Patent Application
20210284510
The present invention relates to a brake system. Specifically, the present invention is a secondary braking system for use with a hoist.
The use of hoists for lifting and lowering items is well known. Known in the art are several mechanisms used in braking for a hoist. Some braking mechanisms apply friction directly to the hoist drum to slow/stop rotation of the drum. Another means of braking involves applying friction to the drive shaft of the hoist to slow/stop rotation. Braking of hoists may also be accomplished by applying friction directly to the hoist line.
A drawback of prior art hoist brakes is the need for early engagement of the brake device to stop the hoist line at a desired location. Another drawback of prior art hoist brakes is the need to manually adjust the brake system over time due to wear and alignment issues due to vibration and stresses on the hoist. Many prior art hoist brakes do not include built-in failsafe structures and require secondary emergency braking systems to deal with issues such as power loss. Prior art hoist brakes were directed at solving some of these issues, but in doing so either ignored other issues or exacerbated the other issues.
While prior art devices have attempted to address the various drawbacks of hoist brake systems, there still exists the need for improved performance of hoist brakes that also provides improved safety while also minimizing maintenance.
An innovative brake system for use with a hoist assembly is disclosed. The brake system incorporates an electro-mechanical device that acts as a fail-safe stopping mechanism for a hoist (or analogous device) that has a default engaged (brake on) position. This allows the brake system to quickly and safely stop a device when power is lost, an emergency signal is provided or any other fault condition (over travel, control failure, drive train failure) and be completely self-contained within the hoist itself.
A spring biases a control arm to maintain the brake system in an engaged position, which applies a clamping force sufficient to prevent any further movement of the hoist (spooling or unspooling). The brake system only allows movement of the hoist under power and when signaled to allow movement. This secondary brake system responds within milliseconds to stop hoist movement within several inches, even at loads of 2,500-4,700 lbs.
During normal operation an embodiment, the electro-mechanical brake is opened is initiate movement through control signals from an independent microprocessor. The microprocessor controls the speed, current draw, and initial release speed of the opening drive system. The opening drive system provides force by taking advantage of an electrical motor which pulls against the torsion spring increasing the rotary torque being applied to the mechanical brake portion of the brake mechanism. Utilization of the microprocessor permits pin point control of the electrical motor, which reduces heat generation from the motor, current demands for the system, and allows increased speed control of the motor while activating the brake system.
The above summary is not intended to describe each illustrated embodiment or every implementation of the subject matter hereof. The figures and the detailed description that follow more particularly exemplify various embodiments.
Subject matter hereof may be more completely understood in consideration of the following detailed description of various embodiments in connection with the accompanying figures, in which:
While various embodiments are amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit the claimed inventions to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the subject matter as defined by the claims.
Attached are drawings of an embodiment of the bucket tray of the present invention as well as detailed drawings of the individual components of the bucket tray. It is understood that the various components disclosed in the drawings may be substituted with equivalent components and are not considered limiting.
The following detailed description should be read with reference to the drawings in which similar elements in different drawings are numbered the same. The accompanying figures depict embodiments of the electro-mechanical brake system of the present invention, and features and components thereof. Any references to front and back, right and left, top and bottom, upper and lower, and horizontal and vertical are intended for convenience of description, not to limit the present invention or its components to any one positional or spatial orientation. The drawings, which are not necessarily to scale, depict illustrative embodiments and are also not intended to limit the scope of the invention. Any reference in the claims to a “hoist” is not intended to limit the scope of the invention to a specific type of hoist, but to any type of rotational lifting or pulling device including winches, cranes, lifts, etc.
An electro-mechanical brake system according to an embodiment of the invention is depicted generally in
As illustrated in
In a disclosed embodiment, the actuation arm 300, caliper 420, and biasing member 610 are mounted to a caliper frame 410. The preferred embodiment comprises a biasing member of one or more torsion springs, but any means of biasing the actuation arm 300 known in the art may be used. The biasing member 610 is preferably housed within a spring box 600 to support and protect the biasing member 610. The biasing member 610 is operably connected to the actuation arm 300, which is also operably connected to an electro-mechanical link 320 that connects the mechanical portion of the electro-mechanical brake system 100 to its electrical portion. Movement of the actuation arm 300 controls activation and movement of the caliper 420.
A brake motor assembly 200 houses the brake motor 250 as well as other components that convert electrical power of the brake motor 250 to mechanical force for the electro-mechanical brake system 100. The brake motor 250 is mounted in a brake motor frame 210. An embodiment of the brake motor frame 210 illustrated in
In a preferred embodiment, the brake motor assembly 200 is connected to the caliper frame 420 by a torsion bar 700. The torsion bar 700 prevents movement of the brake motor assembly 200 with respect to the caliper frame 420, allows for fine tuning and adjustment of the electro-mechanical brake system 100 to account for wear on the various system components. The torsion bar 700 is preferably threaded and adjustable at both ends to provide facilitate adjustments.
In the configuration disclosed in
The link actuation cam 330 is connected to the mechanical portion of the electro-mechanical brake system 100 via electro-mechanical link 320. In the disclosed embodiment, the electro-mechanical link 320 is a roller chain. However, any means of transferring the movement of the link actuation cam 330 to the actuation arm 300 known in the art can be substituted for the electro-mechanical link 320. The electro-mechanical link 320 is coupled to the link actuation cam 330 by connecting and to the actuation arm 300 by connecting links 310, 290. However, any other means of connecting the electro-mechanical link 320 to the actuation arm 300 and link actuation cam 320 known in the art may be used.
Movement of the actuation arm 300 results in operation of the caliper 420. In one embodiment, the actuation arm 300 moves a caliper actuation cam 440, which in turn acts on caliper push pins 450 to move caliper pads 420 together or apart. When caliper pads 420 move together, they act to squeeze against the brake disc 400 to create friction and slow the rotation of a hoist drum 850 (
Movement of the actuation arm 300 from this position allows the caliper pads 420 to release from the brake disc 400 to allow rotation of the drum 850 (“open”). The preferred embodiment utilizes the biasing member 610 to keep the actuation arm 300 in a position where the electro-mechanical brake system 100 is fully engaged (i.e., the caliper pads 420 are fully pressed against the brake disc 400. In this configuration, movement of the brake disc 400 can only occur with power to the brake motor 250 and a control signal. This arrangement allows the electro-mechanical brake system 100 to act as a fail-safe brake mechanism for a hoist system 1000 or other analogous device.
In a preferred embodiment, the maximum movement of the actuation arm 300 is restricted by a clamping position limit switch 500 and an open position limit switch 510. The clamping position limit switch 500 controls the maximum movement of the actuation arm 300 in the unbiased direction and the open position limit switch 510 controls the maximum movement of the actuation arm 300 in the biased direction.
The hoist drum pulley 840 is mechanically coupled to and rotates the hoist drum 850. In the illustrated embodiment, the brake disc 400 is mounted between the hoist drum 850 and the hoist drum pulley 840. This arrangement allows direct application of braking force on both the hoist motor 810 and the hoist drum 850. In the preferred embodiment, the hoist drum, brake disc 400, and drum pulley 840 all share an axis of rotation 1010. The present invention also contemplates the brake disc 400 being mounted on the opposite side of the hoist drum 850 from the hoist drum pulley 840.
Another embodiment of the invention includes a means of providing additional monitoring and control of the hoist drum 850 movement. As shown in
Through an algorithm in the controller 900, the encoder count is used to calculate the position of the cable travel based on the diameter growth created from the cable building up on the hoist drum 850. This system is similar to U.S. Pat. No. 8,328,165, which is incorporated herein by reference in its entirety.
By taking into account the number of cable wraps per layer, the diameter of the cable, and the diameter of each layer and accounting for the ratio difference between each encoder and the speed ratio of the hoist motor 810 and the ratio introduced by the ratio between the drum sprocket 950 and the limit switch sprocket 940, a greatly increased accuracy of monitoring and control is established.
For example, a ratio of 3,600 revolutions of a limit switch encoder per hoist drum 850 rotation can be accomplished. When the controller 900 indicates variations between the actual hoist drum 850 rotation and expected values from the hoist motor 810 rotation outside of acceptable limits, the controller 900 can shut down the hoist motor 810. This feature acts as an additional fail-safe to that provided by the electro-mechanical brake system 100.
Various embodiments of systems, devices, and methods have been described herein. These embodiments are given only by way of example and are not intended to limit the scope of the claimed inventions. It should be appreciated, moreover, that the various features of the embodiments that have been described may be combined in various ways to produce numerous additional embodiments. Moreover, while various materials, dimensions, shapes, configurations and locations, etc. have been described for use with disclosed embodiments, others besides those disclosed may be utilized without exceeding the scope of the claimed inventions.
Persons of ordinary skill in the relevant arts will recognize that the subject matter hereof may comprise fewer features than illustrated in any individual embodiment described above. The embodiments described herein are not meant to be an exhaustive presentation of the ways in which the various features of the subject matter hereof may be combined. Accordingly, the embodiments are not mutually exclusive combinations of features; rather, the various embodiments can comprise a combination of different individual features selected from different individual embodiments, as understood by persons of ordinary skill in the art. Moreover, elements described with respect to one embodiment can be implemented in other embodiments even when not described in such embodiments unless otherwise noted.
Although a dependent claim may refer in the claims to a specific combination with one or more other claims, other embodiments can also include a combination of the dependent claim with the subject matter of each other dependent claim or a combination of one or more features with other dependent or independent claims. Such combinations are proposed herein unless it is stated that a specific combination is not intended.
Any incorporation by reference of documents above is limited such that no subject matter is incorporated that is contrary to the explicit disclosure herein. Any incorporation by reference of documents above is further limited such that no claims included in the documents are incorporated by reference herein. Any incorporation by reference of documents above is yet further limited such that any definitions provided in the documents are not incorporated by reference herein unless expressly included herein.
For purposes of interpreting the claims, it is expressly intended that the provisions of 35 U.S.C. § 112(f) are not to be invoked unless the specific terms “means for” or “step for” are recited in a claim.
