Abstract:
The present invention provides an inexpensive and easily produced method for refurbishing transmission pump assemblies. The method of converting a transmission pump assembly from a first configuration to a second configuration comprises the steps of: a) providing a first configuration transmission pump assembly comprising a pump body and a pump cover, wherein the pump body and the pump cover each have a plurality of fluid passageways formed between worm tracks on at least one side thereof; b) removing a portion of the worm tracks from both the pump body and the pump cover; c) providing at least one insert; d) attaching the at least one insert into a predetermined position; and e) machining the pump cover and pump body to the second configuration.

Description:
TECHNICAL FIELD 
     The invention relates generally to a method of converting the configuration of a transmission pump into a later model year configuration transmission pump assembly. More specifically the invention relates to a method of converting a 1984-1994 General Motors 700 R4 transmission pump assembly into a 1995 or later configuration General Motors transmission pump assembly allowing a low cost replacement transmission pump. 
     BACKGROUND OF THE INVENTION 
     An automotive transmission multiplies engine torque or reduces engine rpm to match varying operating conditions in a manner optimizing engine power and torque. An automatic transmission generally comprises a torque converter, automatic transmission shafts, planetary gearsets providing different gear ratios, planetary holding members or clutches, transmission fluid pump, transmission shafts, hydraulic valves, shift linkage, converter housing, transmission case, transmission fluid pan, and an extension housing. 
     The automatic transmission is generally operated by a hydraulic fluid circuit. Pressure is developed by the transmission fluid pump, sometimes called an oil pump or front pump. The pump draws fluid from the transmission fluid pan and creates hydraulic pressure, which is then directed to other parts of the transmission to fill the torque converter, operate the holding member band and clutch assemblies, control shifting, lubricate the moving parts of the transmission, and circulate the fluid to and from an oil cooler for heat transfer. The pump is driven by the engine typically through driving lugs on the torque converter. When the engine is running, the pump produces power to operate the hydraulic system. 
     General Motors introduced a second generation transmission pump on its model 700 R4 transmission assembly in model year 1984 that remained basically unchanged through model year 1994. The 700 R4, (also designated 4L60E) utilizes a C-Vane type transmission oil pump comprising a pump body, a pump vane assembly, and a pump cover assembly. The 700 R4 transmission has been modified several times over the years. Some of these changes directly affected the compatibility of the transmission pumps between different model years. 
     When a transmission pump fails and needs to be replaced, the vehicle owner typically has a new or remanufactured transmission pump installed. New transmission pumps direct from the original equipment manufacturer (OEM) can be quite expensive. Significant cost savings can be obtained by using a remanufactured part. For example, a salvaged and remanufactured transmission pump from a 1984 model year 700-R4 transmission could be used for the same transmission for 1984-1994 model years. As these are older cars and cover over ten years of production, the number of salvageable transmission pumps are plentiful and comparatively low cost. However due to later model year changes in the transmission, the same pump could not be used for the same transmission of a 1995 model year. The limited number of salvaged transmission pumps from a transmission pump having a run of one or two years makes it virtually impossible to get a remanufactured part, thereby forcing the consumer to pay for a new OEM transmission pump. 
     Therefore, there remains a need in the art for a method of converting an older version of the transmission pump into a configuration compatible with later model year transmission pumps. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide an inexpensive and easily produced method for refurbishing transmission pump assemblies for later model year transmissions. These and other advantages are provided by a method of changing the configuration of a transmission pump assembly from a first configuration to a second configuration, the method comprising the following steps: a) providing a first configuration transmission pump assembly comprising a pump body and a pump cover, wherein the pump body and the pump cover each have a plurality of fluid passageways formed between worm tracks on at least one side thereof; b) removing a portion of the worm tracks from both the pump body and the pump cover; c) providing at least one insert; d) attaching the at least one insert into a predetermined position; and e) machining the pump cover and pump body to the second configuration. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention and developments thereof are described in more detail in the following by way of embodiments with reference to the drawings, in which: 
     FIG. 1 is an exploded perspective view of a typical automatic transmission showing the relative positions of the torque converter and fluid pump; 
     FIG. 2 is an exploded perspective view of a typical vane type fluid pump assembly; 
     FIG. 3 is a plan view of the worm track side of an unmodified pump body; 
     FIG. 4 is a perspective view of the front side of an unmodified pump body; 
     FIG. 5 is a plan view of the worm track side of a modified pump body; 
     FIG. 6 is a perspective view of the front side of a modified pump body; 
     FIG. 7 is a plan view of the worm track side of an unmodified pump cover; 
     FIG. 8 is a plan view of the worm track side of a modified pump cover; 
     FIG. 9 is a plan view of a portion of the worm track side of an unmodified pump body; 
     FIG. 10 is a plan view of the pump body shown in FIG. 9 having portions of the worm track removed; 
     FIG. 11 is a plan view of the pump body shown in FIG. 10 having grooves machined into the floor of the pump body; 
     FIG. 12 is a plan view of the pump body shown in FIG. 11 having inserts attached to change the worm tracks to the modified configuration; 
     FIG. 13 is a perspective view of the cast insert shown in FIG. 12; 
     FIG. 14 is a plan view of a riser ring casting; 
     FIG. 15 is a plan view of a riser ring. 
     FIG. 16 is a plan view of the pump cover shown in FIG. 7 having grooves machined into the floor of the pump body; 
     FIG. 17 is a perspective view of an insert; 
     FIG. 18 is a plan view of the pump cover shown in FIG. 16 having three inserts attached; 
     FIG. 19 is a plan view of the pump cover shown in FIG. 18 which is machined to its final configuration; and 
     FIG. 20 is a side elevational view of the pump cover. 
     FIG. 21 is a listing of the steps of the method of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 illustrates a partial exploded view of a typical automatic transmission assembly  110 . The torque converter  112  is housed in a converter housing  114 . Fluid pump assembly  116  is housed within a transmission case  118 . Extension housing  120  is attached to an end of the transmission case  118  opposite the converter housing  114 . Fluid pan  122  is attached to the bottom of transmission case  118 . The transmission assembly  110  also comprises a input shaft  124  which is driven by the engine (not shown). 
     Referring now to FIG. 2, a typical 1984 and on C-vane type fluid pump assembly  126  as used in a GM 700-R4 transmission is shown in an exploded perspective view. The major components of the fluid pump assembly  126  are the pump vane rotor assembly  128 , pump slide  130 , pump body  132 , pump stator, or cover  134 , and stator shaft  136 , shown herein attached to pump cover  134 . The pump body  132  and pump cover  134  each have corresponding fluid passageways  137  also referred to as worm grooves, separated from each other by passageway walls  160 , or worm tracks. Some of the passageways  137  have holes designed for fluid passage which allow fluid flow in a particular direction or that can open or close on demand. It is noted that the configuration shown is a 7-vane fluid pump. The number of vanes was increased to 10 staggered vanes in the 1986 model year, and then 13 vanes in 1997 model year. 
     Pump body  132  is shown in FIGS. 3 and 4, with FIG. 3 showing a plan view of the worm track side  138  of pump body  132  and FIG. 4 showing a perspective view of the front side  140  of the pump body  132 . A 10 vane rotor assembly  228  and associated pump slide  230  are shown mounted in the central recess of the worm track side  138  of pump body  132 . A seal drain passageway  152  is also partially shown as it is contiguous through the side of the pump body (not shown). A mounting register face  142  is shown machined into the radial outward portion of the front side  140  of the pump body  132 . Mounting bolt holes  144  are positioned about the mounting face  142 . 
     As previously mentioned, a series of changes were made to the fluid pump assembly  126  starting with the 1995 model year. These changes primarily involved changes to the configuration of the fluid passageways  137  to incorporate pulse width modulation. These changes were intended to help the transmission  110  run more smoothly and eliminate pressure spikes from the transmission pump assembly. Referring now to FIG. 5, a plan view of the worm track side  138 ′ of a 1995 and on model year configuration pump body  132 ′ is shown. The fluid passageways  137  that are modified are highlighted by being shown as darkened areas  146 . In addition, the seal drain passageway  152  was enlarged to improve fluid flow. Changes in the 1996 model year involved primarily the addition of risers on the torque converter side of the pump body. Referring now to FIG. 6, a perspective view of the front side  140 ′ of a 1996 and on model year configuration pump body  132 ″ is shown. Risers  148  are positioned about the circumference of register face  142 ′. The risers  148  were added to center the pump assembly  116  in the bell housing (not shown). 
     Referring now to FIG. 7, a plan view of the worm track side  150  of an unmodified pump cover  134  is shown. The fluid passageways  137  of the pump cover were also modified in the 1996 model year. A plan view of the worm track side  150 ′ of a modified pump cover  134 ′ is shown in FIG.  8 . The fluid passageways  137  that are modified are highlighted by being shown as darkened areas  146 . 
     The method  10  of converting the configuration of a transmission fluid pump assembly  116  in accordance with the present invention will now be described in detail and are listed for reference in FIG.  21 . The initial step is providing  12  a 1984-1994 model year transmission pump assembly  116  for a 700-R4 transmission assembly  110 . While a new OEM pump assembly  116  could be used, it is more economical to use a salvaged used pump assembly  116 . 
     The next step is to disassemble  14  the used, transmission pump core  116  into its three major components, the pump body  132 , pump cover  134 , and stator shaft  136 . The components are then degreased  16 . The modification of the pump body  132  is described next. 
     Transmission pumps are subjected to significant heat/cooling cycles during their operation and a used pump  126  may be slightly warped. Accordingly, the mounting register face  142  of the front side  140  of the pump body  132  is cut  18  on a lathe to remove any warpage due to service. The seal drain passage  152  is then machined  20  to enlarge the passageway  152  to the modified pump specifications. The pump body  132  is then bead-blasted  22  to clean up the surfaces for machining. 
     Referring now to FIGS. 9-13, the modification of the fluid passageways  137  is shown. FIG. 9 shows a partial plan view of a portion of an unmodified pump body  132 . The pump body is then placed on a CNC mill and portions  154  of the worm track wall  160  are cut away  24  as best shown in FIG.  10 . Special care is taken to the radius on the four sides created in the cavity. The next step is to cut  26  grooves  156 ,  157  into the floor  158  of the pump body  132  which corresponds to the localized changes to the worm track wall  160  of the 1995 model of the pump body  132 ′. The grooves  156 ,  157  are shown in dotted lines in FIG. 11 Referring now to FIGS. 12 and 13, insert  170  is created  28  to provide the new configuration of the worm track walls  160  and is generally shaped like the number “2”. The insert is made as an aluminum casting, however, it is not intended to be limited as such and may be machined or formed by any suitable means. The insert  170  is secured  30  within the corresponding groove  156  by an industrial adhesive  168  which is applied to the bottom and sides of the insert  170 . The industrial adhesive  168  may be any suitable adhesive which will permanently hold the insert  170 , even when post machining work is being done on the insert. An additional piece of aluminum  172  is secured  32  with industrial adhesive  168  within groove  157  to duplicate a second modification to the worm track walls  160 . The smaller insert  172  is typically oversize and then machined  34  (after the adhesive is dried) to its final dimensions to correspond with the specification of the modified pump body  132 ′ as shown in FIG.  12 . 
     After the adhesive is dried, the pump body  132 ′ is placed on a lathe. The register face  174  and the pump assembly recess face  176  are cut  36  to a tolerance of plus or minus two tenthousandths (0.0002) of an inch. The slide  230 , rotor vane assembly  228 , and other associated parts are installed  36  on the pump body. The pump body is now configured as 1995 model year modified pump body  132 ′ (see FIG.  5 ). 
     As previously discussed with relation to FIG. 6, the pump body  132 ′ was modified in the 1996 model year. For 1996 and on model years, the method of conversion  10  further comprises the addition of a riser ring  180 . The riser ring  180  is produced as follows. An aluminum ring  180  with risers  148  generally corresponding to the dimensions of the mounting register face  142  of the front side  140  of the pump body  132 , is cast  40  in a mold (a ring could also be machined but would be more costly if a significant number of pumps are being remanufactured). The as-cast ring  180  is placed on a lathe and the bottom  182  of the ring  180  is cut  42  flat. The outside diameter  184  and the inside diameter  186  are hand filed  44  to assure that it fits in a fixture (not shown). The fixture is a device used to hold  46  the ring  180  under the pump body  132 ′ in a manner that the bolt holes  144  in the pump body are used as guides to drill  48  the mounting holes  144 ′ in the ring  180 . Because these bolt holes  144  vary slightly from one pump to another, the pump body  132 ′ used to drill the holes  144 ′ is mated to the particular riser ring  180 . Industrial adhesive  168  is placed on the bottom face  182  of the ring  180  and the bottom face  182  is attached  50  to the register face  142  of the front side  140  of the pump body  132  such that the mounting holes  144 ,  144 ′ are properly aligned. 
     After the adhesive has dried, the pump body  132  is placed in another special set of jaws on the lathe. The outside diameter of the riser ring is cut  52  to match the outside diameter of the pump body. The top face  183  of the ring is then cut  54  so that the thickness of the pump body  132  with the ring installed meets the dimension specification of the modified pump body  132 ′. 
     Referring again to FIGS. 7 and 8, the pump cover  134  must also be modified in a similar manner as the pump body  132  to convert it to the modified pump cover  134 ′ configuration. Referring now to FIGS. 16-20, the modification of the fluid passageways  137  on the pump cover  134  is shown. FIG. 16 shows a partial plan view of a portion of pump cover  134 . Hole  188  is plugged  56  with an aluminum rivet  192 . Grooves  194 ,  196 , and  198  are cut  57  into the floor of the pump cover  134  to allow three inserts to be installed. Although not shown, portions of the worm groove walls may also be milled to allow additional room for installation of the inserts. Referring now to FIGS. 17 and 18, cast aluminum insert  190  is created  58  to provide portion of the new configuration of the worm track walls  160  and is generally shaped like the letter “L”. A second insert  200  is provided  60  and machined as a one inch square piece of aluminum, {fraction (3/16)}″ thick, with full radius on two sides. A third insert  202  is also provided  62 . The inserts  190 ,  200 ,  202  are attached  64  to the pump cover  134  with a suitable industrial adhesive. After the adhesive has dried sufficiently, the pump cover  134  is then milled  66  at locations  204  to the modified pump cover configuration  134 ′ as shown in FIG.  19 . 
     The pump cover  134 ′ is placed in the lathe and the back side, the side opposite the worm track side  138 , is cut  68  parallel to the worm track side  138 . 
     Referring now to FIG. 20, the three major holes  206 ,  207 ,  208  are centered, drilled, and reamed  70  to the larger hole specifications of the modified pump cover  134 ′ to a tolerance of plus or minus 0.0002″. The stator shaft  136  is then installed  72  through pump cover  134 ′ and it is placed back on the lathe. The worm track side  138 ′ of pump cover  134 ′ is faced  74  and it is now ready for assembly  76  with pump body  132 ′. 
     Although not specifically discussed several additional holes are enlarged and/or plugged to finalize the conversion. These operations are omitted as they are common machining procedures understood by those in the art. 
     The present invention provides a method of conversion of a transmission pump without requiring any welding. It is contemplated that the inserts could be replaced by direct welding in the locations to be modified and then machined to the proper configuration. However, the welds sections may have problems with porosity that even peening of the weld areas may not solve. In addition, the high temperatures involved in the welding process may warp the pump cover and the pump body. 
     The present invention shows a particular transmission pump assembly used in a General Motors application. It is contemplated that the method of the present invention could easily be adapted to be used to convert other transmission pump assemblies that have been changed by the manufacturer under similar conditions. 
     Although the present invention has been described above in detail, the same is by way of illustration and example only and is not to be taken as a limitation on the present invention. Accordingly, the scope and content of the present invention are to be defined only by the terms of the appended claims.