Claims:We claim,
1) A transmission control system to prevent engine stall, comprises of,

a) an engine (101);
b) a clutch unit (102) adjacent to the engine (101), wherein the clutch unit (102) comprises of a forward clutch pack and a reverse clutch pack;
c) a transmission system (103), said transmission system (103) is operatively coupled with the clutch unit (102);
d) a fluid system (104), said fluid system (104) is in communication with the transmission system (103) for cooling and/or lubrication purpose;
e) a fluid valve block (105), said fluid valve block (105) is in contact with the fluid system (104) fluidically, wherein the fluid valve block (105) comprises of a forward valve and a reverse valve, said forward valve supplies or drain pressurised fluid to or from the forward clutch pack and said reverse valve supplies or drain pressurised fluid to or from the reverse clutch pack; and
f) an electronic control unit (106), said electronic control unit (106) sends a pressure control signal to the fluid valve block (105), said pressure control signals are determined by means of input from a plurality of sensors and/or a stored data.

2) A transmission control system to prevent engine stall as claimed in claim 1, said forward clutch pack and reverse clutch pack is a wet clutch pack.

3) A transmission control system to prevent engine stall as claimed in claim 1, wherein the transmission system (103) is a mechanical transmission system.

4) A transmission control system to prevent engine stall as claimed in claim 1, wherein the fluid system (104) is hydraulic fluid system and said fluid is hydraulic.

5) A transmission control system to prevent engine stall as claimed in claim 1, wherein the forward valve and the reverse valve is a pressure proportional control valve.
6) A transmission control system to prevent engine stall as claimed in claim 1, said plurality of sensors are, a first sensor (107) and a second sensor (108).

7) A transmission control system to prevent engine stall as claimed in claim 1 and claim 6, said plurality of sensors are speed sensors.

8) A transmission control system to prevent engine stall as claimed in claim 1, claim 6 and claim 7, wherein the first sensor (107) measures speed of the engine (101) and the second sensor (108) measures speed of the transmission system (103), the measured speed values are transmitted to the electronic control unit (106).

9) A transmission control system to prevent engine stall as claimed in claim 1, said stored data are the data pertaining to the optimum performance of the vehicle, wherein the stored data is stored in the electronic control unit (106).

10) A method of controlling transmission system to prevent engine stall according to the selected gear ratio and the clutch pedal release, comprising of,

a) measuring the engine (101) speed by means of the first sensor (107), simultaneously measuring the transmission speed by means of the second sensor (108);
b) transmitting the measured speed values to the electronic control unit (106);
c) conveying a pressure control signal from the electronic control unit (106) to the fluid valve block (105); and
d) controlling the clutch unit (102), by means of pressure distribution by the fluid valve block (105) to the clutch unit (102), on the basis of the pressure control signal, to avoid engine stall.

11) A method of controlling transmission system to prevent engine stall according to the selected gear ratio and the clutch pedal release as claimed in claim 10, wherein the electronic control unit (106) process the pressure control signal by,

a) estimating clutch slip, operating gear ratio, engine torque and actual engine load as a function of clutch slip, for the measured speed values received by the electronic control unit (106);
b) comparing the estimated values and the measured speed values, with the stored data; and
c) processing the pressure control signal.

12) A method of controlling transmission system to prevent engine stall according to the selected gear ratio and the clutch pedal release as claimed in claim 10 and claim 11, wherein the pressure control signal is conveyed from the electronic control unit (106) to the forward valve in the fluid valve block (105), when the vehicle is operating in forward direction.

13) A method of controlling transmission system to prevent engine stall according to the selected gear ratio and the clutch pedal release as claimed in claim 10 and claim 11, wherein the pressure control signal is conveyed from the electronic control unit (106) to the reverse valve in the fluid valve block (105), when the vehicle is operating in forward direction.

14) A method of controlling transmission system to prevent engine stall according to the selected gear ratio and the clutch pedal release as claimed in claim 10, claim 11 and claim 12, wherein the forward clutch pack in the clutch unit (102) is controlled.

15) A method of controlling transmission system to prevent engine stall according to the selected gear ratio and the clutch pedal release as claimed in claim 10, claim 11 and claim 13, wherein the reverse clutch pack in the clutch unit (102) is controlled.

16) A method of controlling transmission system to prevent engine stall according to the selected gear ratio and the clutch pedal release as claimed in claim 10, claim 11, claim 12 and claim 14, wherein the forward clutch pack in the clutch unit (102) is partially engaged/disengaged.

17) A method of controlling transmission system to prevent engine stall according to the selected gear ratio and the clutch pedal release as claimed in claim 10, claim 11, claim 12 and claim 14, wherein the forward clutch pack in the clutch unit (102) is fully engaged/disengaged.

18) A method of controlling transmission system to prevent engine stall according to the selected gear ratio and the clutch pedal release as claimed in claim 10, claim 11, claim 13 and claim 15, wherein the reverse clutch pack in the clutch unit (102) is partially engaged/disengaged.

19) A method of controlling transmission system to prevent engine stall according to the selected gear ratio and the clutch pedal release as claimed in claim 10, claim 11, claim 13 and claim 15, wherein the reverse clutch pack in the clutch unit (102) is fully engaged/disengaged. , Description:A TRANSMISSION CONTROL SYSTEM TO PREVENT ENGINE STALL AND A METHOD THEREOF
FIELD OF THE INVENTION
The present invention relates to a transmission control system. In particular, the present invention relates to the transmission control system which uses only speed sensors to control transmission system for prevention of engine stall.
BACKGROUND OF THE INVENTION
Generally, to prevent engine stall of a tractor employed with a transmission system having wet clutch, the transmission control system requires various types of sensors, valves and pump controls to detect load conditions of engine. In order to prevent engine stall, load condition of the engine is continuously monitored. If the load condition is below the threshold, transmission condition is adjusted. This is achieved by means of various sensors, valves and control pump, thus the control system of the tractor is complex and expensive.
US Patent No. 6675577 discloses an engine control system for a compact utility tractor having an engine coupled to a hydrostatic transmission, that is coupled to a driven wheel, comprising: a controller; an engine speed sensor, signal-connected to said controller to send an actual engine speed signal to said controller; a speed control actuator having at least a forward and a neutral position, said speed control actuator causing speed command signals from said controller to adjust said hydrostatic transmission speed output to said wheel; said controller having circuitry that continuously monitors engine speed and the position of said control actuator; said controller having circuitry that records said engine speed at the occurrence of said neutral position of said speed control actuator as an unloaded engine speed; and when the engine speed signal decreases under load by a specified amount below said unloaded engine speed, said controller having circuitry that sends a control command to said hydrostatic transmission to reduce tractor speed proportional to the difference between said unloaded engine speed and said actual engine speed signal. In this invention, prevention of engine stall is achieved by utilising various sensors, valves and control pumps. Thus, making control system complex and also expensive.
US Patent No.9527511 discloses a control system for a work machine, the control system comprising: a power source; a hydrostatic transmission operatively coupled to the power source; and a controller configured to: determine whether a stall factor, relating to the hydrostatic transmission, is less than a first threshold value, determine whether a ground speed of the machine is less than a second threshold value, determine whether the work machine is experiencing a stall condition based on determining whether the stall factor is less than the first threshold value and determining whether the ground speed of the machine is less than the second threshold value, the work machine experiencing the stall condition when the stall factor is less than the first threshold value and the ground speed of the machine is less than the second threshold value, and actively and continuously control an engine speed of the work machine to reduce the engine speed below a threshold value and to provide an audible feedback to an operator of the work machine during the stall condition, the audible feedback indicating, to the operator, that the work machine is performing at capacity. In this invention, engine stall detection is based on ground speed of the machine but not on engine loading condition. Thus, making control system complex and also expensive.
For the above reason there is need in art to provide a control system which control the transmission system to prevent the engine stall condition and also the control system employing very less sensor and making the control system simple and cost effective.
OBJECTIVE OF THE INVENTION
The primary objective of the present invention is to provide a control system which controls the transmission system to prevent engine stall.
Another objective of the present invention is to provide a control system which utilises very few sensors to control the transmission system, in order to prevent engine stall.
Yet another objective of the present invention is to provide a control system which is cost effective by, eliminating various position sensors and hydraulic pumps and reducing the quantity of expensive control valves.
SUMMARY OF THE INVENTION
The present invention provides a transmission control system to prevent engine stall, comprising of: an engine (101); a clutch unit (102), wherein the clutch unit (102) comprises of a forward clutch pack and a reverse clutch pack; a transmission system (103), said transmission system (103) is operatively coupled with the said clutch unit (102); a fluid system (104), said fluid system (104) is in communication with the transmission system (103) for cooling and/or lubrication purpose, wherein the fluid system (104) is a hydraulic fluid system; a fluid valve block (105), said fluid valve block (105) is in contact with the fluid system (104) fluidically, wherein the fluid valve block (105) comprises of a forward valve and a reverse valve, said forward valve supplies or drain pressurised fluid to or from the forward clutch pack and said reverse valve supplies or drain pressurised fluid to or from the reverse clutch pack; and an electronic control unit (106), said electronic control unit (106) sends a pressure control signal to the fluid valve block (105), said pressure control signals are determined by means of input from a plurality of sensors and/or a stored data.
Said electronic unit control (106) is stored with plurality of data related to the vehicle performance including data related to the threshold engine speed for various loading condition and the operating speed ratio. a first sensor (107) and a second sensor (108) continuously monitor speed of the engine (101) and speed of the transmission system (103). The electronic control unit (106) continuously modulates the clutch in the clutch unit (102) by comparing the estimated values for the measured speed values with the stored data. Upon monitoring, if the measured speed values are dropping continuously and upon comparing the estimated values for the measured speed values with the stored data, the electronic control unit (106) conveys a pressure control signal to the fluid valve block (105). On the basis of conveyed signal, said fluid valve block (105) controls the clutch aggression and engage/disengage the clutch in the clutch unit (102), said engage/disengage is either partially or fully according to the selected gear ratio and clutch pedal release, to avoid the engine (101) stall.
BRIEF DESCRIPTION OF THE DIAGRAMS
Figure 1 shows the schematic block diagram of the transmission control system.
Figure 2 depicts the schematic layout of the transmission control system when the clutch unit is fully disengaged.
While the invention is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit the invention to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.
DETAILED DESCRIPTION OF THE INVENTION
The present invention as embodied by the "A transmission control system to prevent engine stall and a method thereof", succinctly fulfils the above-mentioned need(s) in the art. The present invention has objective(s) arising as a result of the above-mentioned need(s), said objective(s) being enumerated below. In as much as the objective(s) of the present invention are enumerated, it will be obvious to a person skilled in the art that, the enumerated objective(s) are not exhaustive of the present invention in its entirety, and are enclosed solely for the purpose of illustration. Further, the present invention encloses within its scope and purview, any structural alternative(s) and/or any functional equivalent(s) even though, such structural alternative(s) and/or any functional equivalent(s) are not mentioned explicitly herein or elsewhere, in the present disclosure. The present invention therefore encompasses also, any improvisation(s)/modification(s) applied to the structural alternative(s)/functional alternative(s) within its scope and purview. The present invention may be embodied in other specific form(s) without departing from the spirit or essential attributes thereof.
Throughout this specification, the use of the word "comprise" and variations such as "comprises" and "comprising" may imply the inclusion of an element or elements not specifically recited.
The present invention provides a transmission control system to prevent engine stall, comprises of, an engine (101); a clutch unit (102) adjacent to the engine (101), wherein the clutch unit (102) comprises of a forward clutch pack and a reverse clutch pack, said forward clutch pack and reverse clutch pack is a wet clutch pack; a transmission system (103), said transmission system (103) is operatively coupled with the clutch unit (102), wherein the transmission system (103) is a mechanical transmission system; a fluid system (104), said fluid system (104) is in communication with the transmission system (103) for cooling and/or lubrication purpose, wherein the fluid system (104) is hydraulic fluid system; a fluid valve block (105), said fluid valve block (105) is in contact with the fluid system (104) fluidically, wherein the fluid valve block (105) comprises of a forward valve and a reverse valve, wherein the forward valve and the reverse valve is a pressure proportional control valve, said forward valve supplies or drain pressurised fluid to or from the forward clutch pack and said reverse valve supplies or drain pressurised fluid to or from the reverse clutch pack; and an electronic control unit (106), said electronic control unit (106) sends a pressure control signal to the fluid valve block (105), said pressure control signals are determined by means of input from a plurality of sensors and/or a stored data.
Said plurality of sensors are, a first sensor (107) and a second sensor (108). Wherein said plurality of sensors are speed sensors. The first sensor (107) measures speed of the engine (101) and the second sensor (108) measures speed of the transmission system (103), the measured speed values are transmitted to the electronic control unit (106).
The electronic control unit (106) estimates the clutch slip, operating gear ratio, engine torque and actual engine load as a function of clutch slip, for the received measured speed values.
Said electronic control unit (106) having a plurality of processing and storing components including a processor and a memory unit. Said processor can be microprocessor. Said memory unit is stored with plurality of data related to the vehicle performance including data related to the threshold engine speed for various loading condition and the operating speed ratio. Said stored data is the data pertaining to the optimum performance of the vehicle. Wherein the stored data is stored in the electronic control unit (106).
The first sensor (107) and the second sensor (108) continuously monitor speed of the engine (101) and speed of the transmission system (103). The electronic control unit (106) continuously modulates the clutch in the clutch unit (102) by comparing the estimated values for the measured speed values with the stored data. Upon monitoring, if the measured speed values are dropping continuously and upon comparing the estimated values for the measured speed values with the stored data, the electronic control unit (106) conveys a pressure control signal to the fluid valve block (105). On the basis of conveyed signal, said fluid valve block (105) controls the clutch aggression and engage/disengage the clutch in the clutch unit (102), said engage/disengage is either partially or fully according to the selected gear ratio and clutch pedal release to avoid engine stall.
A method of controlling transmission system to prevent engine stall according to the selected gear ratio and clutch pedal release, comprising of,
• measuring the engine (101) speed by means of the first sensor (107), simultaneously measuring the transmission speed by means of the second sensor (108);
• transmitting the measured speed values to the electronic control unit (106);
• conveying a pressure control signal from the electronic control unit (106) to the fluid valve block (105); and
• controlling the clutch unit (102), by means of pressure distribution by the fluid valve block (105) to the clutch unit (102), on the basis of the pressure control signal, to avoid engine stall.
A method of controlling transmission system to prevent engine stall according to the selected gear ratio and clutch pedal release, wherein the electronic control unit (106) process the pressure control signal by,
• estimating clutch slip, operating gear ratio, engine torque and actual engine load as a function of clutch slip, for the measured speed values received by the electronic control unit (106);
• comparing the estimated values and the measured speed values, with the stored data; and
• processing the pressure control signal.
Upon comparing the estimated values for the measured speed values with the stored value, if the estimated values is greater than the stored value, the electronic control unit (106) convey the pressure signal to fluid valve block (105), to modulate the clutch aggression in the clutch unit (102) accordingly, to avoid engine stall.
If the estimated values for the measured speed values is lower than the stored value, the electronic control unit (106) convey the pressure signal to fluid valve block (105), to disengage the clutch in the clutch unit (102) from the engine (101), to avoid engine stall due to under load condition.
In an embodiment of the present invention, when a utility vehicle operating in forward direction, the clutch unit (102) is to be modulated according to the selected gear ratio and clutch pedal release. The first senor (107) and the second sensor (108) continuously measures speed of the engine (101) and the transmission system (103) respectively. The measured speed values are continuously transmitted to the electronic control unit (106).. Wherein the electronic control unit (106) estimates the clutch slip, the operating gear ratio and actual engine load as a function of clutch slip, for the measured speed values it received. Furthermore, the electronic control unit (106) compare the estimated values for the measured speed values with the stored value. If the estimated values for the measured speed values are greater than the stored value, the electronic control unit (106) conveys the pressure control signal to the forward valve in the fluid valve block (105), to modulate the forward clutch in the clutch unit (102) according to the selected gear ratio and clutch pedal release, to avoid the engine (101) stall.
In an another embodiment of the present invention, when a utility vehicle operating in reverse direction, the clutch unit (102) is to be modulated according to gear ratio selected and clutch pedal release. The first senor (107) and the second sensor (108) continuously measures speed of the engine (101) and the transmission system (103) respectively. The measured speed values are continuously transmitted to the electronic control unit (106). Wherein the electronic control unit (106) estimates the clutch slip, the operating gear ratio and actual engine load as a function of clutch slip, for the measured speed values it received. Furthermore, the electronic control unit (106) compares the estimated values for the measured speed values with the stored value. If the estimated values for the measured speed values are greater than the stored value, the electronic control unit (106) conveys the pressure control signal to the reverse valve in the fluid valve block (105), to modulate reverse clutch in the clutch unit (102) according to the selected gear ratio and clutch pedal release, to avoid the engine (101) stall.
In a still another embodiment of the present invention, when a utility vehicle operating in forward direction, the clutch unit (102) is to be modulated according to the selected gear ratio and clutch pedal release. The first senor (107) and the second sensor (108) continuously measures speed of the engine (101) and the transmission system (103) respectively. The measured speed values are continuously transmitted to the electronic control unit (106). Wherein the electronic control unit (106) estimates the clutch slip, the operating gear ratio and actual engine load as a function of clutch slip, for the measured speed values it received. Furthermore, the electronic control unit (106) compare the estimated values for the measured speed values with the stored value.. When the utility vehicle is pulled away at the higher speed ratio, the engine speed gradually reduces. at first instance of gradual reduction of the engine speed, the estimated values for the first instance measured speed values are greater than the stored value, the electronic control unit (106) conveys the pressure control signal to the forward valve in the fluid valve block (105) to modulate the forward clutch engagement accordingly. at second instance of gradual reduction of the engine speed, wherein the estimated values for the second instance measured speed values are greater than the stored value, but the measured speed values of the second instance is lower than the first instance, the electronic control unit (106) conveys the pressure control signal to the forward valve in the fluid valve block (105), to further modulate the forward clutch in the clutch unit (102) according to the selected gear ratio and clutch pedal release, to avoid the engine (101) stall.
In a yet another embodiment of the present invention, when a utility vehicle operating in reverse direction, the clutch unit (102) is to be modulated according to the selected gear ratio and clutch pedal release. The first senor (107) and the second sensor (108) continuously measures speed of the engine (101) and the transmission system (103) respectively. The measured speed values are continuously transmitted to the electronic control unit (106). Wherein the electronic control unit (106) estimates the clutch slip, the operating gear ratio and actual engine load as a function of clutch slip, for the measured speed values it received. Furthermore, the electronic control unit (106) compare the estimated values for the measured speed values with the stored value. When the utility vehicle is pulled away at the higher speed ratio, the engine speed gradually reduces. at first instance of gradual reduction of the engine speed, the estimated values for the first instance measured speed values are greater than the stored value, the electronic control unit (106) conveys the pressure control signal to the reverse valve in the fluid valve block (105) to modulate the reverse clutch engagement accordingly. At second instance of gradual reduction of the engine speed, wherein the estimated values for the second instance measured speed values are greater than the stored value, but the measured speed values of the second instance is lower than the first instance, the electronic control unit (106) conveys the pressure control signal to the reverse valve in the fluid valve block (105), to further modulate the reverse clutch in the clutch unit (102) according to the selected gear ratio and clutch pedal release, to avoid the engine (101) stall.
In a still another embodiment of the present invention, when a utility vehicle operating in forward direction, the clutch unit (102) is to be modulated according to the selected gear ratio and clutch pedal release. The first senor (107) and the second sensor (108) continuously measures speed of the engine (101) and the transmission system (103) respectively. The measured speed values are continuously transmitted to the electronic control unit (106). Wherein the electronic control unit (106) estimates the clutch slip, the operating gear ratio and actual engine load as a function of clutch slip, for the measured speed values it received. Furthermore, the electronic control unit (106) compare the estimated values for the measured speed values with the stored value. If the estimated values for the measured speed values are lower than the stored value, the electronic control unit (106) conveys the pressure control signal to the forward valve in the fluid valve block (105), to disengage the forward clutch in the clutch unit (102), either fully or partially according to the selected gear ratio and clutch pedal release, to avoid the engine stall.
In a yet another embodiment of the present invention, when a utility vehicle operating in reverse direction, the clutch unit (102) is to be modulated according to the selected gear ratio and clutch pedal release. The first senor (107) and the second sensor (108) continuously measures speed of the engine (101) and the transmission system (103) respectively. The measured speed values are continuously transmitted to the electronic control unit (106). Wherein the electronic control unit (106) estimates the clutch slip, the operating gear ratio and actual engine load as a function of clutch slip, for the measured speed values it received. Furthermore, the electronic control unit (106) compare the estimated values for the measured speed values with the stored value. according to the selected gear ratio and clutch pedal release. The first senor (107) and the second sensor (108) continuously measures speed of the engine (101) and the transmission system (103) respectively. The measured speed values are continuously transmitted to the electronic control unit (106). Wherein the electronic control unit (106) estimates the clutch slip, the operating gear ratio and actual engine load as a function of clutch slip, for the measured speed values it received. Furthermore, the electronic control unit (106) compare the estimated values for the measured speed values with the stored value. If the estimated values for the measured speed values are lower than the stored value, the electronic control unit (106) conveys the pressure control signal to the reverse valve in the fluid valve block (105), to disengage the reverse clutch in the clutch unit (102), either fully or partially according to the selected gear ratio and clutch pedal release, to avoid the engine stall.
The method and system of transmission control of the present invention eliminates the additional requirement of sensors. This system also eliminates the requirement of various position sensors. Since less sensors are used cost of the control system is drastically reduced. The present invention also allow the operator of the vehicle to launch pull away at any speed ratio without engine stall and thus averts the hazardous accident, which may occur due to engine stall.
It will be apparent to a person skilled in the art that the above description is for illustrative purposes only and should not be considered as limiting. Various modifications, additions, alterations, and improvements without deviating from the spirit and the scope of the invention may be made by a person skilled in the art.