WO2018235003A1

WO2018235003A1 - Spark angle control system

Info

Publication number: WO2018235003A1
Application number: PCT/IB2018/054525
Authority: WO
Inventors: Suvanam Venkata SAI VETHA HAVYA; Janakiraman Ramamoorthi; Sachin Ramachandra Phadnis
Original assignee: Tvs Motor Company Limited
Priority date: 2017-06-20
Filing date: 2018-06-20
Publication date: 2018-12-27

Abstract

The present invention relates to a system used to control the temperature within an internal combustion engine (125) and improve the life of the coolant used. The system comprises of a thermistor (310) and a pulser coil (305) provided for the internal combustion engine (125). A TCI unit (315) takes and compares the speed of the engine and temperature. Based on the reading it checks it with pre-loaded data and in case the value is high, the spark angle is changed to reduce the combustion and temperature.

Description

SPARK ANGLE CONTROL SYSTEM TECHNICAL FIELD

[0001] The present subject matter relates generally to an internal combustion engine, and more particularly to a method which keeps the engine temperature in check and enhances the life of engine coolant for the internal combustion engine.

BACKGROUND

[0001] Generally, a saddle type vehicle comprises of a frame assembly extending rearwardly from a head tube. The frame assembly acts as a skeleton and a structural member for the vehicle that supports the vehicle loads. A front wheel is connected to a front portion of the frame assembly through one or more front suspension(s). The frame assembly extends towards a rear portion of the vehicle. A rear wheel is connected to a frame assembly through one or more rear suspension(s). The frame assembly comprises of a power train system e.g. an engine assembly & / or a motor with energy source etc. mounted to it. The engine assembly is functionally connected to the rear wheel, which provides forward motion to the vehicle. A muffler assembly is provided at a lateral side of the vehicle mounted to the frame assembly or the vehicle through a mounting bracket. Typically, plurality of panels is mounted to the frame assembly of the vehicle that covers various vehicle parts mounted thereon.

[0002] Typically, the engine assembly is mounted to the frame assembly of the vehicle. In case of an internal combustion (IC) engine, it might comprise of one or more cylinder bore(s), where combustion happens. The internal combustion (IC) engine, among other components, has a cylinder on top of which a cylinder head is mounted, and receives a reciprocating piston from the bottom. On combustion of the air-fuel mixture, the piston transfers the energy generated during combustion to a crankshaft through a connecting rod thereby driving the crankshaft. In this way, the reciprocatory motion of the piston is converted to rotary motion of the crankshaft. The crankshaft rotation then powers the vehicle.

[0003] The combustion of air fuel mixture inside the cylinder bore results in the reciprocating motion of the piston. Also, the combustion results in generation of heat. Generally, oil or the like is circulated through the aforementioned parts for lubrication. Due to the high temperature being generated oil being circulated is also subject to heating. Thus a constant check with respect to temperature of internal combustion engine and the oil being circulated is must.

[0004] Moreover due to the continuous running process, especially at a high power running condition the temperature of the internal combustion engine is very high. Such high temperatures are not ideal for a system. In fact, life of the engine coolant being used also takes a hit due to the high temperatures generated. Therefore different systems use different methods to control the temperature of the internal combustion engine within its safe limits. In furtherance to it some of the methods are implemented separately which only concentrate on enhancing life of the engine coolant being used.

[0005] To keep the engine temperature in check some of the systems use a radiator through which the coolant can be circulated, a sensor which notes the temperature of the engine based on which controlled coolant fluid is sent through a coolant flow control valve. There are few systems which have two jackets of coolants being used, where the first jacket of coolant is normally used and the second jacket is used only when the sensor detects a high temperature in the internal combustion engine. One of the other systems in this respect implements a shutter on the radiator which opens and closes based on the engine temperature so as to provide a passage for the air to flow and enhance the efficiency of the coolant used. Another system in this respect implements a series of branches which carry the engine oil/coolant and are connected to one another. The branches expand when the temperature is high resulting in increased supply of coolant to keep the temperature in check.

[0006] Moreover when it comes to enhancing life of the engine coolant being used, the most common solution for it has been changing the chemical composition of the coolant. Some of the systems concentrate on making it an acid based antifreeze composition, whereas some of them try increasing the glycol weight ratio. But there has not been a system which keeps the temperature of the internal combustion in check and enhances the life of the coolant as well simultaneously.

[0007] However, all these methods cited in the prior art face some or the other problem in their functioning. Most of them propose for addition of an extra element in the system which is not feasible. Maintenance and installation of the extra element is also an issue, whereas continuous and precise functioning of the system is a challenge in itself. There are also chances that so many systems might not work in sync resulting in failure or faulty results. The extra cost of changing the coolant composition is another such aspect here. In fact, as mentioned earlier there is no known system which might work and solve both the problems using a single system in a simple yet precise manner.

[0008] There is therefore a need to provide an alternative system which incorporates a method to keep the engine temperature in check and also improves the life for engine coolant being used simultaneously. It is yet another objective of the present subject matter to make the system a simple yet precise one without adding much extra elements to it.

BRIEF DESCRIPTION OF DRAWINGS

[0002] The detailed description of the present subject matter is described with reference to the accompanying figures. Same numbers are used throughout the drawings to reference like features and components.

[0003] Fig. 1 illustrates a left side view of an exemplary two-wheeled vehicle, in accordance with an embodiment of present subject matter. [0004] Fig. 2 illustrates a sectional view of the right side of an exemplary power unit, in accordance with the embodiment of Fig. 1.

[0005] Fig. 3 depicts a block diagram of the spark angle control system, in accordance with the embodiment of Fig. 2.

[0006] Fig. 4 illustrates a method of operation of the spark angle control system, in accordance with the embodiment of Fig. 3.

[0007] Fig. 5 depicts an exemplary graph for spark angle plotted against engine RPM, in accordance with another embodiment of the present subject matter.

[0008] Fig. 6 depicts a block diagram of a control system, in accordance with another embodiment of the present subject matter.

DETAILED DESCRIPTION

[0009] Typically, a saddle type motor vehicle is operated through an engine assembly mounted to the frame assembly in a front portion and a fuel tank disposed above the engine assembly. Conventionally, internal combustion engine assembly includes a crankcase, a cylinder block coupled to the crankcase, and a cylinder head mounted on the upper part of the cylinder block. Air fuel mixture is supplied to the engine assembly by means of a carburetor. Thereafter combustion of the air fuel mixture takes place so that a piston disposed in the engine assembly is set into motion. The piston is operated in a linear motion, after which said linear motion is converted to a rotational motion, wherein said rotational motion is transferred to the rear wheel finally resulting into motion of the vehicle. This mechanism also results in generation of power and torque by the engine assembly.

[00010] The carburetor sends air fuel mixture for combustion process. During the expansion stroke of the piston the mixture comes in through an inlet valve. Whereas during the exhaust stroke the exhaust valve opens to send the remaining exhaust. This is a continuous process to drive the vehicle and the process becomes faster as the vehicle is running and gains speed, thus resulting in excess of heat generation in the internal combustion engine. Generally engine coolant is supplied in the internal combustion engine to pacify the excess heat generated and reduce the temperature. During this process life of the engine coolant being used also takes a hit. It might also happen that the engine coolant being used loses its efficiency in cases of such extreme temperatures.

[00011] To solve some of the problems stated above and keep the engine temperature in check one such known system implemented a coolant control valve which is opened and closed based on the readings of a temperature sensor disposed in the engine assembly. One of the other such known system used two jackets of coolant, first one for normal running condition and the other one used for high intense running conditions. In one of the other cases a shutter was placed on a radiator through which air was supplied to increase the efficiency of the coolant during high speed conditions. Another such known system in this respect implemented various interconnected branches through which coolant is supplied to the engine assembly in such a way that these branches would expand when the temperature is high so as to increase the flow of the coolant. Changing the composition of the coolant is one of the other known methods through which efficiency and life of the coolant was tried to be increased.

[00012] However, all the methods stated above in the prior art face some or the other problem. In one embodiment, the increased number of parts, components and valves makes the system complex. It is not feasible as well since maintenance of such a complex assembly becomes an issue in itself and the probability of getting a precise result also decreases. In fact, there is a high possibility of all the components not working in sync with each other. There is no efficient system which tries keeping a check on the engine temperature and simultaneously tries enhancing life of the engine coolant.

[00013] Therefore, the present subject matter overcomes the above stated problems in the prior art. One of the objectives of the present subject matter is to control the engine temperature and enhance the life of the engine coolant as well. Another objective of the present subject matter is to provide a method which does not complicate the system, removes the requirement of extra elements and keeps it simple yet precise.

[00014] In an embodiment in accordance with the present subject matter, a saddle type vehicle is employed with a system which incorporates a method to control the engine temperature and enhances life of the engine oil/coolant used.

[00015] Typically an internal combustion engine gets heated due to its continuous working. The temperature in the internal combustion is maximum in case of high rotations per minute (RPM) when a high power demand is being met. Excessive temperature in the internal combustion engine means excessive heating of the engine coolant too which reduces its life cycle. Therefore, the excess heat generated at high RPM, when power load is maximum, is something which needs to be controlled.

[00016] In an embodiment, firstly temperature of the engine assembly is measured through a temperature sensing means including a thermistor placed in the crankcase assembly. A thermistor notes the temperature at the wall of the crankcase assembly and an input in form of resistance generated by the equivalent temperature of the crankcase assembly is sent to a transistor controlled ignition (TCI) unit. In an embodiment, the TCI unit also receives inputs from an engine status means that includes a pulser coil depicting the current engine load condition and RPM. A preloaded set of spark advance look up data is also fed in the TCI unit.

[00017] In an embodiment, the TCI unit is continuously updated with present crankcase temperature, engine load and RPM. Using these inputs the TCI unit keeps a check on the present running condition of the engine assembly. The TCI unit also compares the inputs which it is receiving to the already fed spark advance look up data. By comparing both the sets the TCI unit keeps a record of how the power requirement of the vehicle is being met by proper spark timing in the engine assembly at a sufficient spark angle. In one embodiment, as the power requirement increases, the engine RPM, temperature and load also increases. The TCI unit keeps comparing both the sets of data to maintain the spark angle as per the requirement. But after a point when the temperature, engine RPM and load is very high beyond a threshold point the TCI unit varies the spark angle after comparing both the sets of data such that the spark angle is delayed as to what it should have normally been for that particular moment and RPM.

[00018] In an embodiment, the spark is delayed so that power output of the engine assembly is reduced. During a high RPM condition, working of the engine assembly becomes more rigorous resulting in an increased load. Therefore, at such particular moment the spark advance angle is varied so that even when the RPM is high the power requirement ratio is not met by the engine assembly. This releases the engine assembly from the excessive heating resulting in controlling of the engine assembly temperature also. In an embodiment, at a particular range of high engine RPM, engine load and temperature the TCI unit compares both the sets of data and calculates the difference which should be there between the new spark angle and what it should have been in normal circumstances. Based on such comparison and calculation the TCI unit sends signal to change the spark angle accordingly. As another embodiment of the present invention, it is possible to have a control unit equivalent to the TCI to control the throttle command for e.g. for an electric vehicle wherein the temperature of the motor or the energy source or both is being monitored & the command is being changed / altered based on the pre-fed look-up data.

[00019] Thus one of the objectives of the present subject matter is to provide a system which controls temperature of the engine assembly and enhances life of the engine coolant being used as well. In an embodiment, one of the other objectives of the present subject matter is to provide a system which uses a simple yet precise method without much extra elements being added to it. The present subject matter also provides a safe limit within which the engine load and RPM is controlled and maintained. In another embodiment, it is one of the obj ectives of the present subj ect matter to maintain the engine performance at an optimum level within the safe limits.

[00020] The aforesaid and other advantages of the present subject matter would be described in greater detail in conjunction with the figures in the following description.

[00021] In relation to the following description of embodiment(s), arrows as and where provided in the top right corner of each figure depicts direction with respect to the vehicle, wherein an arrow F denotes front direction, an arrow R indicates rear direction, an arrow Up denotes upward direction, an arrow Dw denotes downward direction. Also, an arrow with LH denotes a left side, and an arrow with RH denotes a right side. All aforementioned directions are with respect to the vehicle.

[00022] Fig. 1 illustrates a left side view of an exemplary two-wheeled vehicle, in accordance with an embodiment of the present subject matter. The vehicle (100) has a frame assembly (105) that includes a head tube (105 A), a main tube (105B) extending rearwardly downward from the head tube (105 A), and a pair of railing (105C) extending inclinedly rearward from a rear portion of the main tube (105B). A handlebar assembly (110) is connected to a front wheel (115) through one or more front suspension(s) (120). A steering shaft (not shown) connects the handlebar assembly (110) to the front suspension(s) (120). The steering shaft is rotatably journaled about the head tube 105A. Apower unit (125) including at least one of an internal combustion engine and/or a traction motor is disposed in a posterior portion of the vehicle (100). In the present embodiment, the IC engine is forwardly inclined i.e. a piston axis of the IC engine is forwardly inclined. In other embodiment, the IC engine can be a vertical type. Hereinafter, the terms power unit (125) and the IC engine are interchangeably used. The power unit (125) is functionally connected to a rear wheel (130) through a transmission system (not shown). The transmission system includes a continuously variable transmission or a fixed gear ratio transmission or automatic-manual transmission.

[00023] Further, the rear wheel (130) is connected to the frame assembly (105) through one or more rear suspension(s) (135). The power unit (125) is swingably mounted to the frame assembly (105) through a toggle link or the like. A seat assembly (140) is disposed above a utility box (not shown) and is supported by the pair of railing(s) (105C). A passenger grip (175) is provided posterior to the seat assembly (140) for pillion/passenger support.

[00024] Further, the vehicle (100) includes a front fender (150) covering at least a portion of the front wheel (115). In the present embodiment, a floorboard (145) is disposed at a step-through space and is supported by the main tube (105B). The user can operate the vehicle (100) by resting feet on the floorboard (145), in a sitting position. In an embodiment, a fuel tank (not shown) is disposed below the seat assembly (140). A rear fender (155) is covering at least a portion of the rear wheel (130). The vehicle (100) comprises of plurality of electrical/electronic components including a headlight (160A), a tail light (160B), a battery, a transistor controlled ignition (TCI) unit (not shown), an alternator (not shown), a starter motor (not shown). Further, the vehicle (100) includes a synchronous braking system, an anti- lock braking system, or a fuel injector.

[00025] The vehicle (100) includes plurality of panels (170) that include a front panel disposed in an anterior portion of the head tube (105A), a leg shield is disposed in a posterior portion of the head tube. A rear panel assembly (170) extending downwardly of the seat assembly (140) and extends rearward from a rear portion of the floorboard (145) towards a rear portion of the vehicle (100). The rear panel assembly (170) encloses the utility box. Also, the rear panel assembly (170) partially encloses the power unit (125). The IC engine (125) includes an air intake system (not shown), an air fuel supply system (not shown) that are coupled to an intake side of the IC engine (125) and are disposed on the IC engine (125). Also, an exhaust system (not shown) is coupled to exhaust side of the IC engine and the exhaust system extends towards one lateral side of the vehicle (100).

[0009] Fig. 2 depicts an isometric view of the right side of the power unit, in accordance with the embodiment depicted in Fig. 1. The power unit (125) includes a crankcase (125A) comprising at least two portions including plurality of apertures and mounting portion for rotatably supporting various components including a wheel shaft (125B). The crankshaft (not shown) is rotatably supported by the crankcase (125A) and the crankshaft (125B) is connected to a piston (not shown) having a reciprocating motion about a cylinder portion (CP) therein. The reciprocating motion of the piston is converted into a rotating motion of the crankshaft. The cylinder portion (CP) includes a cylinder body (125CA) and a cylinder head (125CB) that are supported by the crankcase (125A). The power unit (125) is swingably connected to the frame assembly (105) through an aperture portion (125D) provided on the crankcase (125 A). Furthermore, an ignition means including a spark plug (125F) is provided for creation of spark for combustion of air-fuel mixture. In an embodiment, the IC engine comprises of a temperature sensing means including a thermistor (310) (shown in Fig., 3) placed in the crankcase (125A) which acts a thermal sensor and sends resistance inputs to a TCI unit proportional to the surface temperature of the crankcase (125 A).

[00010] Fig. 3 depicts a block diagram of the spark angle control system (300), wherein the spark angle control system comprises of an engine status means including a pulser coil (305) which feeds input to the TCI unit (315), based on which the TCI unit (315) calculates the engine RPM and engine load. In an embodiment, the system comprises of a thermistor (310) which acts a thermal sensor and sends temperature based resistance value to the TCI unit (315), based on which the TCI unit (315) calculates the crankcase assembly temperature where the thermistor is placed. The TCI unit (315) is also pre fed with spark advance time maps (320) and data used for comparing it to the present running condition. Based on these comparisons and results the TCI unit (315) decides if the temperature, RPM, engine load and internal conditions are high enough and if it is the right time to vary the spark angle or not, and sends signal or command to the ignition unit (325) accordingly. The TCI unit (315) detects crankshaft location from pulser coil (305) input, gets spark advance and fires accordingly.

[00011] Fig. 4 depicts the method of operation of the spark angle control system (300), in accordance with the embodiment as depicted in Fig. 3. Speed of the vehicle (100) is controlled by the rider. With passing time and depending upon the circumstances if the rider feels so he accelerates the vehicle. This results in a larger throttle opening and increased RPM. Such conditions also result in increased engine load as the power requirement is increases, finally resulting in an increased temperature of the engine assembly.

[00012] The TCI unit (315) receives input from the pulser coil (305) based on which it calculates the engine RPM and engine load whereas it is also pre fed with spark angle and ignition maps (320) and data for further comparisons and calculations. The thermistor (310) acts as a thermal sensor and sends temperature based resistance values to the TCI unit (315) for temperature calculation. Based on the data calculated and data which has already been fed the TCI unit (315) compares and calculates whether it is the right time to vary the spark advance angle or not, and if it is so then by how much degree, and sends signals to the ignition unit (325) accordingly.

[00013] At step S405, the TCI unit (315) is pre fed with existing spark advance maps and data. After which at step S410 the TCI unit (315) receives data from the pulser coil (305) and at step S415 the TCI unit (315) calculates the engine RPM and engine load. Later at step S420 a temperature based resistance value is obtained from the thermistor. Once the resistance value is obtained, then at step S420 the TCI unit (315) calculates the temperature of the crankcase 125 A assembly from the resistance value of the thermistor, wherein the crankcase-temperature is dependent upon the engine temperature.

[00014] Furthermore, at step S425 the TCI unit (315) checks if the engine- temperature is greater than a threshold value or not. In case it is not, at step S430 is performed wherein there is no variation in the spark advance angle and the normal procedure is used. In case it is greater than the threshold value then the TCI unit (315) at step S435 compares the already calculated engine RPM and engine load data with the pre fed data. Based on the comparison TCI unit (315) decides by how much degrees does the spark advance angle needs to be varied at step S440 to achieve the optimal result and finally varies the spark advance angle at step S445.

[00015] Fig 5 depicts an exemplary graph for spark angle plotted against engine RPM, in accordance with an embodiment of the present subject matter. Typically As the vehicle' s speed increases so does the engine RPM with it. The TCI unit (315) gets data with respect to engine RPM from pulser coil whereas the spark angle is varied normally as per the engine RPM and the performance requirement. In one embodiment, the engine RPM triggers to a high value where it has been defined as point A. There are two patterns which diverge from point A, in one of them there is no change in the spark firing angle whereas in one of them it is reduced. Point A explains the instance when the TCI receives the temperature reading, in case of engine temperature being less than at least 130° c there in no change in spark firing angle and point C is reached. In case of temperature reading being more than at least 130° c there is a reduction in the spark firing angle bringing it down to point B. In an embodiment, the TCI combines value of engine RPM, engine load and temperature so as to vary the spark angle such that the engine performance is affected by not meeting the requirement at that moment resulting in reduced RPM and finally in reduced load and temperature. Thus this process also enhances the life of the engine coolant being used by curbing the engine temperature.

[00016] Fig. 6 depicts a block diagram of a control system, in accordance with another embodiment of the present subject matter. The temperature control system (500) includes a control unit (515) equivalent to the TCI unit as discussed above. The control unit (515) capable of modifying the motor operation depending temperature of the motor or the energy source or both, load on the motor, and rotational speed. Depending on the aforementioned parameters a pulse signal that is send to the motor, like a brush less direct current (BLDC) motor and thereby changing / altering the pulse signals sent to the motor. Moreover, the control unit (515) is capable of modifying the signal based on a pre-fed look-up data.

[00017] The temperature control system (500) includes a status sensing means like a position sensor (505). The data from the position sensor (505) is fed to the control unit (515). Further, the control unit (515) calculates the motor speed and load on the motor. Further, a thermistor/temperature sensing means (510) which acts a thermal sensor sends temperature based information to the unit (515). Based on the aforementioned information, the control unit (515) calculates the status of the motor. In one implementation, the control unit (515) may refer to pulse map (520) and the data used for comparing it to the present running condition. Based on these comparisons and the control unit (515) decides if the temperature, RPM, motor load and internal conditions are high enough and if it is the right time to vary the pulse signal, and sends signal or command to the pulse generation unit (525) accordingly. The pulse generation unit (525) can be a pulse wave modulator (PWM) unit. Accordingly, the control unit enables the motor acting as power unit to optimally cool down without the need for any additional modifications or variations to the motor.

[00018] It is to be understood that the aspects of the embodiments are not necessarily limited to the features described herein. Many modifications and variations of the present subject matter are possible in the light of above disclosure.

List of reference signs:

105A head tube 160 A headlight

105B pair of railings 160B tail light

110 handlebar assembly 170 plurality of panels

115 front wheel 30 175 passenger grip

120 front suspension CP cylinder portion

125 power unit 300 spark angle control system

125A crankcase 305 pulser coil

125B crankshaft 310 thermistor

125CA cylinder body 35 315 TCI unit

125CB cylinder head 320 time maps

130 rear wheel 325 ignition unit

135 rear suspension 505 position sensor

140 seat assembly 510 thermistor

145 floorboard 40 515 Control unit

150 front fender 520 pulse maps

155 rear fender 525 pulse generation unit

Claims

We Claim:

1. A temperature controlling system (300) for an internal combustion engine (125) comprising at least one spark plug (125F), wherein said system (300) comprising: at least one temperature sensing means acting as a thermal sensor placed in a crankcase assembly (125 A) enabling measurement of temperature of said internal combustion engine (125) through walls of said crankcase assembly (125A); and an engine status means disposed in said internal combustion engine (125) to identify one or more parameters with respect to running condition of said internal combustion engine (125); and

a control unit to enable variation of spark angle of said internal combustion engine (125) based on recording and comparing of values of said engine sensor means, said temperature sensing means and a pre-determined data.

2. The system (300) according to claim 1, wherein said temperature sensing means includes a thermistor sensor (310) that is placed in said crankcase (125A) to send resistance values equivalent to crankcase wall temperature.

3. The system (300) according to claim 1, wherein said control unit means includes a transistor control unit (315), which is enabled to determine load of said internal combustion engine (125) based on said one or more parameters of said engine status means, includes a pulser coil (305) and speed of said internal combustion engine (125).

4. The system (300) according to claim 1 or claim 3, wherein said transistor control unit (315) is fed with pre-loaded ignition maps and data acting as pre-determined data.

5. The system (300) according to claim 1, wherein sad transistor control unit (315) is provided to compare values of temperature, speed and load of said internal combustion engine (125) to said pre-determined ignition maps to decide the delay in spark angle.

6. A method for operating temperature controlling system (300) for an internal combustion engine (125), comprising steps of:

detecting temperature of an internal combustion engine (125) through an engine status means;

determining speed of said internal combustion engine (125) from said one or more parameters of an engine status means;

checking temperature of said internal combustion engine (125) to have crossed a threshold value;

comparing temperature and speed of internal combustion engine (125) to a set of pre-determined data to enable delay in spark angle for said internal combustion engine (125).

7. The method according to claim 6 further comprises of a step of determining load of said internal combustion engine (125) from said one or more parameters of said engine status means including a pulser coil (305) and speed of said internal combustion engine (125).

8. The method according to claim 6 further comprises of a step of comparing said pre-determined data to a combination of temperature, speed and load of said internal combustion engine (125) to delay spark angle in case temperature crosses said threshold value.

9. A temperature controlling system (500) for a power unit including a motor, said system (500) comprising:

at least one temperature sensing means (510) acting as a thermal sensor placed enabling measurement of temperature of said motor; and

a status sensing means disposed in said motor to identify one or more parameters with respect to running condition of said motor; and a control unit (515) to enable variation of pulse signal of said motor based on recording and comparing of values of said status sensing means, said temperature sensing means and a pre-determined data.

10. The temperature controlling system (500) for the power unit including the motor as claimed in claim 1, wherein said status sensing means includes a position senor (505) to provide a rotor position of the motor, said variation of pulse signal is done by a pulse generation unit (525), said pre-determined data includes a pulse map (520), and said temperature sensing means includes a thermistor (510).