Apparatus for Servicing Automatic Transmissions and the Like

1. Field of the Invention

The subject invention relates to vehicle maintenance and, more particularly, to an apparatus for flushing and filling automatic transmissions with transmission fluid.

2. Description of Related Art

Flushing and filling automatic transmissions with fluid or oil according to prior art methods is a relatively time-consuming and cumbersome process. The conventional method is to change the fluid in the pan of the transmission. The pan typically holds from 1 to 5 quarts of the 7 to 15 quarts of oil which are in the transmission. Hence, this conventional service is ineffective, since it mixes new fluid with a large quantity of used fluid. More recently there have been efforts to change all the fluid by disconnecting the fluid hose and draining the fluid into a waste oil sump while manually pouring new fluid into the transmission dipstick hole. This procedure has proved inadequate and unsafe, and has resulted in damage to transmissions on which it has been used.

It is therefore an object of the invention to provide apparatus which simplifies and reduces the time involved in flushing and refilling an automatic transmission.

It is another object of the invention to provide apparatus which automatically flushes used transmission fluid and refills the transmission with new fluid with minimal operator intervention.

According to the invention, apparatus is provided which permits used transmission fluid to be withdrawn from the transmission while new or replacement fluid is being simultaneously pumped in. In one embodiment, the automatic transmission's own fluid pump is employed to pump fluid out of the transmission. The flow rate created by that pump is measured and used to set the rate at which a second pump in the apparatus pumps new or replacement fluid into the transmission. By regulating the flow rates into and out of the transmission to be equal, the fluid may be entirely replaced without risk of damage to the transmission.

The objects and features of the present invention, which are believed to be novel, are set forth with particularity in the appended claims. The present invention, both as to its organization and manner of operation, together with further objects and advantages, may best be understood by reference to the following description, taken in connection with the accompanying drawings, of which:

FIG. 1 is a pictorial perspective view illustrating the preferred embodiment in position for flushing a transmission;

FIG. 2 is an elevational pictorial view illustrating interconnections according to the preferred embodiment;

FIG. 3 is a schematic diagram of the preferred embodiment;

FIG. 4 is an electrical schematic diagram of electrical componentry of the preferred embodiment; and

FIG. 5 is a schematic diagram of an alternate embodiment.

The following description is provided to enable any person skilled in the art to make and use the invention and sets forth the best modes contemplated by the inventor of carrying out his invention. Various modifications, however, will remain readily apparent to those skilled in the art, since the generic principles of the present invention have been defined herein specifically to provide a compact, convenient transmission flusher apparatus adaptable for use with various vehicles and automatic transmissions.

As shown in FIG. 1, the automatic transmission flusher apparatus 11 according to the preferred embodiment includes first and second hoses 13 and 15. These hoses 13, 15 are shown entering the engine compartment of an automobile 17.

As is known in the art, cooler lines 21, 22 (FIG. 2) extend between the automatic transmission and the radiator 16 of the typical automobile. Fluid is circulated to and through the radiator 16 and back to the transmission in order to cool the fluid. The automatic transmission and its internal pump and other componentry may be viewed as a subassembly of the automobile.

According to the preferred embodiment, one of these cooler lines 21 is disconnected from the radiator 16. The disconnected cooler line 21 is then connected to hose 13, thereby establishing a path for used transmission oil to flow from the transmission into the flusher apparatus 11. The second hose 15 of apparatus 11 is connected to the cooler port 19 of the radiator 16 where the line 21 from the transmission now connected to hose 13 was previously connected. Other interconnections of hoses 13, 15 in the fluid flow path between the transmission and radiator are, of course, possible consistent with the overall operation described herein. For example, line 13 could be hooked up, at the transmission pump output at which hose 21 is connected.

In overall operation, the engine of automobile 17 is started. When the engine is started, the pump associated with the transmission of automobile 17 activates and begins to pump transmission fluid into hose 13. The flusher apparatus 11 is then activated and begins to simultaneously pump new transmission fluid into the transmission through hose 15, while simultaneously extracting the old transmission fluid through hose 13. This operation will now be described in detail in connection with the detailed drawings of FIGS. 2 and 3.

As noted above, the first hose 13 is connected to the hose 21 which normally conducts fluid between the transmission of the automobile 17 and the radiator. For this purpose, hose 13 is provided with a suitable hose coupling which mates with the hose coupling of hose 21.

As illustrated in FIG. 3, the fluid flow path through hose 13 to a waste storage tank 33 includes pressure-sensing switch 23, a pressure gauge 25, an electric valve 27, a flow control valve 29, and a sight glass flow meter 31, which provides a visible measurement of flow in gallons per minute. The pressure-sensing switch 23 detects fluid flow in hose 13. When the switch 23 detects fluid flow, it enables operation of the flusher apparatus 11, as hereafter described in more detail in conjunction with FIG. 4.

The pressure gauge 25 shows the fluid flow pressure in pounds per square inch in hose 13. The electric valve 27 either opens or closes the fluid flow path through hose 13 to waste storage tank 33. The flow control valve 29 (3000 psi) is manually adjusted to reduce or increase the fluid flow rate. The sight glass 31 allows visual indication of fluid flow through hose 13 in gallons per minute (0-20 gallons per minute).

The fluid flow path for injecting new oil into the transmission through hose 15 includes a fluid holding or storage tank 35 for new (unused) oil, a 12-volt pump 37, a flow control valve 39, a sight glass flow meter 41, a return pressure gauge 43, and a check valve 45. When activated, the pump 37 causes transmission fluid to be pumped from the tank 35 through hose 15, and ultimately into the transmission of the automobile 17. The sight glass 41 and return pressure gauge 43 allow visual indications of the return pressure and return flow through hose 15 in gallons per minute and pressure in pounds per square inch (psi), respectively.

The flow control valve 39 permits the operator of the flusher apparatus to manually adjust the flow rate through hose 15 so that it may match the flow rate at which used transmission fluid is extracted through hose 13. The check valve 45 (5 psi to 100 psi) prevents fluid from coming back down the line.

In overall operation of the apparatus of FIG. 3, the hoses 13 and 15 are appropriately connected. Then the automobile engine is started, resulting in activation of the pump associated with the automobile's automatic transmission. This pump begins to pump used transmission fluid into hose 13. Fluid cannot flow into waste storage tank 33, however, because of operation of the electric valve 27, which closes the fluid flow path from hose 13. The fluid flow path from hose 13 remains closed while the pressure in hose 13 is building. The flow control valve 37 on the new fluid side is also normally off or closed at this time.

The pressure is then read from pressure gauge 25 to give an indication of whether there may be a problem with operation of the transmission pump. This pressure reading may initially be 40 or 50 psi above the actual pump pressure. Various transmissions have various pump pressures, for example, from 5 to 30 psi.

After the pressure is checked via gauge 25, the operator grips the flow control valve 39. Electric valve 27 and the 12-volt pump 37 are then simultaneously activated. Waste transmission fluid then flows from the transmission to the waste storage tank 33. The flow rate to the waste storage tank 33 is read from sight glass 31 and flow control valve 39 is adjusted to achieve the same flow rate. In this manner, old transmission fluid is pumped from the transmission at the same time and at the same rate as new transmission fluid is being injected into the transmission through hose 15. The flow control valve 29 in the used fluid path provides for additional adjustment, for example, in case the pressure or flow rate at which used fluid is being pumped exceeds that at which the transmission can accept new fluid from hose 15.

Once the waste storage tank 33 is filled, it may be drained by a drain path 51, also shown in FIG. 3. Drain path 51 includes a drain pump 53 and check valve 55, which connect to hose 15. When it is desired to drain the waste fluid in tank 33 hose 15 is disconnected from port 19 and connected to a suitable drain or waste oil storage facility, and the drain pump 53 is activated, pumping waste fluid from tank 33 to such a suitable drain or waste oil storage facility.

Electrical connections of the apparatus according to the preferred embodiment are shown in FIG. 4. According to FIG. 4, a 12-volt battery 61 is connected to supply positive power to a three-way toggle switch 65 activated by a switch button 63. One pole 64 of the switch 65 is connected to a first terminal of the pressure-sensing switch 23. The pressure-sensing switch 23 has a second terminal connected in common to a first terminal of a 12-volt lamp 69 and to a first terminal of the electric valve 27. The second terminal of the electric valve 27 is grounded, as is the second terminal of the 12-volt indicator lamp 69. The 12-volt power connected to the electrical valve 27 is also connected to a first terminal of the 12-volt pump 37, which has a second terminal connected to ground. Thus, when the switch 63 is placed in the AUTO START position after pressure equalization has been obtained, and assuming that the pressure-sensing switch has detected fluid pressure in hose 13, electric power is simultaneously applied to the electric valve 27, causing it to open and to the 12-volt pump 37, causing it to be activated to pump new transmission fluid through hose 15 and, ultimately, into the transmission of automobile 17.

If the switch button 63 is moved to the DRAIN position, 12-volt power is supplied to the second pole 66 of the three-way switch 65 and, accordingly, to the 12-volt pump 53 and the 12-volt indicator lamp 67. In this position, pump 53 empties the contents of waste storage tank 33 into a suitable waste storage or disposal facility.

As illustrated in FIG. 1, the apparatus shown in FIGS. 3 and 4 may be conveniently mounted in a portable, wheeled housing, which may be conveniently moved to and from various positions of use and storage. The 12-volt battery 61 of FIG. 4 is preferably the vehicle battery electrically interconnected to the electrical circuitry of FIG. 4 by jumper cables leading into the wheeled housing. In this manner, the portability of the unit is enhanced, being independent of electrical outlets or other power interconnections, which may be unavailable.

FIG. 5 illustrates an alternate embodiment, which omits the sight glasses 31, 41 of FIG. 3. This embodiment operates like that of FIG. 3 in all respects except that omission of the sight glasses is compensated for by visually monitoring the level of the fluid in the dipstick hole and assuring that valves 29 and 39 are adjusted to a flow rate which maintains the fluid level constant, preferably at the "full" mark typically present. Such a check may be made by simply looking into the hole or by monitoring a "wand" or measuring device which extends out of the hole. Such a visual check is also useful and preferably employed during operation of the embodiment of FIG. 3 to assure precise flow rate adjustment. The embodiment of FIG. 5 further includes a sight glass 54. As fluid is replaced, one observes the fluid color through sight glass 54. When the color changes from brown to red, the old fluid has been completely replaced and the service is done.

Those skilled in the art will appreciate that various adaptations and modifications of the just-described preferred embodiment can be configured without departing from the scope and spirit of the invention. Therefore, it is to be understood that, within the scope of the appended claims, the invention may be practiced other than as specifically described herein.