Patent Application
20130240069
The present disclosure generally relates to a hydraulic system and, more particularly, to a tank for receiving and holding hydraulic fluid.
Hydraulic systems are used in a variety of applications to generate mechanical power. These systems typically employ a tank for holding a reservoir of hydraulic fluid or oil. Hydraulic fluid from the tank may be pumped to motors, cylinders, or other hydraulic devices. The volume of hydraulic fluid required by the hydraulic device may change during operation, and therefore hydraulic fluid is also returned to the tank.
Hydraulic fluid returning to the tank must often be reconditioned for reuse in the hydraulic system. First, the returning hydraulic fluid often has an elevated temperature that may be detrimental to the components used in the hydraulic system. Thus, the fluid may be cooled. Additionally, as the hydraulic devices are operated, the hydraulic fluid is placed under alternating high and low pressures that may cause air to become entrained in the fluid. Entrained air in the hydraulic fluid may cause cavitation and excessive noise as it cycles through the system, thereby accelerating component wear. Accordingly, it is often desirable to deaerate the hydraulic fluid in the tank, prior to reuse in the hydraulic system.
Practical constraints on tank size may limit the capacity for cooling and deaerating the hydraulic fluid. In general, larger tank sizes are preferred because they provide more surface area for exchanging heat to cool the fluid, and have additional space that may be used to reduce the fluid flow velocity, thereby to release air entrained in the hydraulic fluid. In many applications, however, only a limited amount of space is available for the tank. This is particularly true for mobile machines, where smaller tanks are used not only to meet the limited amount of available space but also to reduce weight and increase fuel efficiency.
The known tank designs that attempt to deaerate hydraulic fluid are overly large and complex. For example, U.S. Patent Application Publication No. 2003/0233942 to Konishi discloses a fluid tank having a built in cyclone device. The cyclone device is provided as part of a filter assembly that is disposed in a vertical pipe extending through the tank. The construction of the Konishi device, however, is complex to manufacture, requires a significant amount of vertical space, and is difficult to maintain.
In accordance with one aspect of the disclosure, a tank is provided for holding a hydraulic fluid, the tank including a housing defining an interior chamber, the housing including opposed first and second end walls and opposed first and second side walls. A primary baffle is disposed inside the housing and divides the interior chamber into an inlet chamber and an outlet chamber, with a primary gap between the primary baffle and the housing fluidly communicating between the inlet chamber and the outlet chamber, and the primary baffle defines a contact surface facing the inlet chamber. A first fluid inlet is coupled to the first end wall, fluidly communicates with the inlet chamber, and is oriented along a first inlet axis that intersects the contact surface. A fluid outlet is coupled to the second end wall and fluidly communicates with the outlet chamber.
In another aspect of the disclosure that may be combined with any of these aspects, a tank is provided for holding a hydraulic fluid, the tank including a housing defining an interior chamber, the housing having opposed first and second end walls and opposed first and second side walls. A primary baffle is disposed inside the housing and divides the interior chamber into an inlet chamber and an outlet chamber, with a primary gap between the primary baffle and the housing fluidly communicating between the inlet chamber and the outlet chamber, and the primary baffle defines a contact surface facing the inlet chamber. A first weir is coupled to the primary baffle contact surface and extends into the inlet chamber, and a first fluid inlet is coupled to the first end wall, fluidly communicates with the inlet chamber, and is oriented along a first inlet axis that intersects the contact surface. A fluid outlet is coupled to the second end wall and fluidly communicating with the outlet chamber.
In another aspect of the disclosure that may be combined with any of these aspects, a tank is provided for holding a hydraulic fluid, the tank including a housing defining an interior chamber, the housing including opposed first and second end walls and opposed first and second side walls. A primary baffle is disposed in the housing and divides the interior chamber into an inlet chamber and an outlet chamber, a primary gap between the primary baffle and the housing fluidly communicating between the inlet chamber and the outlet chamber, and the primary baffle defines a contact surface facing the inlet chamber. A first weir is coupled to the primary baffle contact surface and extends into the inlet chamber, and a second weir is coupled to the primary baffle contact surface, extends into the inlet chamber, and is spaced from the first weir. A secondary baffle is coupled to the second side wall and extends partially across the inlet chamber, the secondary baffle being oriented substantially vertically and spaced from the first end wall to form a vortex chamber between the first end wall and the secondary baffle. A first fluid inlet is coupled to the first end wall, fluidly communicates with the inlet chamber, and is oriented along a first inlet axis that intersects the contact surface. A fluid outlet is coupled to the second end wall and fluidly communicates with the outlet chamber.
Embodiments of a tank for holding a hydraulic fluid are disclosed herein. The tank may include several features that reduce the velocity of fluid flow through the tank, thereby to deaerate the hydraulic fluid, and improve mixing with cooled hydraulic fluid provided to the tank. Fluid inlets are oriented away from a surface of the fluid of the tank, and instead are directed toward a primary baffle that separates the tank into inlet and outlet chambers. The primary baffle creates a circuitous fluid flow that directs fluid through the tank in a manner that promotes recirculation, mixing, and deaeration. Additionally, one or more weirs may be provided on the primary baffle to further reduce fluid flow velocity. Still further, a secondary baffle may be provided in the inlet chamber that separates a portion of the fluid flow into a vortex chamber, thereby to further deaerate the fluid. Deaerated fluid flows into an outlet chamber that communicates with a hydraulic pump, where the hydraulic fluid may be delivered to the hydraulic system components.
A side view of a machine, in this example a skid steer loader 20, is shown in
The skid steer loader 20 shown in
The hydraulic tank 22 may have multiple fluid inlets and outlets as schematically shown in
A primary baffle 82 is disposed in the hydraulic tank 22 and configured to reduce fluid velocity in the tank. As best shown in
One or more projections may be formed on the primary baffle contact surface 90 to further reduce fluid velocity. As best shown in
The second side wall 66 may be formed with a shoulder 100 that defines a shelf surface 102 in the inlet chamber 84, as best shown in
As best shown in
A secondary baffle 108 may be provided near the shelf surface 102, in the second portion of the inlet chamber 84, to further reduce the velocity of fluid flowing through the tank. As best shown in
The first and second fluid inlets 40, 42 are oriented to generate inlet fluid flows that reduce the amount of aeration generated in the hydraulic tank 22. In conventional tanks, fluid inlet flows may breach the fluid level inside the tank, thereby generating additional aeration of the fluid inside the tank. Referring now to
The present disclosure is applicable to machines having hydraulic systems that employ a fluid tank, such as a hydraulic tank, to hold a reservoir of fluid. The hydraulic tank 22 is configured to reduce the velocity of the fluid, thereby deaerating the fluid. Additionally, the hydraulic tank 22 promotes mixing of the fluid, allowing for more efficient cooling of the fluid. The hydraulic tank 22 generates a circuitous fluid path that deaerates and mixes the fluid in a relatively small sized tank.
More specifically, the hydraulic tank 22 may create one or more loops, passes, spiral flows, or other flow paths that promote fluid mixing and deaeration. As a result, the tank configuration itself produces advantageous flow patterns without requiring separate vortex chambers or other complex structures that require additional space or are difficult to assemble and maintain.
In the exemplary embodiment, the tank 22 has a fluid flow path extending from inlets 40, 42 to the outlet 46. A first portion of the fluid flow path includes an inlet loop path, identified by reference numeral 120 in
A second portion of the fluid flow path includes a split flow path identified by reference numeral 121 in
A third portion of the fluid flow path includes a vortex flow path identified by reference numeral 122 in
A fourth portion of the fluid flow path includes an outlet flow path 124. The outlet flow path 124 is formed by the first and second end walls 60, 62 and the first and second side walls 64, 66. The outlet chamber 86 is formed as a sump portion of the tank 22 that receives fluid flowing through the primary gap 88 (either directly from the inlet chamber 84 via the split flow path 121 or via the vortex flow path 122). The pump 54 draws fluid out of the fluid outlet 46 along the outlet flow path 124.
Accordingly, fluid flowing from the first and second fluid inlets 40, 42 to the fluid outlet 46 may traverse a circuitous path that crosses the interior chamber 58 multiple times. First, in the inlet chamber 84, the fluid may cross the interior chamber 58 twice as the flow follows the inlet loop path 120. A portion of the fluid will then flow through the vortex chamber 110 prior to reaching the outlet chamber 86. In the outlet chamber 86, the fluid crosses the interior chamber 58 an additional time before exiting the fluid outlet 46. The circuitous flow path promotes mixing and deaeration in a tank having a relatively small footprint.
Each of the aspects and features disclosed herein may be combined with any other aspect or features noted in this disclosure. For example, the following features and aspects may be combined: a first weir coupled to the primary baffle contact surface and extending into the inlet chamber; a second weir coupled to the primary baffle contact surface and extending into the inlet chamber, the second weir being spaced from the first weir; the first weir having a first weir height, the second weir having a second weir height, and the first weir height being less than the second weir height; the contact surface of the primary baffle generally extending longitudinally from the first end wall to the second end wall; the primary baffle contact surface having a continuous arcuate shape; the second side wall being formed with a shoulder defining a shelf surface in the inlet chamber; a secondary baffle coupled to the second side wall and extending partially across the inlet chamber, the secondary baffle being oriented substantially vertically and spaced from the first end wall to form a vortex chamber between the first end wall and the secondary baffle; the first fluid inlet being positioned above the primary baffle and the first inlet axis being angled downwardly relative to a horizontal reference line; a second fluid inlet coupled to the first end wall, fluidly communicating with the inlet chamber, and oriented along a second inlet axis that intersects the contact surface, in which the first fluid inlet fluidly communicates with a source of cooler fluid and the second fluid inlet fluidly communicates with a source of warmer fluid; and the primary baffle further comprising at least one recess defining a relief gap configured to permit passage of air. The above-listed aspects and features are merely exemplary, as other aspects and features may be disclosed herein that may further be combined.
It will be appreciated that the foregoing description provides examples of the disclosed assembly and technique. However, it is contemplated that other implementations of the disclosure may differ in detail from the foregoing examples. All references to the disclosure or examples thereof are intended to reference the particular example being discussed at that point and are not intended to imply any limitation as to the scope of the disclosure more generally. All language of distinction and disparagement with respect to certain features is intended to indicate a lack of preference for those features, but not to exclude such from the scope of the disclosure entirely unless otherwise indicated.
Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context.
Accordingly, this disclosure includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the disclosure unless otherwise indicated herein or otherwise clearly contradicted by context.
