Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
  • G01L3/00—Measuring torque, work, mechanical power, or mechanical efficiency, in general
  • G01L3/24—Devices for determining the value of power, e.g. by measuring and simultaneously multiplying the values of torque and revolutions per unit of time, by multiplying the values of tractive or propulsive force and velocity

Definitions

• the present invention relates to a device and a method for determining the mechanical power of a machine so as to allow in particular its control and adjustment.
• This method is not compatible with current needs and it is necessary to be able to precisely determine the mechanical power developed by a machine, to be able to control the variations of this power during operation and under load in order to be able to adjust it by optimally by finding the greatest power for a given number of revolutions.
• the device must be compact, easy to implement, clean, of a cost price compatible with that of the machines, precise in the results and versatile in order to receive the different models of the different brands.
• test bench comprises a transmission means which can be connected to the power take-off of the engine to be tested and an oil pump driven by this transmission means.
• the pump is interposed in a closed hydraulic circuit and includes an adjustable throttle valve, a pressure measurement device, a coolable oil tank, as well as a conduit connecting these parts, the transmission means being connected to an indicator. of the speed of rotation.
• the flow in the closed hydraulic circuit, the speed of rotation, the measurement of the flow and pressure are entered in a microprocessor which displays the values supplied separately and / or in a relation intended to establish the power, one of the values measurements supplied to the microprocessor, being multipliable by a factor corresponding to the efficiency of the oil pump.
• the present invention aims to create a device for determining the mechanical power of a machine, in particular for its control and adjustment, which comprises a test bench made up of simple, reliable elements, of low cost price. high and which makes it possible to reproducibly determine the mechanical powers of the machine by displaying these powers and the corresponding speed of rotation, the precision obtained being of the order of a few percent.
• the device for determining the mechanical power of a machine comprises a test bench consisting of a machine support with mechanical drive, a hydraulic pump driven by a transmission shaft connecting this pump to the machine, a tachometer to measure the speed of rotation of the shaft of the shaft drive, a closed circuit on either side of a tank, circuit on which the pump are interposed, pressure measurement means at the outlet of the hydraulic pump, a shutter with variable passage section disposed on the circuit downstream of the pump in the direction of circulation of the fluid and upstream of the reservoir and, this device is characterized in that it comprises first means for measuring the temperature T1 of the fluid arranged upstream of the hydraulic pump and second means for measuring the temperature of the fluid disposed downstream of the hydraulic pump and upstream of the shutter with variable passage section so as to determine the mechanical power of the machine.
• the device is characterized in that the test bench comprises means for calculating the mechanical power of the machine and means for displaying this power and the speed of rotation so to be able to adjust the machine to obtain the highest power for a given speed.
• the test bench comprises a machine support and a mechanical connection between the machine and the drive shaft.
• the mechanical connection is the cutting chain of the chainsaw from which the guide has been removed, which cooperates with one of the pinions of a set of pinions secured to the transmission shaft.
• the chainsaw support is also movable in translation so that the chain rotates in the plane of the associated pinion.
• the present invention also relates to a method for determining the mechanical power of a machine by means of the device defined above which is characterized in that knowing n the rotational speed of the hydraulic pump, K a form coefficient which takes into account the transfer coefficient h, S the surface of the pump body and that of the circuit tube included between the temperature measurement points T 1 and T 2 , the average density of the hydraulic fluid, C p the average specific heat, P 1 the absolute pressure at the pump discharge, P 0 and T 0 respectively the atmospheric pressure and the ambient temperature and v the unit volume of the pump per pump revolution hydraulic, we apply the relation:
• the method is also characterized in that the speed of rotation of the machine and the speed of rotation of the pump shaft are linked by a coefficient k corresponding to the transmission ratio.
• FIG. 1 a block diagram of the device according to the invention
• FIG. 2 is a schematic top view of the device applied to the power measurement of a chainsaw
• FIG. 3 is a schematic side elevational view of the device applied to the power measurement of a chainsaw.
• FIG. 1 shows a functional diagram of the device according to the invention.
• the machine 10 rotates a drive shaft 12 integral with the shaft of a gear pump 14 disposed on a hydraulic circuit 16.
• This hydraulic circuit comprises a reservoir 18 containing hydraulic fluid 20 two temperature probes 22 and 24 respectively disposed immediately upstream of the gear pump 14 and immediately downstream thereof, means 26 for measuring the absolute pressure delivered by the pump, a variable section shutter 28 disposed downstream of the pressure measurement means and the cooling means 30 of the hydraulic fluid disposed between the variable section shutter and the reservoir 18.
• the entire device is completed by a tachometer 32 for determining the speed of rotation of the drive shaft.
• Such a calculation can be carried out by means of a microprocessor 34, as represented in FIG. 1, in which the values of the constants have previously been stored and which recalculates the above formula after reception of the values of each of the measurements of speed, temperature and pressure.
• the microprocessor is completed by a display device 36 which displays any of the parameters measured but more particularly the power determined by the calculation as well as the machine speed expressed in revolutions per minute.
• FIG. 2 In Figure 2 is shown, seen from above, a frame 40, the mechanical transmission means 42 and the hydraulic means 44 for loading.
• the mechanical means 42 comprise a plate 46 movable in translation on two guides 48 and displaceable by means of a crank 50 thanks to a screw-nut system.
• fixing means 52 of the machine 54 in this case a chainsaw.
• the long chain guide is replaced by a short guide 56 while the chain 58 cooperates with one of the sprockets 60 of a set of sprockets 62.
• the different sprockets 60 of the set 62 make it possible to adapt the different chain types based on brands.
• the pinion assembly 62 is integral with a drive shaft 64 mounted rotating in the bearings 66 integral with the frame.
• a transmission member 68 comprising a set of pulleys 70 and belts 72.
• a tachometer 78 is also mounted on the transmission shaft 64 so as to be able to measure the speed of rotation of this shaft.
• the hydraulic means 44 comprise a gear pump 80, interposed in a hydraulic circuit 82 comprising a pipe 84 which plunges into a tank 86, provided with a non-return valve 88 upstream of the hydraulic pump 80 as well as a first thermocouple 90 intended to measure the temperature T 1 immediately upstream of the hydraulic pump 80.
• the pipe 84 is also provided with a second thermocouple 92 intended to measure the temperature T 2 immediately downstream of the hydraulic pump 80.
• a pressure sensor 94 In series on the pipe 84, there is provided a pressure sensor 94, a variable section shutter 96, successively a radiator 98 cooled by a motor-fan unit 97 and a non-return valve 100 immediately upstream of the tank 86 so as to close the circuit.
• the hydraulic pump 80 is rotated by a shaft 102, integral with the driven pulleys 70.
• the device is completed by a display screen 104 arranged above the frame 40 so as to be readable by the user, this screen being located in an ergonomic position.
• This screen is also associated with calculation means 103 comprising a microprocessor and memories.
• the user fixes the machine 54 on the plate 46 after having removed in the case of a chainsaw the long guide of the chain. It engages the chain 58 on the pinion 60 of the pinion assembly 62 corresponding to the type of chain by adjusting the plate 46 using the crank 50 so that the chain rotates in the plane of the corresponding pinion.
• the entire device is energized while the user starts the test machine 54.
• the coupling clutch 74 is in the disengaged position thanks to the lever 76 so that the machine 54 drives the set of pinions 62 and the transmission shaft 64 without driving the pulleys 70 of the transmission member 68.
• the coupling clutch 74 makes it possible to drive the set of pulleys 70 and by means of the shaft 102 the gears of the pump 80.
• the pump 80 draws hydraulic fluid from the tank 86 and discharges along arrow 85 into the line 84 of the hydraulic circuit 82.
• the fluid then passes through the variable-section shutter 96 after its pressure has been previously measured by the pressure sensor 94.
• the fluid then enters the radiator 98 where it is cooled by the air emitted by the motor-fan unit 97 to be returned to the tank 86.
• the non-return valves 88 and 100 prevent any return and any defusing of the pump 80.
• the different parameters, speed measured by the tachometer 78, upstream and downstream temperature measured by the thermocouples 90, 92 and pressure measured by the sensor 94 are sent to the microprocessor 103 which processes them and according to them of the selected display selection and shows the values on the screen 104.
• the repairer can maintain a constant speed by continuously accelerating the machine and adjust by example the combustion engine combustion engine so that the power is maximum for a given speed.
• the advantages of this device are numerous since first of all it can be used instantly for a measurement without waiting for a rise in temperature, level equalization or other.
• the installation of the machine on the device is almost instantaneous and in the case of chainsaws these machines can be tested in conditions very close to reality, since the power measurement is well measured on the chain and not directly at the output of the motor shaft with load.
• thermocouples which are very inexpensive, highly reliable and very precise sensors.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Combustion & Propulsion (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Testing Of Devices, Machine Parts, Or Other Structures Thereof (AREA)
• Control Of Positive-Displacement Pumps (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=9394282

Family Applications (1)

Country Status (3)

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Family Cites Families (4)

• 1990
  • 1990-03-01 FR FR9002585A patent/FR2659140A1/fr active Granted
• 1991
  • 1991-03-01 EP EP19910906601 patent/EP0471835A1/fr not_active Withdrawn
  • 1991-03-01 WO PCT/FR1991/000169 patent/WO1991013330A1/fr not_active Application Discontinuation

Non-Patent Citations (1)

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