INFINITELY VARIABLE GEAR TRANSMISSION WITH MICROPROCESSOR

CONTROL, for installing on motor vehicles, comprising of a differential gear unit, Hydraulic Speed Control Unit, an Epicyclic gear unit, an Electrical cum Electronic Control Unit and a microprocessor unit The Equipment basically consists of a Differential gear unit which includes a pair of spiral bevel gears, 4 pinions, a pair of helical gears fixed on the output shafts on either side, and a hydraulic gear pump on either side driven by the output shafts. The drive from the engine received through the pair of Bevel gears, passes through the differential pinions and communicated to the Epicyclic gear unit through the pair of helical gears fixed on the output shafts of the differential gear unit The Right side helical pair is connected to the sun gear and the left side helical pair is connected to the planet carrier of the Epicyclic gear unit. The annulus of the Epicyclic gear unit is connected to the vehicle.

The function of me hydraulic unit is to control the rotation of the differential output shafts, to obtain the appropriate output speed from the Epicyclic gear unit The function of the Electrical cum Electronic Circuit is to operate the various control valves in the Hydraulic circuit, in order to direct the fluid flow in the right direction. The basic function of the Microprocessor unit is to adjust the flow control valve in the Hydraulic circuit to regulate the vehicle speed.

The Invention is more clearly described below with reference to the accompanying drawings. In sheet no: 1, figure: 1 is a sectional drawing of the differential gear unit. Part 1 is the Bevel gear attached to the differential body Part 2 is the revolving pinion; Part 3 is the differential body; Part 4 is the driven Helical gear on right side; Part 5 is the driving helical gear on right side; Part 6 is the gear pair for the Hydraulic pump on right side; Part 7 is the pinion attached to the output shaft; Part 8 is the spiral bevel gear for the incoming drive; Part 9 is the gear pair for the hydraulic pump on left side; Part 10 is the driving helical gear on left side; and Part 11 is the driven helical gear on the left side. In sheet no: 2, Figure 2 is the 3- Dimensional drawing of the differential gear unit In sheet no: 3, Figure 3 is the sectional drawing of the Epicyclic gear unit. Part 1 is the sun gear attached to part 7, part 2 is the top planet gear, part 3 is the planet carrier attached to part 6, part 4 is the annulus attached to part 10, part 5 is the bronze bush for part 10, part 6 is the main shaft, part 7 is the input gear connected to the part 4 in Figure: 1, part 8 is the bottom planet gear, part 9 is the bush connected to the planet carrier and the main shaft, part 10 is the out put gear fixed on the annulus and connected to the vehicle; and part 11 is the input gear fixed on the main shaft and connected to the part 11 in Fig: 1 In sheet no: 4 figure 4 is the 3 dimensional view of the epicyclic gear unit In sheet no: 5, Figure 5 is the Hydraulic circuit diagram. Part 1 is the delivery line for the right side (RS) gear pump. Part 2 is the solenoid valve V6 in the alternate delivery line of the left side (LS) gear pump. Part 3 is the solenoid valve V5 in the alternate delivery line of R.S. gear pump. Part 4 is the solenoid valve V4 in the main delivery line of R.S. gear pump. Part 5 is the solenoid valve V3 in the main delivery line of LS. gear pump. Part 6 is an orifice T1 in the main delivery line. Part 7 is the orifice T1 fixed in the alternate delivery line of R.S. gear pump. Part 8 is the hydraulic oil reservoir. Part 9 is the suction line for the gear pumps. Part 10 is the orifice T3 fixed in the alternate delivery line of L.S. gear pump. Part 11 is the alternate delivery line of L. S. gear pump. Part 12 is the L-S. gear pump. Part 13 is the solenoid valve V2 in the suction line of the L.S. gear pump. Part 14 is the solenoid valve V7 separating the suction tine of L.S. gear pump and the delivery line of the R. S. gear pump. Part 15 is the line connecting the delivery of the R.S. gear pump to the suction of the L. S. gear pump. Part 16 is the solenoid valve V1 fixed in the return line of R.S. gear pump. Part 17 is the R.S. gear pump. Part 18 is the solenoid valve V8 for diverting the fluid for microprocessor control. Part 19 is the flow control valve with variable orifice governed by the microprocessor. Part 20 is the rack attached to the Hydraulic piston. Part 21 is the pinion attached to the valve spindle and driven by the rack. Part 22 is the Hydraulic Cylinder for microprocessor control. In sheet no: 6, Figure 6 is the same Hydraulic circuit diagram without the identification numbers.

In sheet no: 7, Fig: 7 shows the curve for the Engine RPM versus the vehicle speed. The normal forward movement of the vehicle is represented by the curve ABCD. The curve OA represents the idle portion; AB represents the low gear portion; BCE represents Direct Drive and CD represents over drive. The normal reverse is represented by the curve AR. The curve FC represents the forward movement in High gear, and the curve FR1 represents the reverse movement in high gear.

In sheet no: 8, Fig: 8 represents the Electrical cum Electronic Control Circuit to change the direction of the fluid flow in the Hydraulic circuit P represents the parking position. F represents the normal forward movement. HF represents the high gear forward movement and HR represents the high gear reverse movement R represents the normal reverse movement CC represents the position for microprocessor control. C1 is a microprocessor controlled switch to change over from gear drive to direct drive and vice versa. S1, S2, S3, S4, S5, S6, S7 and S8 are change over switches actuated by speed sensors at the rated speed and remains actuated above the rated speed V1 to V8 are Solenoid valves which normally remain closed, and open on energizing. M1 is a manually operated switch to maintain direct drive at slow speed. M2 is a manually operated switch to avoid over drive. In sheet no.9, figure 9 is the general assembly of the equipment, and is for inclusion in the front page of the Patent Publication. When the power from the Engine is transmitted to the differential unit through the Bevel gear pair, the output shafts of the unit start rotating. The rotation of the output shafts follows the formula 2N = N1 + N2 - (1) where as N is the Engine speed, N1 is the right side output shaft speed and N2 is the left side output shaft speed. While the vehicle control lever is in the park position the valves V1 V2 and V3 are open as shown in figure 5 and therefore the hydraulic pump on RS sucks the oil and pumps the oil back into suction line; The LS pump sucks the oil and deliver back into the reservoir, as shown in figure 5. Therefore the output shafts are free to rotate at any speed In the case of Epicyclic gear if X 1 is the speed of the Sun gear, X2 is the speed of planet carrier and X is the speed of Annulus, X 1 = 4.5 X2 - 3.5 X Formula (2). (The annulus is the output gear connected to the vehicle) where as (Z1 + Z2) / Z1 = 4.5 and Z2 / Z1 = 3.5 •

Z1 = No. of teeth on Sun gear = 24 Z2 = No. of teeth on annulus = 84 If the Engine Speed is 1500, on applying formula (1) N1 will be equal to 2455 and N2 will be equal to 545. Similarly if the Engine speed is 2000, N1 will be equal to 3273 and N2 will be equal to 727 .If the Engine speed is 3000 N1 will be 4909 and N2 will be 1091.

In all these cases applying the value of X 1 and X2 in formula (2), the output speed of Epicyclic gear, i.e. the value of X will be zero; (N1 = X 1 and N2 = X2); and therefore the vehicle will be at stand still when the control lever is in the `P' position.

When the vehicle control lever is in F (Forward Position), till the Engine speed is raised to 1500 the same situation will continue. At 1500 the Engine speed sensor will give a signal to the S1 switch to operate valves V4, V2 and V3 of the Hydraulic circuit Since V2 and V3 are open the LS gear pump is freely running; but the RS gear pump is pumping through the valve V4 and the orifice T1 (Part no.6 in figure 5) which restricts the speed of the RS pump to 2454 RPM. This results in a reduction of the vehicle speed. It can be noted from formula (2), that the tendency of the right side pump will be to run faster and the LS pump to run slower, during the forward movement of the vehicle. When the right side pump is locked at 2454, it will continue to run at the same speed at any engine speed since 2N = N1 + N2. The output speed of the Epicyclic gear, corresponding to 1500 to 2454 (Engine Speed) has been given below in Table I. Example: When Engine Speed is 2000, the R. S. output shaft speed is 2454. Appying Formula (1) 2N = N1 + N2 2 x 2000= 2454 +N2 Therefore N2 = 1546 Applying Formula (2) X1 = 4.5 X2 - 3.5 X X1 = N1 & X2= N2 Therefore 2454 = 4.5 x 1546 - 3.5X X= 1286

TABLE I

The output speed is ranging from 0 to 2454, to provide enough starting torque for the vehicle during the initial start At 2454 the speed sensor will give a signal to S2 switch to operate the valves V3 and V7 of the hydraulic circuit. In this condition the delivery of the RS Pump is directed to the suction side of the LS pump. Since R.S pump is always trying to run faster and the LS pump is always trying to run slower, the result will be both the pumps will be running at the same speed. This means both LS and RS output shafts and the Engine will run at the same speed; the output of the Epicyclic gear will also be the same as shown below. X1 = 4.5 X2 - 3.5 X Since X1 = N1 = N2 = X2 Therefore X1 = 4.5 X1 - 3.5 X - 3.5 X 1 = - 3.5 X and X= X1 Therefore At the speed of 5250, L.S and RS. output shafts, and also the Epicyclic gear output will be 5250. In this condition the Vehicle is in direct drive. At 5250 (Engine Speed) the speed sensor will give a signal to S3 switch to operate the valves V2, V3 and V5. Since V2 and V3 are open the LS. Pump will operate freely; but the R.S. pump will deliver through the alternate delivery line through the valve V5 and orifice T2 (part no.7 in figure 5) which restricts the Speed of the RS pump to 5250. The speed of LS and RS output shafts and Epicyclic gear output at various Engine Speeds have been given below. (Table E) Table II

Ex: At 6000 Engine Speed. 2N = N1 + N2 (1) 2 x6000= 5250 -I- N2

Therefore N2 = 6750 N1 = X1 & N2= X2 X1 = 4.5 X2 - 3.5 X - — (2) 5250 = 4.5 x 6750 -3.5 X

Therefore X = 7178 In this condition the vehicle is in over drive. There is an option here to avoid over drive in which case switch M2 has to be manually actuated. On return the vehicle speed will follow the same path till 5250 Engine Speed. Below 5250 Engine Speed, S3 will be deactuated and the vehicle will switch over to Direct Drive with the valves V3 and V7 opened. Below 2454 S2 will be deactuated; S1 will take over to open V4, V2 & V3; and the vehicle will follow the speed as already given in Table 1. There is an option here to avoid gear drive between 1500 and 2454 in which case M1 has to be manually actuated The vehicle will now continue in direct drive till the control lever is shifted to park position. For the Reverse drive the control lever has to be shifted to R' position. At 1500 speed the speed sensor will operate S7 and Valves V2, V6 and V1 will open. Since V1 is open R.S. pump will be operating freely; but L.S. pump will suck the fluid through valve V2 and deliver through orifice T3 (Part 10 in Figure 5) and the speed of L.S. pump will be limited to 546. The vehicle will now move in reverse as given below. (Table III). It may be noted from the formula that during reverse, the L.S. Pump will always try to run at higher speed and the R.S. pump will try to run at slower speed.

Table III

Example: At 2000 Engine Speed X1 = 4.5 X2 - 3.5 X 3454 = 4.5 x 546 - 3.5 X Therefore X= -285. There is an option for High Torque forward drive. In this case the control lever has to be brought to HF position, where in at Engine Speed 3208, the sensor will give a signal to S4 to operate V2, V3 & V5. Since V2 & V3 are open the L.S. pump will operate freely. The R.S. pump will operate through the alternate delivery line and the speed will be limited to 5250. The vehicle speed will be as shown in Table IV. Below 3208, S4 will be deactuated and the vehicle will move to neutraL In this position the vehicle can have higher torque. This drive is basically meant for high ranges. Example: At 4000 Engine speeds, RS. Output shaft speed is 5250. Applying formula (1) 2N = N1 + N2 Therefore 2 x 4000 = 5250 + N2 Therefore N2 = 2750. Applying formula (2) X1 = 4.5X2 - 3.5X N1 = X1 & N2 = X2 Therefore 5250 = 4.5 x 2750 - 3.5X Therefore X = 2035

Table IV

There is also an option for High torque reverse movement. TMs drive is also intended for high ranges. In this case the control lever has to be brought to HR. At 3150, S5 will be actuated to open V2, V3 and V5 as exactly in the case of HF. At 3200, S6 will be actuated to open Vl, V2 & V3. Between 3150 and 3200 the vehicle will move in reverse as shown in Table V below.

Table V

Ex: - At 3200 speed N1 = 5250 N2 = 1150 X1 = 4.5 X2 - 3.5X

Therefore X = - 21

The System is also provided with an option, wherein the vehicle speed will be controlled by the Microprocessor unit to meet the required torque at the exact time during the forward drive. (Please see item 6 in Figure 8). For mis facility of "Drive by Wire", the vehicle control lever has to be brought to position CC. Please also see the flow control valve with variable orifice (item 19 in Figure 5) driven by the Hydraulic Piston controlled by the microprocessor, through the rack and pinion (Item 20 and 21 in Figure: 5) In position CC, valves V1. V2 and V3 will be open and the vehicle will be in neutral. The microprocessor will now come into action, set the flow control valve so as to limit the Right side output shaft speed to 3000. When the Engine Speed is increased to 1833, S8 will be actuated to open valves V2, V3 and V8 so that the flow will be diverted through alternate route on the extreme left (Please see figure: 5). The vehicle will now start moving as given below.

TABLE VI

During the speed range from 1833 to 3000 the microprocessor installed in the vehicle will continuously receive the data on the accelerator pedal position, the suction pressure of the Engine, the Engine temperature, the RS output shaft speed and the engine speed through sensors. If the Engine speed and the suction pressure matches with the accelerator pedal position, and the temperature is steady, the indication is that the Engine produces enough torque required for the vehicle. On the other hand, if there is a drop in suction pressure along with the engine speed in relation to the accelerator position, the microprocessor will give a signal and the hydraulic piston will drive the flow control valve in anticlockwise direction to open more and to increase the speed limit for the R.S. output shaft till sufficient Torque is made available. At 3000 speed, if sufficient torque is available, the Hydraulic Piston drives the flow control valve and set the valve at 3000, if not already at 3000. If the conditions continue to remain steady the microprocessor unit gives a signal to C1 to open V3 and V7. The vehicle will now move in Direct Drive. From 3000 to 5250 speed and also during the return to 1833 speed, the system will continuously monitor the torque level. At any time if sufficient torque was not found available, the system gives a signal to C1 to open V2, V3 and V8. The hydraulic piston will now drive the flow control valve to open more till sufficient torque is made available, i.e. the suction pressure and the Engine speed matches with the accelerator pedal position and the Engine Temperature is steady. When conditions stabilize, the system sets the flow control valve equal to the Engine Speed; If the conditions continue to remain steady it gives a signal to C1 to open valves V3 and V7 so that the vehicle will move in direct drive. The corrective action by the microprocessor unit will not continue beyond 5250 and the maximum speed limit will not be more than 150% of the Engine Speed. Beyond 5250 speed, the vehicle will move in over drive as in Table II.

The idle speed range and the speed limit settings of the Differential output shafts can be selected depending on the type of vehicle and the users preference. The Electrical cum Electronic circuit can be replaced by a microprocessor unit, in which case the control lever also can be eliminated by 6 interlocked keys. Instead of orifices T1, T2 and T3, the system can be provided with flow control valves with variable orifice (Item 19 in figure 5 ) which can be actuated by microprocessor controlled hydraulic piston and speed sensors, as explained earlier, in order to have the accurate speed settings, and the exact output speed as well. The Entire drive transmission can be controlled by a 32 bit 40 MHz microprocessor.