Structure for changing old engine oil in transmission case by automatic circulation mechanism

A structure for changing engine oil in the transmission case of the engine of a motor vehicle comprises a low pressure oil cylinder and a high pressure automatic throttle valve. The change of engine oil is attained by an oil-changing loop of the automatic circulation system.

FIELD OF THE INVENTION
 The present invention relates generally to a structure for replenishing a
 transmission case with fresh engine oil, and more particularly to a
 structure for draining old engine oil in the transmission case by an
 automatic circulation mechanism.
 DESCRIPTION OF THE PRIOR ART
 The conventional way for changing the engine oil in a transmission case is
 to open up the inlet and the outlet of the transmission case so as to
 enable the old engine oil in the transmission case to be drained via the
 outlet by atmospheric pressure. Such a conventional way for changing the
 engine oil as described above is defective in design, in that the old
 engine oil can not be completely drained out of the transmission case, and
 that the old engine oil residue is attached to the inner wall of the
 transmission case. In order to overcome such deficiencies as described
 above, an improved structure was introduced to the market place. The
 improved structure includes a pump by means of which a suction effect is
 brought about to drain the old engine oil in the transmission case. The
 new engine oil is then injected into the transmission case by
 re-circulating the old engine oil through a re-circulation system which is
 provided with a number of one-way valves and is therefore vulnerable to
 damage, thereby resulting in the crack in the pipe line of the
 re-circulation system. As a result, the transmission case may be also
 damaged. In other words, the oil-changing loop of the re-circulation
 system is too complicated to work effectively and precisely.
 SUMMARY OF THE INVENTION
 The primary objective of the present invention is therefore to provide an
 improved structure for changing engine oil in the transmission case, which
 is free from the deficiencies of the conventional oil-changing structure
 described above.
 In keeping with the principle of the present invention, the foregoing
 objective of the present invention is attained by an engine oil changing
 structure which consists essentially of a low pressure oil cylinder and a
 high pressure automatic throttle valve. The low pressure oil cylinder is
 provided with a piston which divides the low pressure oil cylinder into an
 upper portion (new oil area) and a lower portion (old oil area).The oil
 cylinder is provided at the top thereof with a new oil inlet and an air
 pipe which is connected serially with an air switch, an air adjusting
 valve and an air pressure gauge. The new oil area is provided with a new
 oil pipe connected therewith, whereas the old oil area is provided with an
 old oil pipe connected therewith. The new oil pipe and the old oil pipe
 are controlled by an oil passage switch, which is connected with a first
 oil pipe which is in turn connected with an oil distributing valve. The
 oil distributing valve is connected with the high pressure automatic
 throttle valve and a second oil pipe which is connected serially with a
 first oil meter and an oil filter bud. A third oil pipe is connected with
 an oil pressure gauge. A fourth oil pipe is connected serially with the
 high pressure throttle valve and a three-way valve which is connected at
 one end thereof with an oil replenishing tank, and at other end thereof
 with a second oil meter. The new oil pipe is connected with another
 three-way valve.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
 As shown FIGS. 1-3, an engine oil changing structure of the present
 invention comprises a low pressure oil cylinder 1 and a high pressure
 automatic throttle valve 2.
 The low pressure oil cylinder 1 is provided with a piston 11 which divides
 the low pressure oil cylinder 1 into an upper portion 12 (new oil area)
 and a lower portion 13 (old oil area). The piston 11 has a V-shaped end,
 as shown by A--A in FIG. 6 and by B--B in FIG. 7. As a result, the contact
 area of the piston 11 with the inner wall of the low pressure oil cylinder
 1 is reduced. Accordingly, the mechanical friction between the piston 11
 and the low pressure oil cylinder 1 is minimized. The oil cylinder 1 is
 provided at the top thereof with a new oil inlet 14 and an air pipe 15
 which is serially connected with an air switch 151, an air adjusting valve
 152, and an air pressure gauge 153. The new oil area 12 is provided with a
 new oil pipe 16 connected therewith, whereas the old oil area 13 is
 provided with an old oil pipe 17 connected therewith. The new oil pipe 16
 and the old oil pipe 17 are controlled by an oil passage switch 18.
 The oil passage switch 18 is connected with a first oil pipe 21 which is in
 turn connected with an oil distributing valve 20. The oil distributing
 valve 20 is connected with the high pressure automatic throttle valve 2
 and a second oil pipe 22 which is serially connected with an oil meter 221
 and an oil filtering bud 222. A third oil pipe 23 is connected with an oil
 pressure gauge 231. A fourth oil pipe 24 is connected serially with the
 high pressure throttle valve 2 and a first three-way valve 2A which is
 connected at one end thereof with an oil replenishing tank 25, and at
 other end thereof with another oil meter 26. The new oil pipe 16 and the
 oil meter 26 are connected via a second three-way valve 2B.
 In operation, the second oil pipe 22 is connected with the oil draining
 outlet of the transmission case of the engine, whereas the fourth oil pipe
 24 is connected with the oil injecting inlet of the transmission case of
 the engine. Thereafter, the engine of the motor vehicle is started,
 thereby resulting in the old engine oil being forced by the power of the
 engine in operation to flow into the second oil pipe 22 and then
 eventually into the old oil area 13 of the low pressure oil cylinder 1 via
 the oil distributing valve 20, the first oil pipe 21, the oil passage
 switch 18, and the old oil pipe 17. The new oil in the new oil area 12 is
 forced into the transmission case of the engine via the new oil pipe 16,
 the second three-way valve 2B, the second oil meter 26, the fourth oil
 pipe 24, and the oil replenishing tank 25. As the oil-changing process is
 in progress, the old oil area 13 of the oil cylinder 1 is eventually
 filled with the old oil which is drained out of the transmission case of
 the engine, thereby resulting in the pressure buildup which cause the high
 pressure automatic throttle valve 2 to open so as to enable the old oil to
 flow through to enter the fourth oil pipe 24, the oil replenishing tank
 25, and the engine, As a result, the pressure equilibrium is attained.
 As shown in FIG. 4, the old oil may be recycled by removing the impurities
 in the old oil. In operation, the new oil area 12 of the low pressure oil
 cylinder 1 is filled with the new oil, whereas the old oil is completely
 drained out of the old oil area 13 such that the old oil is guided through
 the second oil pipe 22, the oil filtering bud 222, the first oil meter
 221, the first oil pipe 21, the oil passage switch 18, the second oil
 meter 26, and the oil replenishing tank 25. The filtered oil is finally
 guided back into the transmission case of the engine.
 As shown in FIG. 5, the old in the low pressure oil cylinder 1 may be
 completely drained out. In operation, air is pumped into the new oil area
 12 of the low pressure oil cylinder 1 via the air pipe 15, thereby causing
 the piston 11 to descend so as to force the old oil in the old oil area 13
 out of the old oil area 13. The old oil is guided through the old oil pipe
 17, The oil passage switch 18, the first oil pipe 21, the second oil pipe
 22, the second oil meter 221, and the oil filtering bud 222. The old oil
 is finally discharged.
 As shown is FIGS. 6 and 7, the present invention is provided with a
 graduation dial 6 for displaying the ratio of the new oil to the old oil
 in the low pressure oil cylinder 1 so as to assist the operator of the
 present invention to understand the status of the oil changing operation.
 The piston 11 of the low pressure oil cylinder 1 is provided at the top
 end thereof with a slide rod 111 connected therewith such that the slide
 rod 111 slides on a slide rail 3 and that the slide rod 111 is connection
 with a connection rod 112 which is fastened at other end thereof with a
 rotary disc 4 of a machine platform 5. The rotary disc 4 is linked with a
 pointer of the graduation dial 6 by a transmission belt or chain. As the
 piston 11 moves up and down, the slide rod 111 ascends and descends
 accordingly to actuate the rotary disc 4 to turn. As a result, the pointer
 is actuated to show the operator the ratio between the new oil and the old
 oil.
 The embodiment of the present invention described above is to be regarded
 in all respects as being merely illustrative and not restrictive.
 Accordingly, the present invention may be embodied in other specific forms
 without deviating from the spirit thereof. The present invention is
 therefore to be limited only by the scopes of the following appended
 claims.