WO2018178812A1

WO2018178812A1 - Servo transmission system

Info

Publication number: WO2018178812A1
Application number: PCT/IB2018/051886
Authority: WO
Inventors: Thammineni Subbaiah CHOWDARY
Original assignee: Chowdary Thammineni Subbaiah
Priority date: 2017-04-01
Filing date: 2018-03-21
Publication date: 2018-10-04

Abstract

The present disclosure relates to a transmission system comprising a Positively Infinitely Variable (PIV) drive unit 108 to infinitely vary speed of at least a pair of driving wheels of an automobile, and a servo mechanism comprising a differential unit 104 and at least one hydraulic accumulator 102 configured to modulate gear ratio of the PIV drive unit 108 until torque on a first bevel pinion gear 122 of the differential unit 104 is slightly less than torque on a second bevel pinion gear 130 of the differential unit 104, wherein the servo mechanism senses speed and torque differences between the first bevel pinion gear 122 and the second bevel pinion gear 130 and corrects gear ratio of the PIV drive unit 108.

Description

SERVO TRANSMISSION SYSTEM

TECHNICAL FIELD

[0001] The present invention relates generally to automatic transmission of automobiles, and more particularly to transmission systems capable of infinitely varying speed and torque at driving wheels of an automobile.

BACKGROUND OF THE INVENTION

[0002] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.

[0003] An Automatic Transmission (also commonly referred to as "self-shifting transmission", "n-speed automatic" (where n is number of forward gear ratios), or "AT") is a type of automobile transmission that automatically changes gear ratios as the automobile moves, freeing the driver from having to shift gears manually. Like other transmission systems in automobiles, Automatic Transmission allows an internal combustion engine, best suited to run at a relatively high rotational speed, to provide a range of speed and torque outputs necessary for vehicular travel.

[0004] Automatic Transmission Systems include a set of planetary gears controlled by friction elements such as clutches and brakes usually coupled to coupling devices subjected to slip such as hydraulic torque converters or fluid coupling devices with or without lock-up clutches. Automatic Transmission Systems have fixed input revolutions per minute (speed) to output speed ratio and are very expensive.

[0005] In conventional transmission systems such as, Automatic Transmission (AT) systems and Continuous Variable Transmission (CVT) systems, electro-hydraulic systems with electronic components such as sensors, couplers and microcontrollers are used to change gear ratio between an input gear and an output gear of the transmission system that sometimes leads to unreliable operation of the transmission system due to failure of the electronic components. Also, such transmission systems require a separate hydraulic pump resulting in high fuel consumption. Additionally, manufacturing cost associated with such conventional transmission systems are high as components used in such transmission systems are required to be precise and electronic components used in such transmission systems are expensive. [0006] There is therefore a need in the art to provide for transmission systems capable of infinitely varying speed ratio between the input shaft and the output shaft between minimum and maximum limits at all speed and torque requirements at driving wheels of an automobile. Further, there exists a need to provide for an efficient transmission system capable of providing automatic transmission with manual acceleration of the automobile.

[0007] As used in the description herein and throughout the claims that follow, the meaning of "a," "an," and "the" includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of "in" includes "in" and "on" unless the context clearly dictates otherwise.

[0008] In some embodiments, the numerical parameters set forth in the written description and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by a particular embodiment. In some embodiments, the numerical parameters should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of some embodiments of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as practicable. The numerical values presented in some embodiments of the invention may contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements.

[0009] The recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g. "such as") provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.

[0010] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified thus fulfilling the written description of all groups used in the appended claims.

OBJECTS OF THE INVENTION

[0011] It is an object of the present disclosure to provide a transmission system capable of infinitely varying speed and torque outputs between minimum and maximum limits necessary for vehicular travel.

[0012] It is another object of the present disclosure to provide a transmission system with improved reliability.

[0013] It is another object of the present disclosure to provide a transmission system that improves fuel efficiency of an automobile.

[0014] It is another object of the present disclosure to provide a transmission system that provides automatic transmission with manual acceleration of the automobile.

[0015] It is yet another object of the present disclosure to provide a transmission system that is cost efficient.

[0016] It is still another object of the present disclosure to provide a transmission system that is free of any slippage during transmission of mechanical power.

SUMMARY

[0017] The present disclosure pertains to transmission systems capable of infinitely varying speed and torque at driving wheels of an automobile. Aspects of the present disclosure provide a transmission system that includes a Positively Infinitely Variable (PIV) drive unit to infinitely vary speed of at least a pair of driving wheels of an automobile, and a servo mechanism including a differential unit and at least one hydraulic accumulator configured to modulate gear ratio of the PIV drive unit until torque on a first bevel pinion gear of the differential unit is slightly less than torque on a second bevel pinion gear of the differential unit, wherein the servo mechanism senses speed and torque differences between the first bevel pinion gear and the second bevel pinion gear and corrects gear ratio of the PIV drive unit.

[0018] In an embodiment, the PIV drive includes an input shaft and an output shaft, the input shaft operatively coupled with the first bevel pinion gear of the differential unit and the output shaft operatively coupled to a gearbox of the automobile to allow transfer of rotary motion from the differential unit to the gearbox. [0019] In an embodiment, the servo mechanism enables rotation of a control screw of the PIV unit that modulates the gear ratio of the PIV drive by effectively engaging at least two splined conical discs mounted on the input shaft of the PIV drive.

[0020] In an embodiment, the second bevel pinion gear is operatively coupled with a piston rod of a hydraulic cylinder such that displacement of the piston rod results in rotation of the second bevel pinion gear. In an embodiment, displacement of the piston rod of the hydraulic cylinder is actuated by the at least one hydraulic accumulator.

[0021] In an embodiment, the second bevel pinion gear is operatively connected to a rack such that displacement of the piston rod of the hydraulic cylinder enables displacement of the rack.

[0022] In an embodiment, back pressure of the hydraulic cylinder is infinitely varied by a taper wedge and a relief valve connected to the piston rod of the hydraulic cylinder such that displacement of the piston rod within the hydraulic cylinder results in displacement of the tae.

[0023] In an embodiment, displacement of the rack is governed by a lever mechanism comprising a rotary valve, a lever and a cylinder operable to enable displacement of the piston rod of the hydraulic cylinder.

[0024] In an embodiment, the hydraulic cylinder is coupled with a high pressure hydraulic accumulator and a low pressure hydraulic accumulator depending on positioning of a lever and engagement of at least a clutch of the automobile.

[0025] In an embodiment, after achieving a desired acceleration of the automobile, the lever is shifted to a pre-defined position after engaging the clutch to activate the hydraulic cylinder and displace a fluid into the low pressure hydraulic accumulator and connect the high pressure hydraulic accumulator to the hydraulic cylinder thereby constantly maintaining torque of the engine.

[0026] In an embodiment, in case when torque on the second bevel pinion gear is less than pulling torque of the hydraulic cylinder, the hydraulic cylinder pulls the rack. In an embodiment, displacement of the rack results in rotation of a third bevel pinion gear that rotates a control screw of the PIV drive unit thereby modulating gear ratio between the input shaft and the output shaft of the PIV drive unit until torque on the first bevel pinion gear is slightly less than torque on the second bevel pinion gear.

[0027] In an embodiment, in case when torque on the first bevel pinion gear is greater than torque applied by the hydraulic cylinder on the second bevel pinion gear through the rack, the second bevel pinion gear starts rotation against force applied by the piston rod of the hydraulic cylinder thereby displacing the rack. In an embodiment, displacement of the rack results in rotation of a third bevel pinion gear that rotates a control screw of the PIV drive unit thereby modulating gear ratio between the input shaft and the output shaft of the PIV drive unit until torque on the first bevel pinion gear is slightly less than torque on the second bevel pinion gear.

[0028] Those skilled in the art will further appreciate the advantages and superior features of the disclosure together with other important aspects thereof on reading the detailed description that follows in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings are included to provide a further understanding of the present disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[0030] In the figures, similar components and/or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label with a second label that distinguishes among the similar components. If only the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label.

[0031] FIG. 1 illustrates an exemplary schematic representation of a transmission system for infinitely varying speed and torque outputs between minimum and maximum limits at wheels of an automobile in accordance with an embodiment of the present disclosure.

[0032] FIG. 2 illustrates an exemplary schematic representation of the transmission system incorporating a lever mechanism to effect displacement of a rack in accordance with an embodiment of the present disclosure.

[0033] FIG. 3 illustrates an exemplary schematic representation of the transmission system incorporating two hydraulic accumulators in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION [0034] If the specification states a component or feature "may", "can", "could", or

"might" be included or have a characteristic, that particular component or feature is not required to be included or have the characteristic.

[0035] Exemplary embodiments will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments are shown. This disclosure may however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. These embodiments are provided so that this disclosure will be thorough and complete and will fully convey the scope of the disclosure to those of ordinary skill in the art. Moreover, all statements herein reciting embodiments of the disclosure, as well as specific examples thereof, are intended to encompass both structural and functional equivalents thereof. Additionally, it is intended that such equivalents include both currently known equivalents as well as equivalents developed in the future (i.e., any elements developed that perform the same function, regardless of structure).

[0036] Various terms as used herein are shown below. To the extent a term used in a claim is not defined below, it should be given the broadest definition persons in the pertinent art have given that term as reflected in printed publications and issued patents at the time of filing.

[0037] The present invention relates to transmission systems capable of infinitely varying speed and torque at driving wheels of an automobile. Aspects of the present disclosure provide a transmission system that includes a Positively Infinitely Variable (PIV) drive unit to infinitely vary speed of at least a pair of driving wheels of an automobile, and a servo mechanism including a differential unit and at least one hydraulic accumulator configured to modulate gear ratio of the PIV drive unit until torque on a first bevel pinion gear of the differential unit is slightly less than torque on a second bevel pinion gear of the differential unit, wherein the servo mechanism senses speed and torque differences between the first bevel pinion gear and the second bevel pinion gear and corrects gear ratio of the PIV drive unit.

[0038] FIG. 1 illustrates an exemplary representation of a transmission system for infinitely varying speed and torque outputs between minimum and maximum limits at driving wheels of an automobile in accordance with an embodiment of the present disclosure. In an aspect, the transmission system (also referred to as "transmission" or "servo transmission system" hereinafter) can include a servo mechanism including at least one hydraulic accumulator 102 (also referred to as "accumulator" hereinafter) and a differential unit 104 that includes a set of gears arranged to allow at least a pair of drive wheels to turn at different rotational speeds (also referred to as "revolution per minute" or "speed" or "RPM") while receiving power from an engine of the automobile.

[0039] In an aspect, the transmission system can include a Positively Infinitely

Variable (PIV) drive unit 108 to allow transmission of infinitely variable torque from the differential unit 104 to a clutch 110 of the automobile without any slip. In an aspect, the PIV drive unit 108 can include an input shaft 112 and an output shaft 114. Splined conical discs 116-1, 116-2, 116-3 and 116-4 (collectively referred to as 116) are mounted on each of the input shaft 112 and the output shaft 114. A chain drive 118 is configured over interface of the splined conical discs 116 such that rotation of the input shaft 112 and the output shaft 114 when the splined conical discs 116 at both the input shaft 112 and the output shaft 114 are engaged can enable transmission of rotary motion from the input shaft 112 to the output shaft 114 at a specific gear ratio between them. A control screw 126 can be configured with arms 120 of the PIV drive unit to enable effective engagement of the splined conical discs 116 mounted on the input shaft 112 and the output shaft 114 of the PIV drive 108, where tightening of the control screw 126 can enable engagement of the splined conical discs 116 mounted on any of the input shaft 112 and the output shaft 114, and slackening of the control screw 126 can enable disengagement of the splined conical discs 116 mounted on any of the input shaft 112 and the output shaft 114.

[0040] In an aspect, the input shaft 112 of the PIV drive unit 108 can be coupled to a first bevel pinion gear 122 of the differential unit 104, for instance, the input shaft 112 of the PIV drive unit 108 can be coupled to the first bevel pinion gear 122 of the differential unit 104 via a gearing mechanism, and the output shaft 114 of the PIV drive unit 108 can be operatively coupled to a reverse, forward and neutral mechanism gearbox 124 of the automobile, for instance, the output shaft 114 of the PIV drive unit 108 can be operatively coupled to the gearbox 124 via a gearing mechanism, to allow transfer of rotary motion from the differential unit 104 to the gearbox 124.

[0041] It would be appreciated that the proposed servo transmission system is free of any slippage during transmission of mechanical power from the engine to the driving wheels. By using the PIV drive unit 108 in the servo transmission mechanism, any slippage in the transmission of the mechanical power can be prevented and hence, reliability of the servo transmission system can be improved.

[0042] In an aspect, a hydraulic accumulator 102 is an energy storage device in which a non-compressible fluid is held under pressure applied by an external source. The external source can be a compressed gas, a spring, a raised weight and the like. The hydraulic accumulator 124 can enable a hydraulic system to cope with extremes of demand using a less powerful pump, to respond more quickly to a temporary demand, and to smooth out pulsations. The accumulator 124 can include a cylinder with two chambers separated by a piston, an elastic diaphragm, a totally enclosed bladder and the like. One chamber contains a fluid and is connected to a fluid reservoir to receive the fluid. The second chamber contains either the fluid or any other fluid such as a liquid or a gas under pressure that provides compressive force on the fluid contained in the first chamber. As volume of the fluid in the second chamber changes, the pressure of the fluid in both the first and the second chamber changes inversely.

[0043] In an aspect, an output shaft 102 of the engine can be connected to a drive pinion gear 128 of the differential unit 104. The first bevel pinion gear 122 of the differential unit can be operatively connected to an input pinion gear 128 of the PIV drive unit 108, where the PIV drive unit 108 can infinitely vary speed ratio between the input shaft 112 and the output shaft 114 between minimum and maximum limits by rotating the control screw 126 with the help of a second bevel pinion gear 130, a rack 132 and a third bevel pinion gear 134. The second bevel pinion gear 130 of the differential unit 104 can be operatively connected to the rack 132 such that rotation of the second bevel pinion gear 130 causes displacement of the rack 132.

[0044] In an aspect, the servo mechanism can include a hydraulic cylinder 136 configured to pull the rack 132 with a continuous counter balancing force acting on the rack 132 using the at least one gas filled hydraulic accumulator 102. The counter balancing force acting on the second bevel pinion gear 130 through the rack 132 by the hydraulic cylinder 136 can be equal to ratio of the speed of the drive pinion gear 128 to speed of the first bevel pinion gear 122 multiplied by peak torque of the engine minus back pressure on opposite side of the accumulator 102 of the hydraulic cylinder 136. The back pressure on the opposite side of the accumulator 102 of the hydraulic cylinder 136 can be controlled by a relief valve 138.

[0045] In an aspect, back pressure in the hydraulic cylinder 136 depends on gear ratio of the PIV drive unit 108. For instance, when gear ratio between the input shaft 112 and the output shaft 114 of the PIV drive unit 108 is maximum, the back pressure can also be maximum and when the gear ratio between the input shaft 112 and the output shaft 114 of the PIV drive unit 108 is minimum, the back pressure can also be minimum. In an aspect, maximum back pressure of the hydraulic cylinder 136 depends on torque at which the engine can accelerate. Higher the back pressure, higher the acceleration. [0046] In an aspect, one end of a piston rod capable of reciprocating within the hydraulic cylinder 136 can be operatively connected to the rack 132 and other end is connected to a taper wedge 140. The back pressure in the hydraulic cylinder 136 can be infinitely varied by the taper wedge 140 and the relief valve 138. Displacement of the piston rod of the hydraulic cylinder 136 can cause displacement of the taper wedge 140 which can vary pressure of the relief valve 138 by action of a plunger 146. A spring can also be used for back pressure in place of the taper wedge 140 and the relief valve 138.

[0047] In an embodiment, when gear is at neutral position of the gearbox 124, the first bevel pinion gear 122 of the differential unit 104 can rotate freely at low torque as the PIV drive unit 108 is not connected to wheels and the second bevel pinion gear 130 is held in position by the hydraulic cylinder 136 at minimum gear ratio between the input shaft 112 and the output shaft 114 of the PIV drive unit 108. Holding torque developed by the hydraulic cylinder 136 on the second bevel pinion gear 130 equals to ratio of speed of the drive pinion gear 128 to speed of the first bevel pinion gear 122 multiplied by engine peak torque minus back pressure controlled by the relief valve 138.

[0048] In an embodiment, if torque on the first bevel pinion gear 122 is greater than torque applied by the hydraulic cylinder 136 on the second bevel pinion gear 130 through the rack 132 due to any or a combination of load on wheels and due to engine acceleration, the second bevel pinion gear 130 can start rotation against force applied by the piston rod of the hydraulic cylinder 136 thereby displacing the rack 132. Displacement of the rack 132 can cause rotation of the third bevel pinion gear 134 that in turn rotates the control screw 126 of the PIV drive unit 108 thereby increasing gear ratio between the input shaft 112 and the output shaft 114 of the PIV drive unit 108 until torque on the first bevel pinion gear 122 is slightly less than torque on the second bevel pinion gear 130 which holds the piston rod of the hydraulic cylinder 136 in position.

[0049] In an embodiment, if torque on the second bevel pinion gear 130 is less than pulling torque of the hydraulic cylinder 136, the hydraulic cylinder 136 can pull the rack 132 thereby reducing speed gear ratio between the input shaft 112 and the output shaft 114 of the PIV drive unit 108 until torque on the first bevel pinion gear 122 is slightly less than torque on the second bevel pinion gear 130 which holds the piston rod of the hydraulic cylinder 136 in position.

[0050] In an aspect, the servo mechanism can continuously sense torque differences between the first bevel pinion gear 122 and the second bevel pinion gear 130 of the differential unit 104 and can correct the gear ratio of the PIV drive unit 108 infinitely between minimum and maximum limits at all speeds and torque requirement at the driving wheels of the automobile.

[0051] In an embodiment, when a clutch pedal of the automobile is pressed before a clutch 110 is disengaged or when the clutch 110 is configured as a half clutch, hydraulic oil can flow into the hydraulic cylinder 136 through a first pipe 142 that can actuate the hydraulic cylinder 136 and can further actuate a valve 148 (also referred to as "actuating valve" hereinafter) blocking the flow of oil from the oil tank to the relief valve 138 so that the gear ratio between the input shaft 112 and the output shaft 114 of the PIV drive unit 108 is maximum. The first pipe 142 can always be connected to an oil tank when clutch pedal is not pressed. Hydraulic oil can flow through a check valve 144 from the oil tank to avoid generation of vacuum during displacement of the hydraulic cylinder 136. In an embodiment, flow of the hydraulic oil from the oil tank to the hydraulic cylinder 136 can be regulated by using a shut-off valve 150 that can stop the flow of the oil when any anomaly in the transmission system is detected, for instance, when a false positive operation of the check valve 144 is triggered.

[0052] In an embodiment, when the clutch pedal is pressed, the clutch 110 can disengage and forward gear can be engaged. With engagement of the forward gear, high pressure oil flows into the hydraulic cylinder 136 through the first pipe 142 activating the hydraulic cylinder 136 and the actuating valve 148 to block flow of oil to the relief valve 138. The hydraulic cylinder 136 displaces the rack 132 so that speed ratio between the input shaft 112 and the output shaft 114 of the PIV drive unit 108 can be at a maximum limit.

[0053] In an aspect, a gear mounted on the output shaft 114 of the PIV drive unit 108 can be connected to the forward, reverse and neutral mechanism gearbox 124 of the automobile through the clutch 110 and a freewheel/overrunning clutch 106. The servo mechanism can adjust the gear ratio of the PIV drive unit 108 to match with vehicle speed to transmit maximum possible energy by the overrunning clutch 106 to avoid dragging of the engine by the automobile.

[0054] It would be appreciated that the servo mechanism can be configured with more than one hydraulic accumulators to improve operational performance of the transmission system, and any such configuration/arrangement is well within the scope of the present disclosure.

[0055] FIG. 2 illustrates an exemplary schematic representation of the transmission system incorporating a lever mechanism to effect displacement of a rack in accordance with an embodiment of the present disclosure. In an aspect, in place of the taper wedge 140, the relief valve 138 and the valve 148 as illustrated and described in FIG. 1, a lever mechanism 200 can be used to actuate and/or regulate displacement of the piston rod of the hydraulic cylinder 136 thereby regulating displacement of the rack 132.

[0056] In an aspect, the lever mechanism 200 can include a cylinder 206 connected to the hydraulic cylinder 136 through a pipe 214 and connected to a rotary valve 210 through a pipe 216. The rotary valve 210 can control pumping action of the hydraulic accumulator 102 and can further regulate displacement of the piston rod of the hydraulic cylinder 136.

[0057] In an aspect, the rotary valve 210 can include a lever 212 that can be positioned along three positions of the rotary valve 210, namely, positions A, B and C. By positioning lever 212 at position A, hydraulic pressure line 206 is connected to the cylinder 202 through a pipe 218 and the cylinder 202 is connected to the hydraulic cylinder through the pipe 214 thereby activating the cylinder 202 to effect displacement of the rack 132 so that the gear ration of the input shaft 112 and the output shaft 114 of the PIV drive unit 108 can be at a maximum limit.

[0058] In an embodiment, when clutch pedal is pressed before the clutch 110 is disengaged and in condition when a half clutch is used, the clutch pedal shifts the lever 212 to position A and after releasing the clutch pedal lever 212 is shifted to position B of the rotary valve 210. By positioning the lever 212 at position B, pipe 214 is connected to a tank 204 and hydraulic oil from the cylinder 202 flows freely into the tank 204 during upward movement of the piston of the cylinder 202.

[0059] In an embodiment, when the lever is positioned at position C, pressure line

206 connected to the hydraulic cylinder 136 through the pipe 216 thereby activating the hydraulic cylinder 136 and displacing oil into the cylinder 202 through the pipe 214 and displacing the rack 132 so that gear ratio of the PIV drive unit 108 increases from instantaneous gear ratio to assist in acceleration of the automobile. In an embodiment, increase in gear ratio of the PIV drive unit 108 amounts to displacement of piston of the cylinder 202 which further amounts to displacement of oil by the hydraulic cylinder 136.

[0060] In an embodiment, the lever 212 is shifted to position C when high acceleration of the automobile is required, for instance, during overtaking and climbing slopes. After reaching the desired or maximum acceleration, the lever 212 is shifted to position B. In an embodiment, when lever 212 is positioned at position C and when the rack 132 pulls piston rod of the hydraulic cylinder 136 by rotating the second bevel pinion gear 130, hydraulic oil flows into the cylinder 202 through a check valve 208 to avoid generation of vacuum inside the cylinder 202. In an aspect, power is transferred from the outer shaft of the PIV drive unit 108 to axle of the driving wheels through a clutch 110, a freewheel 106 and a forward, reverse and neutral mechanism gearbox 124. In an embodiment, during idling of the engine of the automobile while the automobile is in motion, the servo mechanism can adjust/modulate gear ratio of the PIV drive unit 108 to match with speed of the automobile to transmit maximum possible energy using the freewheel 106 to avoid dragging of the engine by the automobile.

[0061] In an aspect, displacement of the rack 132 causes rotation of the third bevel pinion gear 134 that actuates rotation of the control screw 126 of PIV drive unit 108, thereby increasing gear ratio between the input shaft 112 and the output shaft 114 until torque on the first bevel pinion gear 122 is slightly less than torque on the second bevel pinion gear 130 such that torque on the engine is always maintained constant at all speeds and torque requirement at the driving wheels.

[0062] In an embodiment, the counter balancing force acting on second bevel pinion gear 130 through the rack 132 by the hydraulic cylinder 136 can be equal to ratio of speed of the drive pinion gear 128 to speed of the first bevel pinion gear 122 multiplied by a specific percentage of peak torque of the engine.

[0063] FIG. 3 illustrates an exemplary representation of the transmission system for infinitely varying speed and torque outputs between minimum and maximum limits at wheels of the automobile incorporating two hydraulic accumulators in accordance with an embodiment of the present disclosure. In an aspect, the servo transmission system can include two hydraulic accumulators 302 and 304 that can assist in movement of the rack 132 connected with piston rod of the hydraulic cylinder 136, where the hydraulic cylinder 136 pulls the rack 132 with continuous counter balancing force acting on the rack 132 using the hydraulic accumulators 302 and 304 depending on position of a lever 312 of a rotary valve 310 controlling pumping action of the hydraulic accumulators 302 and 304.

[0064] In an aspect, the rotary valve 310 can consist of two positions, namely, positions A and B. In an aspect, before shifting the lever 312 between positions A and B, clutch pedal is to be pressed such that hydraulic oil flows through a first pipe 306 actuating the hydraulic cylinder 136 so that oil from the hydraulic cylinder 136 flows back into the any of the hydraulic accumulators that is connected to the hydraulic cylinder 136 through a second pipe 308.

[0065] In an embodiment, when high acceleration is required for the automobile during overtaking or climbing steep slopes, the clutch pedal is to be pressed and the lever 312 is to be shifted to position A. After reaching desired or maximum acceleration, the lever 312 can be shifted to position B. By positioning the Lever at position A, low pressure hydraulic accumulator 304 can be connected to the hydraulic cylinder 136 through a second pipe 308. On the contrary, when the lever 312 is positioned at position B, high pressure hydraulic accumulator 302 can be connected to the hydraulic cylinder 136 through the second pipe 308.

[0066] In an embodiment, when the lever 312 of the rotary valve 310 is at position A, the low pressure Hydraulic Accumulator 304 can be connected to the hydraulic cylinder 136. The counter balancing force acting on second bevel pinion gear 130 through the rack 132 by the hydraulic cylinder 136 can be equal to ratio of speed of the drive pinion gear 128 to speed of the first bevel pinion gear 122 multiplied by a specific percentage of peak torque of the engine so that the engine has maximum acceleration. The specific percentage of the peak torque can be defined by 50% to 80% of total peak torque of the engine. However, the specific percentage of the peak torque of the engine can be varied based on performance of the engine, and any such configuration/arrangement is well within the scope of the present disclosure.

[0067] In an embodiment, when the lever 312 of rotary valve 310 connected to the high pressure accumulator 302 is at position B, the counter balancing force acting on the second bevel pinion gear 130 through the rack 132 by the hydraulic cylinder 136 can be equal to ratio of speed of the drive pinion gear 128 to speed of the first bevel pinion gear 122 multiplied by a specific percentage of peak torque of the engine. The specific percentage of the peak torque of the engine can be defined by reduction of a small percentage of the peak torque from the total peak torque of the engine.

[0068] In an aspect, displacement of the rack 132 can cause rotation of the third bevel pinion gear 134 that in turn rotates the control screw 126 of the PIV drive unit 108 thereby increasing gear ratio between the input shaft 112 and the output shaft 114 of the PIV drive unit 108 until torque on the first bevel pinion gear 122 is slightly less than torque on the second bevel pinion gear 130 such that torque on the engine is always constant at all speeds and torque requirements at the driving wheels.

[0069] In an embodiment, if torque on the second bevel pinion gear 130 is less than pulling torque of the hydraulic cylinder 136, the hydraulic cylinder 136 can pull the rack 132 thereby reducing speed gear ratio between the input shaft 112 and the output shaft 114 of the PIV drive unit 108 until torque on the first bevel pinion gear 122 is slightly less than torque on the second bevel pinion gear 130 such that torque on the engine is always constant at all speeds and torque requirements at the driving wheels. [0070] In an embodiment, when gear is at neutral position of the gearbox 124 and when the lever 312 is at position B, the first bevel pinion gear 122 of the differential unit 104 can rotate freely at low torque as the PIV drive unit 108 is not connected to wheels and the second bevel pinion gear 130 is held in position by the hydraulic cylinder 136 at minimum gear ratio between the input shaft 112 and the output shaft 114 of the PIV drive unit 108. Holding torque developed by the hydraulic cylinder 136 on the second bevel pinion gear 130 equals to ratio of the drive pinion gear speed to the first bevel pinion gear 122 speed multiplied by the specific percentage of engine peak torque.

[0071] In an embodiment, when the clutch pedal is pressed, the clutch 110 disengages and forward gear is engaged and hydraulic oil flows into the hydraulic cylinder 136 through the first pipe 306 thereby activating the hydraulic cylinder 136 to displace oil into the high pressure hydraulic accumulator 302 effecting displacement of the rack 132 so that speed ratio between the input shaft 112 and the output shaft 114 gear ratio of the PIV unit can be at a maximum limit. At the same time, the lever 312 of the rotary valve 310 can be shifted to position A to enable connection of the low pressure Hydraulic accumulator 304 to the hydraulic cylinder 136. Holding torque on second bevel pinion gear 130 can be equal to ratio of speed of the drive pinion gear 128 to speed of the first bevel pinion gear 122 multiplied by 50% to 80% of engine peak torque. The engine torque is maintained at 50% to 80% of the peak torque by the servo mechanism depending on charging pressure of the low pressure hydraulic accumulator 304 so that the engine can accelerate.

[0072] In an aspect, the servo mechanism can continuously sense torque at first bevel pinion gear 122. If torque on first bevel pinion gear 122 is greater than torque applied by the hydraulic cylinder 136 on the second bevel pinion gear 130 through the rack 132 due to any or a combination of load on the driving wheels and engine acceleration, the second bevel pinion gear 130 starts rotating against force of the hydraulic cylinder 136 thereby displacing the rack 132.

[0073] In an aspect, displacement of the rack 132 causes rotation of the third bevel pinion gear 134 that actuates rotation of the control screw 126 of PIV drive unit 108, thereby increasing gear ratio between the input shaft 112 and the output shaft 114 until torque on the first bevel pinion gear 122 is slightly less than torque on the second bevel pinion gear 130 which holds the hydraulic cylinder 136 in position so that torque on the engine is always maintained constant at all speeds and torque requirement at the driving wheels.

[0074] In an aspect, a gear mounted on the output shaft 114 of the PIV drive unit 108 can be connected to the forward, reverse and neutral mechanism gearbox 124 of the automobile through the clutch 110 and a freewheel/overrunning clutch 106. The servo mechanism can adjust the gear ratio of the PIV drive unit 108 to match with vehicle speed to transmit maximum possible energy by the overrunning clutch 106 to avoid dragging of the engine by the automobile.

[0075] In an embodiment, if torque on the second bevel pinion gear 130 is less than pulling torque of the hydraulic cylinder 136, the hydraulic cylinder 136 can pull the rack 132 thereby reducing speed ratio between the input shaft 112 and the output shaft 114 of the PIV drive unit 108 until torque on the first bevel pinion gear 122 is slightly less than torque on the second bevel pinion gear 130 which holds the piston rod of the hydraulic cylinder 136 in position and maintains constant torque on engine at all speeds and torque requirement at the driving wheels.

[0076] In an embodiment, after reaching desired acceleration, the lever 312 can be shifted to position B after pressing the clutch pedal to activate the hydraulic cylinder 136 and displace oil into the low pressure hydraulic accumulator 304 and connect the high pressure hydraulic accumulator 302 to the hydraulic cylinder 136. Thus, engine torque is constantly maintained by the servo mechanism.

[0077] It would be appreciated that although embodiments of the present disclosure are explained in terms of a transmission system for an automobile, scope of the present disclosure is not limited to the same in any way whatsoever, and any other form of application of the transmission system in a machinery and an automobile is well within the scope of the present disclosure.

[0078] Thus the present disclosure provides transmission system that includes a

Positively Infinitely Variable (PIV) drive unit 108 to infinitely vary speed of at least a pair of driving wheels of an automobile, and a servo mechanism including a differential unit 104 and at least one hydraulic accumulator 102 configured to modulate gear ratio of the PIV drive unit 108 until torque on a first bevel pinion gear 122 of the differential unit 104 is slightly less than torque on a second bevel pinion gear 130 of the differential unit 104, wherein the servo mechanism senses speed and torque differences between the first bevel pinion gear 122 and the second bevel pinion gear 130 and corrects gear ratio of the PIV drive unit 108. The disclosed transmission system is capable of providing automatic transmission with manual acceleration.

[0079] It should be apparent to those skilled in the art that many more modifications besides those already described are possible without departing from the inventive concepts herein. The inventive subject matter, therefore, is not to be restricted except in the spirit of the appended claims. Moreover, in interpreting both the specification and the claims, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms "includes" and "including" should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced. Where the specification claims refers to at least one of something selected from the group consisting of A, B, C ....and N, the text should be interpreted as requiring only one element from the group, not A plus N, or B plus N, etc. The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the appended claims.

[0080] While embodiments of the present disclosure have been illustrated and described, it will be clear that the disclosure is not limited to these embodiments only. Numerous modifications, changes, variations, substitutions, and equivalents will be apparent to those skilled in the art, without departing from the spirit and scope of the disclosure, as described in the claims.

ADVANTAGES OF THE INVENTION

[0081] The present disclosure provides a transmission system capable of infinitely varying speed and torque outputs between minimum and maximum limits necessary for vehicular travel.

[0082] The present disclosure provides a transmission system with improved reliability.

[0083] The present disclosure provides a transmission system that improves fuel efficiency of an automobile.

[0084] The present disclosure provides a transmission system that provides automatic transmission with manual acceleration of the automobile. [0085] The present disclosure provides a transmission system that is cost efficient.

[0086] The present disclosure provides a transmission system that is free of any slippage during transmission of mechanical power.

Claims

I Claim:

1. A transmission system comprising: a Positively Infinitely Variable (PIV) drive unit to infinitely vary speed of at least a pair of driving wheels of an automobile; and a servo mechanism comprising a differential unit and at least one hydraulic accumulator configured to modulate gear ratio of the PIV drive unit until torque on a first bevel pinion gear of the differential unit is slightly less than torque on a second bevel pinion gear of the differential unit, wherein the servo mechanism senses speed and torque differences between the first bevel pinion gear and the second bevel pinion gear and corrects gear ratio of the PIV drive unit.

2. The transmission system of claim 1, wherein the PIV drive comprises an input shaft and an output shaft, the input shaft operatively coupled with the first bevel pinion gear of the differential unit and the output shaft operatively coupled to a gearbox of the automobile to allow transfer of rotary motion from the differential unit to the gearbox.

3. The transmission system of claim 1, wherein the servo mechanism enables rotation of a control screw of the PIV unit that modulates the gear ratio of the PIV drive by effectively engaging at least two splined conical discs mounted on the input shaft of the PIV drive.

4. The transmission system of claim 1, wherein the second bevel pinion gear is operatively coupled with a piston rod of a hydraulic cylinder such that displacement of the piston rod results in rotation of the second bevel pinion gear, and wherein displacement of the piston rod of the hydraulic cylinder is actuated by the at least one hydraulic accumulator.

5. The transmission system of claim 4, wherein the second bevel pinion gear is operatively connected to a rack such that displacement of the piston rod of the hydraulic cylinder enables displacement of the rack.

6. The transmission system of claim 5, wherein back pressure of the hydraulic cylinder is infinitely varied by a taper wedge and a relief valve connected to the piston rod of the hydraulic cylinder such that displacement of the piston rod within the hydraulic cylinder results in displacement of the taper wedge and a variation in pressure of the relief valve.

7. The transmission system of claim 5, wherein displacement of the rack is governed by a lever mechanism comprising a rotary valve, a lever and a cylinder operable to enable displacement of the piston rod of the hydraulic cylinder.

8. The transmission system of claim 4, wherein the hydraulic cylinder is coupled with a high pressure hydraulic accumulator and a low pressure hydraulic accumulator depending on positioning of a lever and engagement of at least a clutch of the automobile.

9. The transmission system of claim 8, wherein after achieving a desired acceleration of the automobile, the lever is shifted to a pre-defined position after engaging the clutch to activate the hydraulic cylinder and displace a fluid into the low pressure hydraulic accumulator and connect the high pressure hydraulic accumulator to the hydraulic cylinder thereby constantly maintaining torque of the engine.

10. The transmission system of claim 1, wherein in case when torque on the second bevel pinion gear is less than pulling torque of the hydraulic cylinder, the hydraulic cylinder pulls the rack, and wherein displacement of the rack results in rotation of a third bevel pinion gear that rotates a control screw of the PIV drive unit thereby modulating gear ratio between the input shaft and the output shaft of the PIV drive unit until torque on the first bevel pinion gear is slightly less than torque on the second bevel pinion gear.

11. The transmission system of claim 1, wherein in case when torque on the first bevel pinion gear is greater than torque applied by the hydraulic cylinder on the second bevel pinion gear through the rack, the second bevel pinion gear starts rotation against force applied by the piston rod of the hydraulic cylinder thereby displacing the rack, and wherein displacement of the rack results in rotation of a third bevel pinion gear that rotates a control screw of the PIV drive unit thereby modulating gear ratio between the input shaft and the output shaft of the PIV drive unit until torque on the first bevel pinion gear is slightly less than torque on the second bevel pinion gear.