WO2001061216A2

WO2001061216A2 - Transmission with sensor for engine speed

Info

Publication number: WO2001061216A2
Application number: PCT/US2001/005095
Authority: WO
Inventors: Douglas F. Edwards; Matthew J. Plas; Marty Pierce; Paul Crawford
Original assignee: Mtd Products Inc
Priority date: 2000-02-14
Filing date: 2001-02-14
Publication date: 2001-08-23
Also published as: WO2001061216A3; AU2001241528A1

Abstract

A transmission is provided that can be selectively installed in a lawn care vehicle for use with a plurality vehicle engines. The transmission includes a sensor and a control device for reading the rotational motion of a transmission gear and calculating the RPM s of the vehicle engine based upon the sensor data. The transmission also includes a bi-directional overrunning clutch that is received within a power input gear and an electric clutch brake assembly that is aligned with a bearing member that is partially received by the transmission housing. The transmission includes a stackable pump for use in powering auxiliary equipment. Additional hydraulic pumps can be stacked onto existing units to increase the hydraulic output capacity of the transmission.

Description

IMPROVED TRANSMISSION

Technical Field

This invention relates to the art of transmissions, and more particularly to transmissions that can be used interchangeably with a plurality of engines, especially as related for use on lawn care vehicles. Background Art

Manufacturers of lawn care vehicles are continually searching for new ways to reduce manufacturing costs. One such cost reduction method includes reducing the inventory of the components that are assembled into the final product, which can be accomplished by utilizing similar components adapted for use with different assembly units. One example of this type of adaptation is a transmission that can be used with a plurality of different engine sizes.

One feature of lawn care vehicles measures the revolutions per minute of the vehicle engine. Typically, this accomplished by directly measuring the rotation of an output shaft of the engine. As the engine size of the vehicle is changed for different models of lawn care vehicles, different RPM gauges or measurement devices would be required for each engine units. Therefore, it would be advantageous to provide a single transmission that could be adapted to measure the RPMs of each engine type with which it is used. Another feature of lawn care vehicles implements is the use of hydraulic pumps to power auxiliary equipment, such as a plow for example. Normally, in order to increase hydraulic output power, it is generally known to replace the existing pumping unit with a second larger capacity pump. This requires the manufacturers to stock multiple sizes of hydraulic pumps having different pumping capacities. It would be advantageous to provide a transmission that utilizes stackable hydraulic pumps.

Yet another aspect of lawn care vehicles includes the use of a bi-directional overrunning clutch. While the use of overrunning clutches is well known in the art, typically these types of clutches are communicated to the torque input gear of the axle via a shaft and meshing gear arrangement where it measures the slip of one or more wheels. It would be advantageous to provide a bi-directional overrunning clutch that could be directly coupled and received by the torque input gear to reduce the size requirement of such a clutch assembly. This invention provides new and useful improvements in a lawn care vehicle transmission. Such improvements reduce the cost of assembling lawn care vehicles by reducing the number of different components used in the assembly process

T)isf lnsnrp of the Tnvpntinn It is the object of the present invention to provide a transmission that can be used with a plurality of engines.

It is another object of the present invention to provide a transmission that measures the revolutions per minute of an associated engine.

It is yet another object of the present invention to provide a transmission configured to incorporate multiple stackable hydraulic pumps.

It is still another object of the present invention to provide a transmission with a bi-directional overrunning clutch incorporated into a torque input gear of the axle. It is still yet another to provide a transmission with an electric clutch and brake assembly supported by a bearing, wherein the bearing is received by the transmission housing. Other objects and advantages of the invention will appear from the following detailed description of the preferred embodiment of the invention with reference being made to the accompanying drawings. Brief Description of the Drawings

The invention may take physical form in certain parts and arrangement of parts, a preferred embodiment of which will be described in detail in this specification and illustrated in the accompanying drawings which form a part hereof and wherein: FIGURE 1 is a side view of a lawn care vehicle. FIGURE 2 is a side view of a transmission. FIGURE 3 is a rear view of a transmission. FIGURE 4 is a partial cross sectional view of the transmission.

FIGURE 4a is a partial cross sectional view of a proximity sensor and a control device.

FIGURE 5 is a cross sectional view of a transmission including an over running clutch. FIGURE 5a is a cross sectional view of a bi-directional over running clutch.

FIGURE 6 is a side view of a transmission including an electric clutch brake assembly.

FIGURE 7 is a partial cross sectional view of the hydraulic pump attached to the transmission.

FIGURE 7a is a partial cross sectional view of stacked hydraulic pumps attached to the transmission.

Description of the Preferred Emhodiment

Referring now to the drawings wherein the showings are for purposes of illustrating a preferred embodiment of the invention only and not for purposes of limiting the same, FIGURE 1 depicts a riding mower shown generally at 1. The riding mower 1 includes a frame 2 and four ground engaging wheels 4, 4', 4" and 4'" rotatably attached to the riding mower 1 in a manner well known in the art. An engine 6 is received with in a body 7 of the riding mower, wherein the engine 6 is disposed substantially at the front end 8 of the riding mower 1. A transmission 10, shown best in FIGURES 2 and 3, is fixedly attached to the frame 2 and is communicated to the engine 6 in a manner so as communicate power from the engine 6 to the ground engaging wheels 4, 4' for use in providing mobility to the riding mower 1. In that the operative connection of transmissions and engines are well known in the art, no further explanation will be offered at this point. In the preferred embodiment, transmission 10 includes wheel hubs 13, 14. The wheel hubs 13, 14 are adapted to receive ground engaging wheels 4, 4'. In this manner, the transmission 10 function as part of the frame 2 of the riding mower 1. It is especially noted that, that while the preferred embodiment of the present application is a riding mower 1 , the invention contained herein is applicable to any combination of vehicle having an engine and a transmission operatively attached thereto. Further, this invention is applicable vehicles utilizing implements for lawn care, snow removal or any other use chosen in accordance with sound engineering judgment.

With reference now to FIGURE 2 and 3, the transmission 10 includes a transmission housing 16. In the preferred embodiment, the housing 16 is cast from iron by a process well known in the art. However, any material be used and any method of manufacturing the transmission housing 16 may be chosen with sound engineering judgment. The transmission 10 has a first end 18 and a second end 19. The first end 18 of the transmission 10 includes an input shaft 20. The input shaft 20 is splined at a first end 21 for use in receiving power from the engine 6. In the preferred embodiment, the splined first end 21 of the input shaft 20 is meshingly engaged with a hydraulic motor, not shown. The hydraulic motor receives power from a hydraulic pump, also not shown. The hydraulic pump is operatively connected to the engine 6 in such a manner that as long as the engine is operating, power is continually transferred from the engine to the hydraulic pump, which is further transferred through the hydraulic motor and to the input shaft 20 of the transmission 10. In other words, as long as the engine 6 is running, power is continually being transferred to the transmission 10. The input shaft 20 is rotatably connected to housing 16 via bearings, not shown. In that operatively connecting input shafts to transmission housings is well known in the art, no further explanation will be offered at his point. In this way, rotational power is communicated from the hydraulic motor to the input shaft 20 for use in providing mobility to the riding mower 1 and for use in providing power to drive auxiliary components, not shown, which will be discussed further in a subsequent paragraph.

With continued reference to FIGURE 2 and 3 and now to FIGURE 4, the input shaft 20 is shown received into the housing 16 of the transmission 10. A first gear 30 is shown operatively connected to the shaft 20 in a manner well known in the art. A second gear 33 meshingly engages the first gear 30 at region 35 and is attached to the transmission 10 via bearing 36. Third gear 37 is similarly communicated to second gear 33. The third gear 37 is disposed in proximity to an inner surface 38 of the transmission housing 16. The transmission housing 16 has fashioned therein an aperture 39, which is aligned radially with the third gear 37. In the preferred embodiment, a non-contact proximity sensor 40 is inserted into the aperture 39. However, any sensor means may be used with sound engineering judgment. The sensor 40 is generally elongate having first and second ends 41, 42. The first end 41 of the sensor 40 extends into the housing 16 at sufficient depth so as to operatively detect the rotational motion of the third gear 37. In other words, the sensor 40 does not contact the third gear 37 but is disposed close enough to the gear to identify when a gear tooth is directly over the first end 41 of the sensor and when it is offset therefrom. In the preferred embodiment, an inductive proximity sensor 40 is utilized. However, any means of non-contact sensing may be used with sound engineering judgment as is appropriate for use in transmissions. In that proximity sensors detect proximity of an object without physically contacting the object is well known in the art, no further explanation will be offered at this point. The sensor 40 has an electrical output 44, which is communicated to a control device 50, as shown in FIGURE 4a. In the preferred embodiment, the sensor 40 is fixedly attached to the housing by an adhesive, not shown. However, any such means of attaching the sensor 40 to the housing 16 so that it does not move or come loose during normal operation of the transmission 10 may be chosen with sound engineering judgment. With reference to FIGURES 4 and 4a, the output 44 of the sensor 40 is communicated to a control device 50. In the preferred embodiment, the control device 50 is an electronic device that provides an excitation signal to the sensor 40 and reads an output signal 45 from the sensor 40. The output signal 45 may change from a low to high and high to low state as the gear teeth pass into and out of proximity with the first end 41 of the sensor 40 respectively. The control device 50 converts the rate of the changes, from state to state, of the output signal 44 into rotational speed of the third gear 37. In that, the rotational speed of third gear 37 is directly and constantly proportional to the revolutions per minute, RPMs, of the engine 6, the changes in the output 44 of the sensor 40 is also directly proportional to the RPMs of the engine 6. In this manner, the control device 50 measures the speed of the third gear 37 and translates the speed of the third gear 37 into revolutions per minute, RPMs, of the engine 6. In that the engine 6 may vary in size or model with respect to a transmission 10, the control device 50 may be programmable to adjust for differences in the varying engines so as to calibrate the output 44 of the sensor 40 to the RPMs of the engine 6. In that, data acquisition from sensors are well known in the art no further explanation will be offered at this point. Consequently, any means of receiving sensor and translating the output into revolutions per minute may be chosen with sound engineering judgment. In a manner well known in the art, the control device 50 may output the measurement of the RPMs of the engine 6 to an associated device capable of displaying such information to an operator.

With reference to FIGURE 5a, a bi-directional overrunning clutch is shown generally at 60. The bi-directional overrunning clutch 60 includes a generally cylindrical housing member 62. However, any configuration of housing member 62 may be chosen with sound engineering judgment. Received within the housing member 62 is a bearing 63 that is communicated with an axle member 65 of one of the drive wheels axles. In this manner, the axle member 65 is rotatable with respect to the housing member 62. The housing member 62 has an outer surface 66 that is press fit into a power input gear 70. The power input gear 70 receives power from the input shaft 20 in a manner well known in the art. In this way, the housing member 62 is fixedly attached to the power input gear 70. A hub member 72 has a first aperture 73 that is splined to receive an axle drive member, shown in FIGURE 5. In one embodiment, as depicted clearly in FIGURE 5a, the hub member 72 is a separate component fixedly attached to the power input gear 70 via pin 75. In this manner, power is transferred from the power input gear 72 to the hub member 72 and to the axle drive member 66 for use in providing power to drive the ground engaging wheels 4. In an alternate, discussed further in sequent paragraphs and shown in FIGURE 5, the hub member 72 is integral with the power input gear 70. As the vehicle is moving, power from the input shaft 20 is being transferred to the power input gear 70, to the axle drive member 66 and to the drive wheel 4 of the riding mower or vehicle 1. The axle member 65 is connected to an opposing drive wheel 4' but is not supplied with power by the transmission 10. In other words drive wheel 4' it is free rotate independent of the drive wheel 4. In the event, that the drive wheel 4 rotates at a substantially different rate than the drive wheel 4', for example due to slippage, the difference in the rates of angular speeds between the axle member 65 and axle drive member is detected by the bi-directional overrunning clutch 60. In a manner well known in the art, the bi- directional overrunning clutch 60 engages to rigidly lock the axle member 65 into synchronous rotation with the axle drive member 72. In this manner, the drive wheel 4' is driven synchronously with the drive wheel 4.

With reference now to FIGURE 5, a bi-directional overrunning clutch 80 is shown integrated into the interior of the transmission 10. In an alternate embodiment, as shown in FIGURE 5, the hub member 72 is not separated from but is integral with the power input gear 70 as shown by the power input gear 84. The power input gear 84 is operatively communicated to the input shaft 20 in a manner well known in the art. Thus, the invention as described herein uniquely and compactly inserts a bi-directional overrunning clutch into a power input gear conserving transmission space.

With reference now to FIGURE 6, an electric clutch brake assembly 90 is shown operatively received onto a power supplying shaft 92. The electric clutch brake assembly 90 includes an outer housing 97 generally cylindrical in shape. The outer housing 97 has fashioned therein an aperture 98, which is constructed to receive a bearing 99. The bearing 99 is press fit into the aperture 98 at depth less than the axial length of the bearing 99. The remainder of the bearing 99 is fit into an inner housing member 100. The inner housing member 100 is a rigid extension of the housing 16 and provides support for the bearing 99 and the other internal components of the transmission 10. In this manner, the bearing 100 supports the electric clutch brake assembly 90 at one end and prevents the electric clutch brake assembly 90 from rotating during normal operation. It is especially noted that any configuration of electric clutch brake assembly housing can be used, such as can have an aperture fashioned therein for use in receiving a bearing member. This invention eliminates the requirements of additional bracketing or complex casting of the electric clutch brake assembly housing, which have been previously used to prevent rotation of the electric clutch brake assembly in the prior art by fastening the aforementioned to the transmission housing. Therefore, fewer and less complex components can be used in the transmission. In that electric clutch brakes are well known in the art no further explanation will be offered at this point.

With reference now to FIGURE 3 and 7, the first end 119 of an input shaft 120 is shown extending from a hydraulic pump 123 at a first side 124. The input shaft 120 is received within the hydraulic pump 123 and terminates at a second end 128, which is juxtaposed to the second side 127 within the hydraulic pump 123. In that input shafts and hydraulic pumps are well known in the art, no further explanation will be offered at this point as to the inner workings thereof. A cover plate 126 can be selectively removed from the second side 127 of the pump 123 to expose the second end 128 of the input shaft 120. In the preferred embodiment, the first end 119 of the input shaft 120 is splined to mate with a power transfer gear 130 of the transmission 10. However, any means of connecting the splined shaft 120 to the transmission 10 for use in transferring power to the hydraulic pump 123 may be chosen with sound engineering judgment. A cover, not shown, is included with the transmission 10 and may be selectively removed from the transmission 10 to expose power transfer gear 130 for operative connection with the hydraulic pump 123. In this manner, installation of a hydraulic pump 123 for use in driving auxiliary equipment can be installed and removed as desired. The hydraulic pump 123 is fastened to the transmission housing 16 threaded bolts in a manner well known in the art.

With continued reference to FIGURE 3, 7 and 7a, a second hydraulic pump 134 may be selectively attached to the second side 127 of the first hydraulic pump 123 by removing the cover plate 126 and coupling the first end 138 of the second input shaft 137 of the second hydraulic pump 134 to the second end 128 of the first input shaft 120. The coupling member 140 has a splined aperture, not shown, that meshes with each of the respective input shafts 120, 137. The coupling member 140 transfers power from the first input shaft 120 to the second input shaft 137 for use in providing power to drive the second hydraulic pump 134. In this manner, hydraulic pumps 123, 134 can be stacked to selectively provide additional hydraulic output as desired and sustained by the power output capacity of the transmission. It is especially noted the additional hydraulic pumps, not shown, may be stacked onto the existing pumps by removing the respective cover plates and coupling the respective input shafts similar to that of the aforementioned discussion. Any number of pumps may be stacked according to sound engineering judgment.

While specific embodiments of the invention have been described and illustrated, it is to be understood that these embodiments are provided by way of example only and that the invention is not to be construed as being limited thereto but only by proper scope of the following claims.

Having thus described the present invention, It is now claimed:

Claims

CLAIMS 1. A transmission, comprising: a housing; a shaft for use in receiving power from an associated engine, said shaft rotatably connected with respect to said housing; at least a first gear in operable communication with said shaft; sensing means in operable communication with said at least a first gear, said sensing means for use in sensing rotational motion of said at least a first gear, wherein said sensing means includes at least a first output.

2. The transmission of Claim 1, further comprising: converting means for converting said at least a first output of said sensing means into revolutions per minute of said associated engine.

3. The transmission of Claim 2, wherein said at least a first gear is constantly and directly proportional to the revolutions per minute of said associated engine.

4. The transmission of Claim 3, wherein said sensing means is a proximity sensor.

5. A transmission, comprising: a housing; a shaft for use in receiving power from an associated engine, said shaft rotatably connected with respect to said housing; at least a first gear in operable communication with said shaft, said at least a first gear including an aperture fashioned substantially within the center of said at least a first gear; and, an overrunning clutch assembly having an outer surface, said outer surface of said overrunning clutch fixedly received by said aperture of said at least a first gear.

6. The transmission of Claim 5, wherein said overrunning clutch is a bidirectional overrunning clutch assembly.

7. A transmission, comprising: a housing; a shaft for use in receiving power from an associated engine, said shaft rotatably connected with respect to said housing; at least a first gear received within said housing, said at least a first gear operatively communicated to said shaft; at least a first hydraulic pump operatively engaged with said at least a first gear.

8. The transmission of Claim 7, further comprising: at least a second hydraulic pump operatively connected to said at least a first hydraulic pump.

9. A transmission, comprising: a transmission housing; a shaft for use in receiving power from an associated engine, said shaft rotatably connected with respect to said housing; a clutch assembly operatively communicated to said shaft, said clutch assembly having at least a first clutch support member; and, a bearing having first and second portions, wherein said first portion is operatively received within said transmission housing and wherein said second portion is operatively received within said at least a first clutch housing member.

10. The transmission of Claim 9, wherein said transmission housing includes at least a first support rib fashioned on an interior surface of said transmission housing, and, wherein said first portion of said bearing is received within said at least a first support rib.

11. The transmission of Claim 10, wherein said clutch assembly is an electric clutch and brake assembly.

12. A method for measuring the revolutions per minute of at least a first engine, the steps comprising: providing a transmission operatively attached to said engine, said transmission including: a housing, a shaft for use in receiving power from said at least a first engine, said shaft rotatably connected with respect to said housing, at least a first gear in operable communication with said shaft, sensing means in operable commumcation with said at least a first gear, said sensing means for use in sensing rotational motion of said at least a first gear, and converting means for use in converting said sensor output into revolutions per minute; operating said engine; sensing said rotational motion of said at least a first gear; and, converting said sensor output into revolutions per minute of said engine.