Control arrangement for an automatic, electrohydraulically controlled transmission

The invention concerns a control arrangement for an automatic electrohydraulically controlled transmission. In order to reduce expenditure on parts and assembly, the hydraulic control system and electronic control system are mounted directly adjacent each other and plug-in connections are provided between the solenoid valves of the hydraulic control system and the electronic control system. The hydraulic control system (20) substantially comprises two duct panels (28,30) in which control ducts, piston slides and solenoid valves (not shown) are disposed for controlling the conical plates and couplings of the transmission. The pressurized hydraulic fluid is fed directly into these duct panels from the pump (29). The electronic control system (22) has a single central connection (36) which is secured in the transmission housing cover (42) by an annular seal. Rotational speed sensors for the transmission shafts and temperature and pressure sensors are integrated into the control unit.

The invention pertains to a control arrangement for an automatic,
 electrohydraulically controlled transmission, especially for motor
 vehicles.
 In such automatic transmissions in motor vehicles, the hydraulic control,
 as well as various sensors for pressure and rpm, are integrated into the
 transmission and are connected via corresponding lines to the electronic
 control unit that is located outside of the transmission. This leads to
 very high assembly and parts costs, as well as a certain vulnerability to
 malfunctions due to possible line breaks.
 The object of the invention is to propose a reduced-cost, easy-to-assemble,
 highly reliable arrangement of the hydraulic and electronic controls of
 the automatic transmission.
 According to the invention, it is proposed that the hydraulic control and
 electronic control be built right next one another, in which case plug
 connections are provided between the solenoid valves of the hydraulic
 control and the electronic control. This can considerably reduce the line
 costs because the plug connections can be hard-wired in the electronic
 control unit or integrated into circuit boards and directly connected to
 the solenoid valves or their plug connectors.
 Moreover, sensor arms can extend downward from the electronic control that
 ensure contactless sensing of the shaft-mounted transducer wheels of the
 input and output shafts of the automatic transmission past the hydraulic
 control. This ensures that the rpm sensors are also directly incorporated
 into the electronic control unit.
 As a logical enhancement, at least one pressure sensor can also be arranged
 right in the electronic control unit that is connected to the control duct
 of the hydraulic control that is to be sensed in a fluid-tight manner,
 e.g., via a plug connector with a sealing ring.
 With the aid of an integrated temperature sensor, the temperature of the
 hydraulic fluid can also be monitored in order, for example at low
 temperatures, to trigger a warm-run program and at excessively high
 temperatures to trigger intervention into the switching time of the
 starter coupling and/or power-reducing run programs in the electronic
 control.
 At the electronic control there is preferably a single electric central
 connector through which the vehicle-specific control parameters, such as
 engine management, demand for power, etc. can be input and transmission
 data can be output. When the automatic transmission is being assembled or
 disassembled, with respect to the electric control it is therefore
 necessary only to close or detach one plug connector.
 To ensure better accessibility of the hydraulic and electronic controls,
 these controls can be surrounded by a transmission cover, in which case a
 penetration in the cover tightly encases the central connection and makes
 it accessible from the outside.
 To further simplify the assembly process, on the electronic control there
 can be another sensor that works directly together with a position
 transducer of a manually operated selector shaft that is swivel-mounted in
 the transmission. Thus, the shifting commands can also be directly input
 into the electronic control in a way that facilitates assembly. To ensure
 ease of production, the position transducer is preferably made of plastic,
 in which case for each selector position a magnetic element can be tied in
 to ensure contactless shift position sensing using the Hall effect system.

Section 10, which is shown in FIGS. 1-4, is part of an electrohydraulically
 controlled CVT transmission with a drive shaft 12 and a driven shaft 14,
 on which drive and driven conical plates that can be adjusted with regard
 to their effective diameters and a strap means, e.g., a link conveyor, are
 arranged in order to ensure infinitely variable transmission ratio
 modification and contain the transmission component for reversing
 rotational direction (reverse gear) and hydraulically activated couplings
 for starting and changing direction. These gear components, not shown, are
 of a known conventional type.
 At the end opposite the transmission input and output, housing 16 of the
 transmission ends in a front transmission flange 18 on which (cf. FIG. 2)
 a hydraulic pump 29, a hydraulic control 20, and an electronic control 22
 are mounted right next to each other and are secured in place with the aid
 of screws 24 and alignment pins, not shown. In this case the hydraulic
 pump 29 lies in a recessed area 27 of the transmission flange 18, is
 screwed directly to the hydraulic control 20, and is driven on the
 transmission side via shaft 26, which is partially shown.
 The hydraulic control 20 consists essentially of two duct plates 28, 30 in
 which control ducts, pistons slides, and solenoid valves (not shown) for
 controlling the conical plates and couplings of the transmission are
 arranged in a known way and into which the pressurized hydraulic fluid is
 injected directly from pump 29.
 The electronic control 22, which is mounted directly on the hydraulic
 control 20, in a known way contains a CPU with the logical connecting
 circuits as well as characteristic stores for the selector programs and
 corresponding output amplifiers to control the solenoid valves in order to
 ensure hydraulic control of the transmission, in which case the
 vehicle-specific parameters such as engine management, demand for power
 (gas pedal position), etc., are fed by the vehicle through a central
 connector 36, in the form of a jack with the corresponding plug contacts,
 that is provided at the plate-like electronic control 22 and transmission
 signals are output (for instance, speed signal, monitoring signals,
 diagnosis, etc.).
 In this case the central connector 36 extends via a ring-shaped seal 38
 through a penetration 40 in a cover 42 that encases the hydraulic and
 electronic controls 20, 22. In turn, cover 42 is screwed to transmission
 flange 18, with a seal between them.
 The electronic control 22 also has a chip 43 as a temperature sensor (cf.
 FIG. 4) which monitors the temperature of the hydraulic fluid. This allows
 quick, temperature-dependent intervention into the transmission control in
 order to trigger warm-run programs at, e.g., low temperatures (inputting
 shorter transmission ratios=higher engine rpm) or at high temperatures to
 trigger shorter coupling engagement times or to trigger run programs or
 engine intervention actions that reduce the load on the transmission.
 In the transmission housing 16 a manually operated selector shaft 44 (cf.
 FIG. 4) is also swivel-mounted via a gear selector lever (not shown),
 whereby said selector shaft activates the catch 52 of a parking brake (not
 shown) of the transmission via a downward-extending arm 46 and a rod
 assembly 48 with a taper adapter 50. A spring-mounted safety arm 53 of
 selector shaft 44 holds the end 51 of rod assembly 48 that is bent at a 90
 degree angle in the corresponding bearing bore 49 of arm 46. When rod
 assembly 48 is assembled, the spring-mounted arm 53 is to be raised
 accordingly until the bent end 51 can be forced into the bearing bore 49.
 Another downward-pointing arm of the selector shaft 44 activates a selector
 slide (not shown) of hydraulic control 20.
 Finally, the selector shaft 44 has a plastic-encased position transducer 56
 which works together with a catch 60 that is pre-stressed by a spring 58
 and in which a magnetic element 62 is embedded for each selector position
 (for example, the plastic can contain iron oxide powder, and the
 corresponding locations can be permanently magnetized locally).
 Magnetic elements 62 ensure the contactless sensing of the selector
 positions of selector 44 based on the Hall effect, in which case a
 correspondingly shaped Hall sensor 64 (cf., in particular, FIG. 3) extends
 downward from the electronic control 22.
 Additionally, there are arm-like rpm sensors 66, 68 which extend from the
 electronic control 22 past the hydraulic control 20 into the transmission
 housing 16 and which directly sense the rpm of these shafts with
 transducer wheels 70, 72 that are directly attached to the drive and
 driven shafts 12, 14. This can be achieved in a known way using the
 induction or Hall effect process.
 The connection wall 74 (FIG. 4) of the electronic control 22 that faces
 toward the hydraulic control 20 also has cooling ribs 76 that are in a
 recessed area and is flushed and cooled by the hydraulic fluid via duct
 openings, not shown, in the hydraulic control 20. The chip 43 or the
 temperature sensor can also be arranged in the electronic control 22 at
 this connection wall 74. A ring-shaped projection 78 ensures that a
 pressure sensor 80 that is integrated into the electronic control 22
 connects directly to the adjacent hydraulic control 20, in which case the
 projection 78 that has a sealing ring 82 extends tightly into a hole (not
 shown) that empties into the control duct to be sensed. The pressure in
 this control duct can thus be picked up directly via the pressure sensor
 80 and processed accordingly in the electronic control. Although only one
 pressure sensor 80 is shown, multiple pressure sensors can also directly
 sense multiple control ducts.
 Furthermore, connection wall 74 has electric plug connectors 84, 86 via
 which the solenoid valves, not shown, of the hydraulic control 20 can be
 electrically connected directly to the electronic control 22.
 In order to secure the sensors 64, 66, 68 that extend downward from the
 electronic control 22 precisely relative to transducer wheels 70, 72 and
 relative to position transducer 56, at the free ends of the sensors are
 pins 88, which extend into corresponding holes 90 in the transmission
 flange 18.
 The connection of the hydraulic control 20 to the transmission is provided,
 on the one hand, in order to control the conical plates and the infinitely
 variable transmission ratio via ducts or ring-shaped ducts 92, 94 (cf.
 FIG. 1, drive shaft 12) in the drive and driven shafts 12, 14 in which
 case pipe sockets 96, 98 that extend downward from the hydraulic control
 20 are inserted into these ducts 92, 94 with sealing piston rings 100
 between them; because of the piston rings 100 that are used, the
 components that are to be sealed can turn relative to one another.
 On the other hand, to ensure the hydraulic supply of the couplings and, if
 necessary, to hook up a hydraulic pump, supply lines 102, 104, 106 that
 run freely in the transmission housing 16 are provided that are inserted
 into receptacles that are provided in the transmission housing 16 and
 extend them toward the hydraulic control 20, in which case a ring-shaped
 sealing sleeve 114 that is mounted on each of supply lines 102, 104, 106
 and that has an outer clamping sleeve 113 and an elastic sealing ring 115
 with radially and axially extended sealing lips ensures a tolerance-safe
 seal between the connection surfaces of the hydraulic control 20 and the
 receptacles 108, 110, 112 in the housing and supply lines 102, 104, 106.
 As the drawing shows, all sealing and plug connections are arranged
 parallel to the drive and driven shafts 12, 14, so that, simply by
 mounting the possibly already pre-mounted control block from the hydraulic
 control 20 and electronic control 22 and then attaching with screws 24,
 all hydraulic and electrical connections and plug-ins are made inside the
 transmission. After the cover 42 is mounted, the only thing to do is to
 connect the vehicle-side central plug to the corresponding central
 connector 36.
 The invention is not restricted to the embodiment described above. Thus,
 for example, instead of a CVT transmission it is also possible to use an
 automatic step reduction gear, for example, a planetary gear system.