate in an uncontrolled manner, and so any load supported by the hoist prior to failure is not free to fall under gravity. This overcomes conventional health and safety issues, and also prevents or reduces maintenance issues that might otherwise occur if the hoist's components were to be shocked through jolting as the load fell or struck the ground or other objects.

In exemplary embodiments, the winch drum includes a flange and the teeth are provided in a spaced array about the circumference of the flange.

In exemplary embodiments, the flange is provided at one end of the drum; optionally integral with the drum.

In exemplary embodiments, the drum defines a barrel having an outer diameter around which a rope or chain is intended to be wound, and wherein the flange has a greater diameter than the barrel.

In exemplary embodiments, the flange defines a wall for limiting movement of a rope or chain being wound on the drum, in use.

In exemplary embodiments, the flange projects in a direction perpendicular to the longitudinal axis of the drum.

In exemplary embodiments, the teeth project in the same plane as the flange (i.e. perpendicular to the longitudinal axis of the drum).

In exemplary embodiments, each tooth has an inverted V-shaped profile.

In exemplary embodiments, the teeth define a uniform series of peaks and troughs.

In exemplary embodiments, the teeth are spaced apart from one another.

In exemplary embodiments, the teeth are separated by a land region.

In exemplary embodiments, each land region has a length of at least 50% of the width of the base of each tooth.

In exemplary embodiments, the hoist includes an electronic control system for controlling movement of the brake block between the stowed position and the deployed position.

In exemplary embodiments, the control system includes a solenoid in communication with the brake block, wherein the brake block is retracted or held in the stowed position when the solenoid is energised.

In exemplary embodiments, a spring is provided in communication with the brake block, for urging the brake block to the deployed position.

In exemplary embodiments, the brake block is intended for use as a park brake, wherein the hoist is configured to move the brake block to the deployed position when the hoist is at rest.

In exemplary embodiments, the brake block is intended for use as an emergency brake, wherein the hoist is configured to move the brake block to the deployed position in the event of a failure at the mechanical interface arrangement, or if the drum is rotating at undesired speed.

In exemplary embodiments, the brake block includes first and second brake surfaces, either one of which is intended to arrest rotation of the drum by abutment with a leading edge of one of the teeth when the brake block is in the deployed position.

In exemplary embodiments, the first and second brake surfaces cooperate to define a generally Z-shaped profile, in which the first brake surface is the lower arm of the 7-shaped profile, and the second brake surface is the upper arm of the 7-shaped profile.

In exemplary embodiments, the first and second brake surfaces are interconnected by a third surface; optionally, a third brake surface arranged to prevent counter rotation of a tooth in engagement with the first brake surface; optionally, wherein the first and third brake surfaces define a notch in the brake block; optionally, wherein the notch is complimentary to the profile of each tooth.

In exemplary embodiments, the second brake surface is intended to be horizontal in use.

In exemplary embodiments, the 7-shaped profile is irregular, wherein the first brake surface is not parallel with the second brake surface; optionally, wherein the first brake surface slopes downward from parallel relative to the second brake surface, such that the free end of the first brake surface is elevated relative to the opposite end of the first brake surface when the second brake surface is horizontal.

In exemplary embodiments, the hoist is configured such that the angle between the first brake surface and the second brake surface is half of the angle between the pitch of the teeth.

In exemplary embodiments, the brake block includes a fourth brake surface, arranged for abutment with the trailing edge of a second tooth, if the leading edge of a first tooth is in abutment with the third brake surface; optionally, when the second tooth is one peak more rotationally advanced in the downward direction than the first tooth; optionally, wherein the fourth brake surface serves to prevent counter rotation of the drum when the leading edge of a first tooth is in abutment with the second brake surface; optionally, wherein the fourth brake surface is parallel with the third brake surface; optionally, wherein the fourth brake surface extends downward from the elevated end of the first brake surface.

In exemplary embodiments, the teeth have an asymmetrical profile; optionally, so as to define the profile of an irregular non-right angle triangle; optionally, wherein each tooth has a peak and opposing edges sloping from the peak, wherein one edge is longer than the other.

In exemplary embodiments, the profile of each tooth is configured such that the leading edge of the tooth profile in the downward rotational direction is horizontal if the rotational position of the teeth at the moment that the brake block is such that one of the teeth is blocked against rotation by the third brake surface.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will now be described with reference to the accompanying drawings, in which: Figure 1 is a schematic plan view of a hoist; Figure 2 is a side view of the hoist shown in Figure 1; Figure 3 is a cross-sectional view along the lines A-A of Figure 2, showing the brake mechanism in an inactive state; Figure 4 is similar to Figure 3, but shows the brake mechanism in an active state, with the teeth in a first mode of braking engagement; Figure 5 is similar to Figure 3, but shows the teeth in a second mode of braking engagement.

DETAILED DESCRIPTION OF EMBODIMENTS

Referring firstly to Figure 1, a hoist is shown generally at 100, for use in raising or lowering a load. The hoist 100 has a drum 102 which is operable to rotate in first and second directions for respective raising or lowering of a load.

The drum 102 is mounted for rotation with a shaft 104, and is operable to rotate in a controlled manner under drive from a motor 106. In this embodiment, drive from the motor transfers through a gearbox which is mounted in a housing 108 (although a gear box may not be necessary in some embodiments). Drive for the drum 102 is transferred to the shaft via a mechanical interface arrangement between the motor 106 and the shaft 104. The mechanical interface arrangement is not visible in the drawings but is provided inside the housing 108 in this embodiment.

A first end 112 of the shaft 104 rotates in a bearing (not shown) in or adjacent the mechanical interface arrangement. A second end 114 of the shaft 104 rotates in a bearing 116 in a bearing retainer plate 118 spaced from the mechanical interface arrangement.

The drum 102 defines a barrel 120 having an outer surface around which a rope is intended to be wound. As can be seen, the barrel 120 is arranged between the mechanical interface arrangement and the bearing retainer plate 118.

The mechanical interface arrangement and the bearing retainer plate 118 are supported on a common base 121.

As can be seen in Figures 1 and 2, the drum 102 includes a flange 122 provided at one end, adjacent the bearing retainer plate 118 in this embodiment. The flange 122 has a greater outer diameter than the barrel 120, and projects in a direction perpendicular to the longitudinal axis of the drum 102.

As can be seen clearly from Figure 3, a plurality of teeth 124 are provided in a spaced array about the circumference of the flange 122. The teeth 124 project in the same plane as the flange 122 (i.e. perpendicular to the longitudinal axis of the drum 102).

The array of teeth 124 defines a uniform series of peaks and troughs indicated generally at 126, 128, respectively.

In this embodiment, each tooth 124 has an inverted V-shaped profile.

In this embodiment, the teeth 124 are separated from one another by a land region 130, which has a length of at least 50% of the width w at the base of each tooth 124. Each land region 130 extends in a direction generally tangential to the axis of rotation of the drum 102.

The teeth 124 form part of a brake mechanism for selectively preventing rotation of the drum 102. The brake mechanism further includes a brake block 132 for engagement with the teeth 124, so as to be able to prevent rotation of the flange 122 and, hence, prevent rotation of the drum 102.

The brake block 132 is moveable from an inactive or stowed position to an active or deployed position. The flange 122 and drum 102 are free to rotate when the brake block 132 is in the stowed position. However, as will be described in more detail below, rotation of the flange 122 and drum 102 is prevented by the brake block 132, if the brake block is in the deployed position.

The hoist 100 includes an electronic control system, indicated generally at 134 in Figures 1 to 3, for controlling movement of the brake block 132 between the stowed position and the deployed position.

In this embodiment, the control system 134 includes a solenoid 136 which is in communication with the brake block 132, such that the brake block is retracted or held in the stowed position when the solenoid is energised.

A spring 138 is provided in communication with the brake block 132, for urging the brake block 132 to the deployed position, e.g. when the solenoid 136 is de-energised. The biasing force from the spring 138 is not capable of overcoming the retracting force of the energised solenoid 136.

In exemplary embodiments, the brake mechanism is intended for use as a park brake.

That is to say, the control system 134 is configured to de-energise the solenoid, so as to permit the brake block to move to its deployed position when the hoist 100 is at rest.

For example, a rotary limit switch 140 can be used to monitor the rotation of the drum 102 and/or the active state motor 106, to establish whether the hoist is at rest or operating normally.

It will be understood that the control system 134 includes a controller (not shown), e.g. a microcontroller unit (MCU), for monitoring all input signals and controlling all output signals for operation of the brake mechanism. The controller may be arranged in communication with the motor 106, e.g. for monitoring the state of the motor inverter, to indicate the operating state of the motor 106.

In other embodiments, the brake mechanism can be used to provide an emergency brake function, e.g. to de-energise the solenoid 136, so as to permit the brake block 132 to move to the deployed position, if the control system determines that there has been a failure at the mechanical interface arrangement, and/or if the control system determines that the drum 102 is rotating at undesired speed (e.g. when compared to the motor speed at normal operating conditions).

In the illustrated embodiment, a free end 142 of the brake block 132 includes first and second brake surfaces 144, 146. The brake surfaces 144, 146 cooperate to define a notch 148. The shape of the notch 148 is configured to receive at least the peak of a tooth 124, such that a proportion of the first and second brake surfaces 144, 146 are immediately adjacent respective sloping edges 150, 152 of the inverted V-shaped profile of the tooth 124 (i.e., the forward rotation and backward rotation edges of the tooth 124). This serves to provide double engagement of a tooth 124, helping to lock the drum 102 against rotation, and is shown in Figure 4.

In exemplary embodiments of the kind shown in Figures 3 to 5, the teeth 124 have an asymmetrical profile, so as to define an irregular non-right angle triangle. That is to say, one of the sloping sides 150 of each tooth 124 is longer than the other sloping side 152.

Accordingly, each land region 130 does not extend in a truly tangential direction, but is slightly angled away from a truly tangential direction. This has been found to provide further improved resistance to rotation of the drum 102 under load than merely using forward and rearward engagement of the teeth 124.

It will be understood that double engagement of the kind shown in Figure 4 is dependent on the rotational position of the teeth 124 at the moment that the brake block 132 is deployed.

The brake block 132 includes a third brake surface 154, which is arranged to be horizontal in use (i.e. parallel with the plane of the common base 121). In the illustrated embodiment, the third brake surface 154 is an upper surface of the brake block 132. Moreover, the profile of each tooth 124 is configured such that the leading edge of the tooth profile in the downward rotational direction (i.e. sloping edge 144) would also be horizontal in use (i.e. parallel with the plane of the third brake surface 154) if the rotational position of the teeth 124 at the moment that the brake block 132 is deployed meant that a tooth 124 would be blocked against rotation by the third brake surface 154 of the brake block 132, in abutment with the third brake surface 154.

The brake block 132 is configured such that the first, second and third brake surfaces 144, 146, 154 cooperate to define a generally Z-shaped profile, in which the third brake surface 154 is the upper arm of the Z-shaped profile, the first brake surface 144 is the lower arm of the Z-shaped profile, and the second brake surface 146 is the connecting arm of the Z-shaped profile. As stated above, the third brake surface 144 is intended to be horizontal in use. However, the Z-shaped profile is irregular, since the first brake surface 144 is not parallel with the third brake surface 154. Rather the first brake surface 144 slopes downward from parallel relative to the third brake surface 154, such that the free end of the first brake surface 144 is elevated relative to the opposite end of the first brake surface 144.

In the illustrated embodiment, the brake block 132 includes a fourth brake surface 156, which arranged for abutment with the trailing edge 152 of a second tooth 124, if the leading edge 150 of a first tooth 124 is in abutment with the third brake surface 154 (when the second tooth 124 is one peak more rotationally advanced in the downward direction than the first tooth 124). The fourth brake surface 156 therefore serves to prevent counter rotation of the drum 102 in a similar way to the second brake surface 146, albeit on a separate tooth 124.

The fourth brake surface 156 is parallel with the second brake surface 146, and extends downward from the elevated end of the first brake surface 144.

It will be understood that braking is possible using only the first and third brake surfaces 144, 154, for blocking rotation of the leading edge 150 of a tooth 124. However, the use of the second and/or fourth brake surfaces 146, 156 provides additional resistance to rotation.

The hoist 100 is configured such that the angle between the first brake surface 144 and the third brake surface 154 is half of the angle between the pitch of the teeth 124 (i.e. between peak to peak). In the illustrated embodiment, the angles are 12 degrees and 24 degrees respectively.

Such a configuration ensures brake engagement points at every half pitch rotation of the teeth 124, such that braking can be achieved with minimal rotation of the drum 102, and wherein double engagement is possible at each half pitch rotation in embodiments where the second and fourth brake surfaces 146, 156 are configured to be complimentary to the trailing edge 152 of the teeth 124.

Claims

CLAIMS1. A hoist for use in raising or lowering a load, the hoist comprising a drum which is operable to rotate in first and second directions for respective lowering or raising of a load, wherein the drum is operable to rotate in a controlled manner under output drive from a motor, and wherein drive is transferred to the drum via a mechanical interface arrangement; wherein the hoist includes a brake mechanism for preventing undesired rotation of the drum, wherein the brake mechanism comprises an array of teeth arranged for rotation with the drum, and a brake block for engagement with the teeth in order to prevent rotation of the drum.
2. A hoist according to claim 1, wherein the winch drum includes a flange and the teeth are provided in a spaced array about the circumference of the flange.
3. A hoist according to claim 2, wherein the flange is provided at one end of the drum; optionally, integral with the drum.
4. A hoist according to claim 2 or claim 3, wherein the drum defines a barrel having an outer diameter around which a rope is intended to be wound, and wherein the flange has a greater diameter than the barrel.
5. A hoist according to any of claims 2 to 4, wherein the flange defines a wall for limiting movement of a rope being wound on the drum, in use.
6. A hoist according to any of claims 2 to 5, wherein the flange projects in a direction perpendicular to the longitudinal axis of the drum.
7. A hoist according to any of claims 2 to 6, wherein the teeth project in the same plane as the flange (i.e. perpendicular to the longitudinal axis of the drum).
8. A hoist according to any preceding claim, wherein each tooth has an inverted V-shaped profile.
9. A hoist according to any preceding claim, wherein the teeth define a uniform series of peaks and troughs.
10. A hoist according to any preceding claim, wherein the teeth are spaced apart from one another.
11. A hoist according to any preceding claim, wherein the teeth are separated by a land region; optionally, wherein each land region has a length of at least 50% of the width of the base of each tooth.
12. A hoist according to any preceding claim, wherein the hoist includes an electronic control system for controlling movement of the brake block between a stowed position and a deployed position.
13. A hoist according to claim 12, wherein the control system includes a solenoid in communication with the brake block, wherein the brake block is retracted or held in the stowed position when the solenoid is energised.
14. A hoist according to any preceding claim, wherein a spring is provided in communication with the brake block, for urging the brake block to a deployed position.
15. A hoist according to any preceding claim, wherein the brake block is intended for use as a park brake, wherein the hoist is configured to move the brake block to a deployed position when the hoist is at rest.
16. A hoist according to any preceding claim, wherein the brake block is intended for use as an emergency brake, wherein the hoist is configured to move the brake block to a deployed position in the event of a failure at the mechanical interface arrangement, or if the drum is rotating at undesired speed.
17. A hoist according to any preceding claim, wherein the brake block includes first and second brake surfaces, either one of which is intended to arrest rotation of the drum by abutment with a leading edge of one of the teeth when the brake block is in a deployed position.
18. A hoist according to claim 17, wherein the first and second brake surfaces cooperate to define a generally Z-shaped profile, in which the first brake surface is the lower arm of the Z-shaped profile, and the second brake surface is the upper arm of the Z-shaped profile.
19. A hoist according to claim 17 or claim 18, wherein the first and second brake surfaces are interconnected by a third surface; optionally, a third brake surface arranged to prevent counter rotation of a tooth in engagement with the first brake surface; optionally, wherein the first and third brake surfaces define a notch in the brake block; optionally, wherein the notch is complimentary to the profile of each tooth.
20. A hoist according to any of claims 17 to 19, wherein the second brake surface is intended to be horizontal in use.
21. A hoist according to claim 18, wherein the 7-shaped profile is irregular, wherein the first brake surface is not parallel with the second brake surface; optionally, wherein the first brake surface slopes downward from parallel relative to the second brake surface, such that the free end of the first brake surface is elevated relative to the opposite end of the first brake surface when the second brake surface is horizontal.
22. A hoist according to any of claims 17 to 21, wherein the hoist is configured such that the angle between the first brake surface and the second brake surface is half of the angle between the pitch of the teeth.
23. A hoist according to claim 19, wherein the brake block includes a fourth brake surface, arranged for abutment with the trailing edge of a second tooth, if the leading edge of a first tooth is in abutment with the third brake surface; optionally, when the second tooth is one peak more rotationally advanced in the downward direction than the first tooth; optionally, wherein the fourth brake surface serves to prevent counter rotation of the drum when the leading edge of a first tooth is in abutment with the second brake surface; optionally, wherein the fourth brake surface is parallel with the third brake surface; optionally, wherein the fourth brake surface extends downward from the elevated end of the first brake surface.
24. A hoist according to any preceding claim, wherein the teeth have an asymmetrical profile; optionally, so as to define the profile of an irregular non-right angle triangle; optionally, wherein each tooth has a peak and opposing edges sloping from the peak, wherein one edge is longer than the other.
25. A hoist according to claim 19, wherein the profile of each tooth is configured such that the leading edge of the tooth profile in the downward rotational direction is horizontal if the rotational position of the teeth at the moment that the brake block is deployed is such that one of the teeth is blocked against rotation by the third brake surface.