Patent Application
20050139019
The present invention relates to an air turbine starter, and more particularly, an air turbine starter having a low pressure differential check valve.
An air turbine starter (ATS) is typically used to start an aircraft turbine engine, for example, a gas turbine jet engine. The ATS is typically mounted to the jet engine through a gearbox or other transmission assembly and a cover plate or wall is located between the starter and gearbox housings. The gearbox transfers power from the ATS to the engine to start the engine.
Many air turbine starters typically include lubrication to run properly. Some air turbine starters use an assisted wet cavity design (AWC) to assist in lubrication. These designs include a turbine starter housing having a mounting face or mounting flange that is sealingly engaged with, and coupled to, the gearbox such that a porting system, that allows free transfer of lubricating oil between the gearbox and the starter, is defined. Each port in the porting system is typically in fluid communication with passages within the starter housing so that oil can be distributed within the starter, and are located in portions of the starter-gearbox assembly such that they act as sump passages or oil return passages.
Typically in AWC designs, air flows freely between the starter and the gearbox. The gearbox may be pressurized or nonpressurized. In a non-pressurized gearbox design, the gearbox pressure may be about 0.1-0.3 psi above ambient pressure. At times, the starter housing may become punctured, causing a breach in the starter structure and a change in pressure. In such case, the starter pressure may drop to equalize with ambient pressure. Consequently, in the case of the non-pressurized design, the pressure differential between the gearbox and starter may be about 0.1 to 0.3 psi. Though this pressure differential may be relatively small, excessive oil may still leak from the gearbox to the starter and, consequently, out through the breach. Generally, in such an event, a check or reed valve is used to counteract the oil loss. However, because the pressure differential between the starter and gearbox is small, it has been found that these valve types may not work consistently.
Accordingly, there is a need for an aircraft turbine starter with improved fluid flow control in the condition of starter housing puncture. Additionally, there is a need for an air turbine starter with the ability to operate during starter housing breach, and in particular, in instances when the breach causes a low pressure differential between the starter and gearbox. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.
The present invention provides an air turbine starter including a starter housing and a check valve. The starter housing is adapted to couple to a gearbox assembly, and includes an opening configured to provide fluid communication between the gearbox assembly and the starter housing. The check valve assembly is disposed within the opening and includes a valve body, a valve seat, and a valve element. The valve body has an inlet port, an outlet port, and a flow passage therebetween. The valve seat is coupled to the valve body and extends at least partially into the flow passage. The valve seat also includes an opening therethrough. The valve element is disposed within the flow passage between the valve seat and the valve body outlet port and is configured to translate axially between an open position and a closed position in response to a pressure differential between the inlet and outlet ports.
In another embodiment, and by way of example only, a check valve assembly having a valve body, an valve seat, and a valve element is provided. The valve body has an inlet port, an outlet port, and a flow passage therebetween. The valve seat is coupled to the valve body and extends at least partially into the flow passage. The valve seat includes an opening therethrough. The valve element is disposed within the flow passage between the valve seat and the valve body outlet port and is configured to translate axially between an open position and a closed position in response to a pressure differential between the inlet and outlet ports.
In yet another embodiment, a check valve assembly comprising a backing plate, a cage, a valve seat and a valve element is provided. The backing plate includes an outlet port. The cage is coupled to the backing plate and has an inlet port. A flow passage extends between the inlet port and the outlet port. The valve seat is coupled to the backing plate, and extends at least partially into the flow passage and further includes an opening therethrough. The valve element is disposed within the flow passage between the valve seat and the inlet port, and is configured to translate axially between an open position and a closed position in response to a pressure differential between the inlet and outlet ports.
Other independent features and advantages of the preferred air turbine starter will become apparent from the following detailed description, taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention.
Before proceeding with the detailed description, it should be appreciated that the present invention is not limited to use in conjunction with a specific type of rotating machine. Thus, although the present invention is, for convenience of explanation, depicted and described as being implemented in a turbine starter, it should be appreciated that it can be implemented in numerous other machines including, but not limited to, a gas turbine engine, a hydraulic pump, a water pump, or various other chemical and industrial pumps.
Turning now to the description, a cross sectional view of an exemplary air turbine starter (ATS) that is used to initiate the rotation of a larger turbine, such as a turbofan jet engine, is depicted in
A turbine wheel 122 is rotationally mounted within the housing assembly turbine section 104. In particular, the turbine wheel 122 has an output shaft 124 that extends from a hub 126, through the exhaust housing 120, and into the housing assembly output section 106. The turbine wheel output shaft 124 is rotationally mounted in the housing assembly output section 106 by bearing assemblies 128. A gear 132 is coupled to the turbine wheel output shaft 124, and meshes with a compound planetary gear train 134. The compound planetary gear train 134 engages a ring gear 138 and a hub gear 142, which is in turn coupled to an overrunning clutch 144. During operation of the ATS 100, this gearing configuration converts the high speed, low torque output of the turbine wheel output shaft 124 into low speed, high torque input for the overrunning clutch 144.
The overrunning clutch 144, as noted above, is coupled to the hub gear 142, which is supported by another bearing assembly 146. A drive shaft 148 extends from the overrunning clutch 144, through the turbine housing output section 106, and is coupled to a turbine output shaft 152. The output shaft 152 is, in turn, coupled to the turbofan jet engine gearbox 171.
The gearbox 171 typically includes a plurality of passages (not shown) through which oil freely passes to supply lubrication to the gearbox 171 components. The passages are in fluid communication with oil flow passages within the turbine housing assembly output section 106 via openings 174 (shown in
Turning back to
Turning to
The check valve assembly 173 includes a valve body 181, a valve element 177, and a valve seat 179. The valve element 177 is preferably held between the valve seat 179 and valve body 181 to allow the valve element 177 to translate axially between an open and closed position in response to a pressure differential that may be present between the ATS 100 and the gearbox 171. Each of the valve assembly 173 components will now be discussed.
The valve seat 179 and valve body 181 are generally ring-shaped and each include through channels 180a, 180b that each comprise part of a flow passage 182 allowing fluid communication between the ATS 100 and gearbox 171 oil passages. The valve body 181 is preferably a two-piece assembly that includes a backing plate 175 and a cage 195 coupled together and configured to hold the valve seat 179 in place. To this end, located along the inner periphery of the backing plate 175 is a coupling portion 183 used to couple the valve seat 179 to the plate 175. In this embodiment, the coupling portion 183 is an annular flange formed on the plate 175, however, as will be appreciated, the coupling portion 183 may also be configured in any other manner so as to couple the valve seat 179 and plate 175 together. The valve seat inner periphery 184 fits under the annular flange 183 and aids in anchoring the valve seat 179 to the plate 175. The valve seat is preferably elastomeric, but, it will be appreciated that the valve seat may be one of numerous other configurations, such as smoothly ground. The valve seat 179 further includes two concentric annular protrusions 189, 191 formed thereon and that protrude therefrom. The protrusions 189, 191 are spaced apart so as to be able to accept and sealingly couple to the cage 195. A groove 193 formed on the underside of the cage 195 sealingly couples with the outer annular protrusion 191. As a result, the cage 195, valve seat 179 and plate 175 are coupled such that the innermost annular protrusion of the valve seat 189 is captured between the annular flange 183 and cage inner peripheral surface 186. Accordingly, the innermost annular protrusion 189 extends partially into the flow passage 182, the importance of which will be discussed further below.
The cage 195 preferably includes a trap 196 located on the opposite side of cage 195 from the groove 193. The trap 196 preferably has a tri-spoke configuration that extends across the flow passage 182. It will be appreciated that this is merely exemplary and that instead of a spoke configuration, the trap 196 can be, for instance, a lattice-structure, cross-structure or any other configuration able to position the valve element 177 between cage 195 and the valve seat 179. When the cage 195 is coupled to the valve seat 179, a clearance 187 is provided between the cage 195, more specifically, the trap 196, and the innermost annular protrusion 189, within which valve element 177 is disposed. The trap 196 prevents misalignment of the valve element 177 within the flow passage 182, while still allowing fluids or gases to pass through the flow passage 182. It will be appreciated that the trap 196 can also be formed from a separate piece of material than the cage 195, and for example, can be coupled or fixed to or mounted on the cage 195. Preferably, the trap 196 further includes a stop protrusion 198 that extends from the center of the trap 196. into the flow passage 182 to prevent capillary attraction of the valve element 179 to the cage portion 195 and to also limit the distance of axial translation of the valve element 179. The stop protrusion 198 can be formed on or fixed to the trap 196. The protrusion 198 is preferably adjustable so that the clearance 187 between the cage 195 and valve element 177 can be adjusted. Alternatively, the stop protrusion 198 may be formed on the valve element concave surface 197.
Referring back to
Turning to
However, in the event of ATS 100 puncture, the check valve assembly 173 seals the flow passage 182, preferably completely, such that oil and/or air preferably does not pass between the ATS 100 and gearbox 171, as illustrated in
Thus, an aircraft turbine starter having improved fluid flow control in the condition of a starter housing puncture has been provided. Additionally, the air turbine starter provided includes the ability to operate during starter housing breach, and in particular, in instances when the breach causes a low pressure differential between the starter and gearbox.
While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt to a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.
