A METHOD AND DEVICE FOR A REAL TIME MEASUREMENT OF OUTPUT TORQUE OF AN AUTOMOBILE ENGINE

Abstract: This invention describes a device for a real time measurement of torque output of an automobile engine. The device measures the deformation of damper springs of planar clutch plate and interpretes the deformation as the output torque while the automobile is running on the road. This device is composed of i) a planar disc clutch plate which includes damper springs, ii) a set of winglets and columns which are welded on the clutch plate, iii) signal pick-up sensor.

Description: Title of Invention A method and device for a real time measurement of output torque of an automobile engine. Existing technology in the category of invention One of the most important task of an engine development is to maximize the output power of the engine while the fuel consumption is minimized. To achieve this goal, the measurement of engine output torque is essential. Yet currently available technologies applicable to an automobile engine measures the revolutionary speed(rpm) and not the output torque while the engine is in operation. Power is, by definition, torque multiplied by the angular velocity. Torque measurement, at present, requires special set up of equipments. There are basically two ways of torque measurements. The most common method is the measurement of power by measuring the dissipation, angular velocity is measured separately; torque is acquired by dividing power by the angular velocity. The other method is the measurement of the minute twist of the axle by means of strain gauge attachment on the surface of the axle and bringing out the signal by incorporating slip rings on the axle. Both of the above methods is applicable only when the engines are tested on the test bench, but not when the engine is mounted on an automobile. A recently reported new technology makes use of magneto-elasticity of certain materials. This technology is also a measurement of minute twist of the axle, yet it is applicable for the real time measurement during the operation of the engine. Magneto-elasticity measurement requires some modification of the axle on the power train. Technical Objectives of this invention This invention presents the method of detecting instantaneous torque output of an automobile engine while the engine is in operation mounted on the automobile. The measurement of precise torque output enables one to facilitate a feed-back control in the engine control unit. Instantaneous torque measurement may provide the information on the state of health of the engine as well. This invention accomplishes the torque measurement by sensing the deformation of damper springs which are parts of the clutch plate. When the automobile engine delivers power to the transmission gear box, the torque is relayed by the damper springs of the clutch plate. The springs shorten their lengths proportionally to the torque they are relaying to the transmission. This invention provides the method of measuring the degree of shortening of the springs non-contactively and bringing the information out from the interior of the clutch assembly while the clutch plate is rotating together with the engine shaft. Disclosure of invention Description of Figures Fig.l. Diagram of a planar clutch assembly - 2 - Fig.2. Diagram of the blown out pieces of a clutch plate incorporating the winglets and columns of this invention. Fig.3. Cross- sectional view of the clutch plate assembled. Fig .4. Partially cut out view of the clutch plate when no torque is applied. Fig .5. Partially cut out view of the clutch plate when torque is applied. Fig .6. The shape of the damping spring incorporated with the clutch plate. Fig.7. Side view of axle guide tube. Fig.8. Cut away view of the axle guide tube when assembled. Fig.9. Output signal of the pickup sensor. Fig.10. One example output signal of this invention. Definitions of the numbered parts on the figures 1 clutch plate 2 axle of engine 3 : flywheel 4 pressure plate 5 throw-out bearing cap 6 : clutch housing 7 clutch axle 8 axle guide tube 10 clutch base plate 11 rivet hole 12 : spring well 13 friction surface(plate) 20 teeth -body 21 : spring well 22 small column 23 damper spring 30 : clutch top plate 31 : rivet hole 32 spring well 33 : rivet 34 : winglet 40 pickup sensor 41 : connecting wire 42 : placement well 43 wire trough Description of invention Referring to Fig.l, the clutch plated ), which relays the rotational power of the engine shaft (2) to the clutch shaft(7) is located between the flywheel(3) and the pressure plate(4). When the pressure plate(4) applies - 3 pressure, the clutch plate is pressed against the flywheel(3) and the clutch plate is made to rotate with the flywheel, and force the clutch shaft(7) to rotate together. When the pressure plate is retracted to relieve the pressure, the clutch plate together with the clutch shaft does not receive the rotational power from the engine. Clutch plate is composed of several parts as shown in Figures 2 and 3: base plate(lθ), teeth -body (20) and top plate(30). Rivets(33) fasten the top and base plates through the rivet holes(ll)(31). The teeth-body is kept between the two plates, but is free to rotate a small angle between the rivets. The spring wells (12) (21) (32) are aligned together and captures the damper springs(23). Friction surfaces(13) are incorporated on the base plate. When the rotational power of the engine is delivered to the base plate through the flywheel(3) and the pressure plate(4), the force acts on the damper springs to contract. The springs in turn press against the teeth-body. The teeth-body turns the clutch shaft which passes through its center. This configuration permits the passage of the engine power to the clutch shaft using the damper springs as relaying agent. For the purpose of this invention, two augmentation are incorporated with the clutch plate. They are the small columns(22) on the teeth-body and the winglets(34) on the top plate, as shown in figure 2 and 3. In Fig.2, six of the small columns are welded on the teeth-body in equal angular spaces forming a circle, six of the winglets are placed on the top plate forming a circle. Fig .4 shows the relative positioning of the columns and the winglets on the finished clutch plate. The numbers of the columns and winglets can be altered depending on the specifics of design needs. Fig.5 shows that the columns on the teeth-body are slightly displaced from the original places. This happens when the springs are forced to contract due to the force which these springs are relaying from the engine to the clutch shaft. The measurement of torque is accomplished by detecting the angular displacement of these augmentation pieces, and bringing the detected signals to outside of the clutch assembly. Fig.7 shows the axle guide tube(8) which is slightly modified for the purpose of this invention. The modification is the incorporation of the placement well (42) and the wire trough(43). A pick-up sensor(40) is mounted in the placement well and the lead wires from the sensor are brought out through the wire trough. For certain applications more than one pick-up sensor may be needed, and the number of placement wells and wire troughs can increase with the number of sensors. When the clutch housing is bolted in place, the pick-up sensor which sits inside the placement well is situated inside periphery of the small columns. The axle guide tube is bolt mounted inside the clutch housing and does not rotate, while the clutch shaft which passes through the guide tube and connects to the teeth body-rotates with the clutch plate. The small columns(22) and winglets(34) rotate with the clutch plate and they pass over the surface of the pick-up sensor. When the columns and winglets pass over the pick-up sensor, they generate signals which are as shown in Fig.9. The taller pulses represent signals from the small columns which are closer to the surface of the pick-up sensor, and the small pulses represent the signals from the winglets. The signals are measured in terms of time intervals of the pieces passing over the sensor. When no torque is applied the chain of pulses looks like Fig.9,A. When torque is applied the pulse chain looks like Fig.9.B. The displacement of small pulse in the figure increases proportionally when the torque increases. The measured displacement can be converted to torque values by appropriate conversion formula. - 5 The number of pick-up sensor(40) can be increased such that they are placed around the circumference of the axle guide tube(8). With one pick up sensor, the number of data gathering per one revolution of the engine is limited to the pairs number of the columns(22) and winglets(34). With six pairs as shown in figure 4 and 5, six data points are gathered for each revolution of the engine, or one datum point for every 60 degrees turn. If the number of pick-up sensor(40) is increased to 4, then the data will be available for every 15 degrees turn. Fig.10 shows a simulated output torque variations as function of the rotational angle of a 4- stroke 4 cylinder engine. Part A in the figure is an ideal case, and part B shows a case when the number 2 cylinder is partially misfiring. The circles on the figure indicates the data points acquired for every 15 degrees turn. The figure shows that real time instantaneous detection of torque can be used to diagnose engine performance and even identify the cylinder that is misfiring. Benefits from this invention The output power of an automobile engine is function of many parameters: amount of intake air, fuel-air mix ratio, ignition timing, road condition (loading) etc. The existing technology which measures the rotational speed and the above parameters controls the engine by heuristic approach. The method may need improvements. By measuring the output torque instantaneously as this invention enables, a feed-back control can be applied to achieve the best performance of an engine. - 6

Claims: claims claim 1 : Relating to the process of measuring torque output of an automobile engine instantaneously in real time, the deformation of the damper springs in the clutch plate are sensed and converted to the output torque value. claim 2 - Relating to the clutch plate, small columns are welded on the teeth body and equal number of winglets are welded on the top plate to facilitate angular displacement measurements. claim 3 : Relating to the non-contact sensing of the signal, the pick-up sensor produces signals that are measured in time intervals. The time interval signals are converted to torque values by appropriate conversion formula. AMENDED CLAIMS [received by the International Bureau on 30 September 1999 (30.09.99); original claims 1-3 cancelled; new claims 4-6 added (2 pages)] A device for a real time measurement of torque output from an engine to a transmission of an automobile comprising a plate type clutch with a clutch plate for intermitting the engine power, a clutch shaft for connecting said clutch plate to a transmission, and an axle guide tube for surrounding said clutch shaft over a length of said clutch shaft, said clutch plate comprising a lower body member with annular frictional materials attached along peripheries on both sides thereof and formed with a first aperture at a central portion thereof, an intermediate body member with a hub penetrated into and attached to said intermediate body member at a central portion thereof, said hub being adapted for coupling with said clutch shaft and a lower portion of said hub being inserted into said first aperture, said intermediate body member being adapted to be positioned onto said lower body member, and an upper body member formed with a second aperture at a central portion thereof and adapted to be positioned onto said intermediate body member, an upper portion of said hub being inserted into said second aperture, said lower and upper body members being fixedly fastened together with said intermediate body member interposed therebetween to be circumferentially displaced relative to said lower and upper body members by a damper spring means, characterized in that said device includes signal-producing reference means formed on said clutch plate, at least one sensor mounted into a mounting aperture in a leading end portion of said axle guide tube to be positioned radially inside said signal-producing reference means and to face said signal-producing reference means, and computing means for receiving a signal output from said sensor and for computing the engine torque based on said signal, said signal-producing reference means includes a first plurality of axially extending posts formed equidistantly around a periphery of said - 8 - upper portion of said hub, and a second plurality of axially extending posts formed equidistantly around a circumference of said second aperture of said upper body member, said first posts being disposed radially inside said second posts. claim 5: (added) The device as claimed in Claim 1 , wherein said axle guide tube is formed with a trough which is contiguous to said sensor mounting aperture and extends at a predetermined length over the length of said axle guide tube, and wherein a pair of wires for transmitting said signal output from said sensor to said computing means is fitted into said trough. claim 6: (added) The device as claimed in Claim 1 , each of said first posts is located equiangularly relative to circumferentially adjacent two second posts. - 9 - Statement under Article 19 Claims 1-3 have been canceled. New Claims 4-6 have been added to more specifically set forth and claim the subject invention. The new claims are fully supported by the description and do not exceed the disclosure m the international application as it was originally filed. The specification and drawings remain unchanged. Newly added independent claim 4 states a device for a real time measurement of torque output from an engine to a transmission of an automobile, wherein signal -producing reference means are formed on a clutch plate and at least one sensor is mounted into a mounting aperture m a leading end portion of an axle guide tube to be positioned radially inside the signal -producing reference means and to face the signal -producing reference means. The present invention is not suggested by the citation, US 4 683 746 A, m the international search report. 10

Inventors: CHANG KEUN-HO, CHANG PETER TAEHWAN, CHANG THOMAS GIHWAN, CHANG, KEUN-HO, CHANG, PETER, TAEHWAN, CHANG, THOMAS, GIHWAN
Applicants: CHANG KEUN HO, CHANG PETER TAEHWAN, CHANG THOMAS GIHWAN, CHANG, KEUN-HO, CHANG, PETER, TAEHWAN, CHANG, THOMAS, GIHWAN
Application year: 1999
Main classification: G01L3
IPC codes: G01L3