Patent Application
20100200328
The specification generally relates to the field of hydraulic booms for vehicles, such as aerial ladders for instance, and more particularly discloses an articulation mechanism therefore.
Hydraulic booms are used in a wide variety of applications and typically include a work platform, sometimes called a “bucket”, at a free end thereof, in which a worker can be raised and moved by movement of the boom, typically driven with hydraulic components. Hydraulic booms are typically articulated at the other end thereof which connects the vehicle, opposite the work platform, for pivoting about at least two axes. An example of a hydraulic boom is an aerial ladder, in which the boom is typically an extendible ladder leading to the work platform and in which the work platform can typically be swung laterally about a vertical axis intersecting the other end of the boom, and swung upwardly/downwardly about a horizontal axis.
Because hydraulic booms typically include at least one hydraulic actuating cylinder or motor, such as to raise/lower the boom, swing the boom laterally, extend the ladder, and maintain the level of the work platform as the boom is raised and lowered, they have used hydraulic power from a hydraulic power unit, which typically includes at least a hydraulic pump and a hydraulic fluid tank. It was known to provide the hydraulic pump and hydraulic fluid tank in a fixed location relative to the vehicle, and to use hydraulic hoses to interconnect the hydraulic pump and the hydraulic components. However, designing the hydraulic hose configuration in consideration with the freedom of movement of the boom was challenging, at least partially because of the limited flexibility of hydraulic hoses and their limited ability to endure successive flexing over time. Furthermore, the components required to allow pivoting of the boom about two independent axes typically resulted in relatively high thickness, which was less than ideal for the aerodynamics of the vehicle. Henceforth, although known hydraulic boom systems were satisfactory to a certain degree, there remained room for improvement.
The aforementioned limitation relating to wear-resistance of hydraulic hoses can be at least partially overcome in a system such as described herein where the hydraulic power unit is provided in a rotary component of the system, i.e. where it moves with the boom as the boom is swung laterally. If the hydraulic power unit is powered by an electric motor, an electrical cable, which typically has more flexibility and wear-resistance than a hydraulic hose, can be connected to the vehicle and thus be subject to the swinging movement of the boom instead of a hydraulic hose. A further improvement resides in the disclosed coiled configuration of the electrical cable in a fixed component of the system which contributes to minimize the stress to which the electrical cable is subjected to when the boom is swung laterally.
The afore mentioned limitation relating to overall height of the pivoting mechanism can be at least partially overcome with the system described herein by using a hydraulic cylinder to pivot the boom upwardly/downwardly about a horizontal axis which has a base connected to a lower pivot which is provided as part of a rotary component of the system, and which penetrates inside an spacing provided in rotating system of the rotary component.
In accordance with one aspect, there is provided a hydraulic boom system for use on a vehicle, the hydraulic boom system comprising: a boom having a first end receiving a work platform, and a second end, opposite the first end; a fixed component fixedly mountable to the vehicle; a rotary component, rotatably mounted on the fixed component about a vertical axis; a pivotal component, pivotally mounted to the rotary component about a horizontal axis, and receiving the second end of the boom; a hydraulic power unit having an electric motor driven hydraulic pump connected to a hydraulic fluid tank, the hydraulic power unit being made integral to at least one of the rotary component and the pivotal component, and thereby rotating when the rotary component rotates; and an electrical cable connected to the electric motor, and connectable to an electrical power supply located at a fixed position relative to the vehicle.
In accordance with another aspect, there is provided a hydraulic boom system for use on a vehicle, the hydraulic boom system comprising: a boom having a first end receiving a work platform, and a second end, opposite the first end; a fixed component fixedly mountable to the vehicle; a rotary component, rotatably mounted on the fixed component about a vertical axis; a spacing penetrating downwardly at least partially through the fixed component, around the vertical axis; a pivotal component, pivotally mounted to the rotary component about a horizontal axis, and receiving the second end of the boom; a raising hydraulic cylinder between the pivotal component and the rotary component to raise and lower the boom by pivoting the boom about the horizontal axis, the raising hydraulic cylinder having a first end connected to an upper pivot made integral to the pivotal component, between the horizontal pivot axis and the work platform, and a second end connected to a lower pivot which is made part integral to the rotary component, the second end extending downwardly inside the spacing.
In accordance with another aspect, there is provided a hydraulic boom system for use on a vehicle, the hydraulic boom system comprising: a boom having a first end receiving a work platform, and a second end, opposite the first end; a fixed component fixedly mountable to the vehicle; a rotary component, rotatably mounted on the fixed component about a vertical axis; a pivotal component, pivotally mounted to the rotary component about a horizontal axis, and receiving the second end of the boom; a hydraulic power unit having a hydraulic fluid tank and an electric motor driven hydraulic pump connected to the hydraulic fluid tank; and an electrical cable having a coiled portion housed in the fixed component and coiled around the vertical axis, extending upwardly from the coiled portion and connecting the electrical motor at a first end thereof, and having a second end opposite the coiled portion connectable to an electrical power supply located at a fixed position relative to the vehicle.
For the sake of clarity and simplicity, the expression “fixed” as used herein will be used to describe a fixed location or position relative to the vehicle, in contradistinction with the boom which moves relative to the vehicle. Also, the expressions horizontal and vertical are used for simplicity as relative to when the vehicle is resting on a horizontal surface.
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The boom pivoting mechanism 20 includes a hydraulic power unit 34 which, in the illustrated embodiment, is provided as part of the rotary component 28, as will be detailed further below. The hydraulic power unit 34 has a hydraulic pump 36 which is powered by an electric motor 38. The electric motor 38 is connected to an electric cable 40, which leads to the electrical power supply 26 which is in a fixed position relative to the vehicle 42 (see
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A central spacing 62 is provided around the vertical axis 24 in the center of the annular shape of the worm gear 58, and the lower pivot 54 of the raising cylinder 44 (
In this embodiment, the rotary component 28 also has a hydraulic fluid tank 64, which has a hydraulic pump port 66 configured to receive a hydraulic fluid inlet 68 of the hydraulic pump 36. The hydraulic pump 36 is shown in further detail in
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It will appear to person skilled in the art that many variants and alternate embodiments are possible upon considering the teachings of this specification, and that the illustrated embodiment is provided for indicative purposes only. The scope is indicated by the appended claims.
