Browse Topic: Magnetic clutches

Items (41)

Improving the design of automotive air conditioning compressors by predicting the minimum engagement voltage of electromagnetic clutches

2022-01-020603/29/2022

In order to insure passengers comfort, automotive air conditioning compressors are designed to be operational in case of low battery voltage. However, the “minimum engagement voltage” of compressors is mostly driven by designers’ know-how and rely extensively on laboratory tests, which can lead to two issues: Costly design modifications if problems are detected too late in the validation phase and the necessity to perform several design iterations before reaching the desired target. This paper presents the benefit of predicting the minimum engagement voltage where both of these drawbacks can be avoided, leading to a more robust design process. The method was tested on an electromagnetic clutch whose purpose is to engage the compressor when the air conditioning is turned on by passengers. The magnetic field generated by the clutch was estimated using an electromagnetic simulation software. Coil design parameters, materials magnetic properties, clutch assembly geometry and air gaps were

PLUY, Nicolas, Ohk, Changheon

Performance Optimization of Compressor Rotor Clutch Sub-assembly Using Electro- Magnetic Analysis

2018-01-048404/03/2018

Rotor Clutch sub-assembly is one of the very important sub-assemblies (S/A) of an automotive compressor as it delivers the required torque/power to run the compressor. It mainly consists of rotor and bearing, stator, hub and armature. Rotor is rotated by engine pulley through belt drive system, while stator housing has got number of coils winded around stator slot. The hub sub-assembly is attached to the compressor shaft via spline arrangement and bolted across. When direct current (DC) is supplied to the terminal of the rotor, an electromagnetic field is generated which causes to attract the hub part towards rotor. Once the hub and rotor gets engaged each other, torque is transmitted to the compressor shaft which then helps to complete the suction and compression of refrigerant gas and thus making the vapor cycle run to produce adequate cooling in the air-conditioning (AC) system. Hence it is most important to ensure adequate and even distribution of electromagnetic field which is

Meena, Avadhesh, Sen, Somnath, Meena, Avadhesh, Sen, Somnath

Modeling of Fixed Displacement Swash Plate Compressor: A Mathematical Approach towards Calculation of Shaft Torque and Volumetric Efficiency

2016-28-017202/01/2016

Rapid advent of mobile air conditioning industry has witnessed a wide use of fixed displacement swash plate compressor due to its small size, compact structure and light weight. An accurate prediction of volumetric efficiency and power of compressor at early stages of design serves as a very useful information for designer. No work regarding the power and volumetric efficiency prediction for double headed fixed displacement swash plate compressor is reported in the existing literature. This paper presents a mathematical model for a double acting fixed displacement swash plate compressor with the objective of evaluating the shaft torque and volumetric efficiency of compressor. Shaft torque, in turn is a measure of compressor power. The geometrical description of swash plate yields a kinematic model to obtain the piston displacement as an explicit function of angle of rotation of shaft. A methodology is presented to evaluate in cylinder gas pressures as a function of angle of rotation of

Srivastava, Praharsh, Sharma, Kamal, Jha, Raushan

A New Control Scheme for Automated Manual Transmission with Electromagnetic Powder Clutch

2015-24-254709/06/2015

This study aims to provide modeling and control approaches for automated manual passenger and commercial vehicle transmissions in order to improve the overall disengagement-gear shifting-engagement performance using electromagnetic powder clutch (EMPC). The rationale behind selecting this clutch is its rapid behavior. During the modeling procedure of the EMPC, the analogy between this type of clutches and dry plate friction clutches has been exploited and a simple control method is proposed. The study also includes modeling method for gear shifting and selecting mechanisms of the automated manual transmission gearbox as well as development and implementation of controllers which is designed for these mechanisms. Automated manual transmission gearbox is utilized due to its combination of ease of construction and ability for electronic automation.

Ergenc, Ali Fuat, Ergenc, Alp, Erdogan, Caner, Dumanli, Alper

A Rule-Based Control for Fuel-Efficient Automotive Air Conditioning Systems

2015-01-036604/14/2015

In a conventional passenger vehicle, the AC system is the largest ancillary load. This paper proposes a novel control strategy to reduce the energy consumption of the air conditioning system of a conventional passenger car. The problem of reducing the parasitic load of the AC system is first approached as a multi-objective optimization problem. Starting from a validated control-oriented model of an automotive AC system, an optimization problem is formalized to achieve the best possible fuel economy over a regulatory driving cycle, while guaranteeing the passenger comfort in terms of cabin temperature and reduce the wear of the components. To complete the formulation of the problem, a set of constraints on the pressure in the heat exchanger are defined to guarantee the safe operation of the system. The Dynamic Programming (DP), a numerical optimization technique, is then used to obtain the optimal solution in form of a control sequence over a prescribed driving cycle. The solution of

Rostiti, Cristian, Stockar, Stephanie, Canova, Marcello

NVH Integration of Twin Charger Direct Injected Gasoline Engine

2014-01-208706/30/2014

The increased focus and demands on the reduction of fuel consumption and CO2 requires the automotive industry to develop and introduce new and more energy efficient powertrain concepts. The extensive utilisation of downsizing concepts, such as boosting, leads to significant challenges in noise, vibration and harshness (NVH) integration. This is in conflict with the market expectation on the vehicle's acoustic refinement, which plays an increasingly important role in terms of product perception, especially in the premium or luxury segment. The introduction of the twin charger boosting system, i.e. combining super and turbo charging devices, enables downsizing/speeding in order to achieve improved fuel economy as well as short time-to-torque, while maintaining high driving dynamics. This concept requires also extensive consideration to NVH integration. The NVH challenges when integrating a roots type supercharger are very extensive. The high frequency source characteristics of the

Shah, Ashish, Lennström, David, Sturesson, Per-Olof, Easterling, William

Development of Third-Generation Electronically Controlled AWD Coupling with New High-Performance Electromagnetic Clutch

2014-01-171604/01/2014

This paper describes the development of the new third-generation electronically controlled all-wheel drive (AWD) coupling that achieves drastically improved drag torque performance and torque accuracy at low temperatures, and contributes to higher fuel efficiency through weight reduction in the driveline. One issue for electronically controlled AWD couplings is an increase in torque due to higher lubricant viscosity at low temperatures, especially below 0°C, because of clutch slide with the lubricant sealed inside the couplings. The developed third-generation electronically controlled AWD coupling addresses this issue by focusing on the surface texture of the electromagnetic clutch. The third-generation coupling also restricts the torque increase by actively utilizing the dynamic pressure between the clutch plates and increasing the clearance of the clutch plates at low temperatures where viscosity increases. This enables further weight reduction in the driveline. In order to reduce

Ando, Junji, Tsuda, Takuya, Ando, Hiroyuki, Niikawa, Yoshihiro, Suzuki, Kunihiko

A Simple Mechanism for AC Compressor Operation

2013-01-287911/27/2013

One of the most essential components of automotive HVAC system is compressor. In a vehicle it is directly mounted on the engine. It derives power from the engine feed system to keep refrigerant moving in the HVAC system of the vehicle. It is also essential to complete the vapor compression cycle. During the operation, it causes considerable load on the engine and thus results in lower fuel efficiency and higher pollution. There are several types of compressors available globally. According to construction it can be classified as reciprocating piston type, scroll type and rotary vane type. The reciprocating piston types of compressors are further classified as fixed displacement and variable displacement. Normally the fixed displacement compressors have good idling cooling performance, but it increases the load on the engine. To reduce the load on the engine and to have good idling cooling performance, generally a variable displacement compressor is used. The use of variable compressors

Verma, Nishith, Arumugam, Prabhakaran, Jha, Kaushal Kumar

Modeling of a Wedge Clutch in an Automatic Transmission

2010-01-018604/12/2010

A wedge clutch with a wedge ramp transfers the tangential force to an axial force. It has unique features of self-reinforcement and small actuation force, and can be packaged into tight spaces. This wedge clutch can be developed to apply to an automatic transmission (AT) or a hybrid transmission. This paper focuses on the simulation of one wedge clutch in AT during shifting. A mathematical formula is given to describe the self-reinforcement principle of the wedge. The dynamic model of a motor actuated wedge clutch during shifting is built to simulate and develop the control algorithm. The model is implemented in Matlab/Simulink, which includes a DC motor model, a dynamic model of the wedge mechanism and clutch pack, and a driveline model of AT which can simulate a gear shift process. The key characteristics such as variation of normal pressure, response time and energy consumption are evaluated, and the results show a favorable comparison with the traditional hydraulic clutch.

Yao, Jian, Chen, Li, Yin, Chengliang, Shu, Jie, Zheng, Xin, Lee, Chunhao, Dong, Yu, Kao, Chi-Kuan, Hebbale, Kumaraswamy, Samie, Farzad

Double Cone Friction Clutch

2009-01-293110/06/2009

In view of constantly increasing raw material cost and fuel prices it is a main target of truck manufacturers and fleet owners to save fuel. One pragmatic solution refers to switching on/off any auxiliary engine device on an “as needed basis”. The paper describes a new kind of friction clutch for engaging/disengaging an air compressor. Test results demonstrated more than 2 million cycles at full torque load. Prototype tests with a fully operational single cylinder air compressor have verified and proven the concept at realistic truck conditions. The authors will describe the development steps of the clutch and the planned development of the current concept.

Meichle, Stefan, Krafft, Rainer, Wolf, Andreas

Double Clutch Transmission (DCT) using Multiplexed Linear Actuation Technology and Dry Clutches for High Efficiency and Low Cost

2007-01-109604/16/2007

Stemming from predictions made for transmission adoption and sub-system volumes up to 2020 for the EU market, a concept study and recommendations are presented for a 6-speed 200Nm powershift transmission covering the following: Specific new features for low cost and high efficiency applied to a DCT, Novel, direct acting electromagnetic linear actuators for modulation of clutches and shift rails, Mechanical multiplexing to allow control of both clutches and shift rails using two linear actuators only.

Wheals, J. C., Turner, A., Ramsay, K., O'Neil, A., Bennett, J., Fang, Haiping

Development of Direct Electromagnetic Clutch System

2005-01-055104/11/2005

Honda has developed the SH-AWD(Super Handling-All Wheel Drive) system (Ref. 1), the world's first 4WD system capable of continuously and variably distributing torque to all four wheels of the vehicle. The use of this system enables torque to be employed in the control of the yawing moment and the application of control to equalize the load ratio between all the wheels of the vehicle. This results in higher turning stability and increased turning limit performance. These forms of control require a highly responsive actuator capable of controlling torque with a high degree of accuracy. A direct electromagnetic clutch in which solenoid attraction acts directly on the clutch was newly developed to satisfy the function described above. Detection of the solenoid air gap is required to enable high-accuracy control of solenoid attraction. A search-coil-type -sensor based on a new concept was developed and employed to enable detection of the solenoid gap.

Kunii, Rikiya, Iwazaki, Akihiro, Sekiya, Shigenobu, Kanno, Yutaka, Kitamura, Katsuhiro, Shibahata, Yasuji

Dana Torque Vectoring Differential Dynamic Trak™

2004-01-205305/04/2004

This paper presents a novel torque-vectoring (biasing) differential system Dynamic Trak™ that can be applied to both the inter-axle and the inter-wheel differential systems. The Dynamic Trak™ has three multi-plate clutches. The center clutch located inside the differential case provides a limited-slip or complete lock-up capability. The two outboard clutches positioned at either sides of the differential case selectively adjust the torque flow to the left or right shafts/wheels. An electronic control unit and a hydraulic circuit unit control the three clutches, realizing the active management of the torque to the two output shafts/wheels. The Dynamic Trak™ can provide maximum of 100% torque add or subtraction to the wheels, while maintaining the open differential feature. A virtual model representing a passenger car equipped with the Dynamic Trak™ has been developed. The simulation results show the handling and stability enhancements by the Dynamic Trak™.

Park, John, Kroppe, William J.

Engine Starting System Development by Belt Drive Mechanism

2002-01-108603/04/2002

The basic concept of the Toyota mild hybrid system is to provide a smooth and reliable engine restarting method from an idling stop, while at the same time being able to drive all of the accessories during the idling stop. This concept has been realized and marketed for the first time in the world, by utilizing a newly developed simulation of belt behavior to optimize the specification of the belt and its peripheral parts.

O-hori, Masae, Tanei, Katsutoshi, Yano, Yu-ichi, Hayama, Kenji, Sako, Shinji, Ezoe, Tomohiro

Creating Innovation in Torque Transfer Systems Through Optimization of Powder Metallurgy Components

2001-01-035003/05/2001

This paper will describe the BorgWarner Interactive Torque Management (ITM) system for FWD based AWD systems as well as the utilization of P/M technology for critical components within this system. The ITM is an electro-mechanical coupling device. The device consists of an electromagnet, ball ramp and wet clutch system. The system can be mounted anywhere in the drive line as well as integrated into components such as transfer cases and transaxles. The clutch actuation force is dependent on the current applied to the electromagnetic coil, providing a truly variable torque transfer device. The decision to make extensive use of P/M technology in the structural portion of this system was based on the net shape capability and weight reduction combined with the ability to chose from a wide range of engineered materials that resulted in the most economical total system package.

Weilbaker, Timothy R., Lumpkins, Earl R.

European Test Procedures and Test Equipment for Slip-Controlled Wet Disc Clutches

98225809/20/1998

With regard to the development and quality control of slip-controlled multi-disc clutches, different test procedures were previously used in Europe. These employed test procedures are presented and the requirements for future systems outlined. A new test bench concept is presented, which allows all the necessary procedures previously performed on separate test benches to be performed on a single test bench. This allows considerable time and money savings to be made during development and quality control of slip-controlled multi-disc clutches and transmission oils. Suppliers are presented with the opportunity to perform all the required tests themselves.

Frey, Dietmar, Ast, Ewald, Brügel, Edwin

Electronically Adaptive Transfer Case, Single Actuator Power Transfer System for Four Wheel Drive

97323411/17/1997

New Venture Gear developed an innovative torque transfer system that simplifies transfer case design. An external single actuator controls an automatic, dual-gear ratio transfer case. This single actuator design provides torque transfer to the front axle when it meets certain conditions. It makes shifting to a different gear ratio possible without the use of an additional actuator or mechanical lever.

Wilson, Robert J., Adler, Randy, Fox, Brad, Gasparek, Mike, Zamecnik, Nicole P.

Development of a New 4WD System: All-Mode 4WD

97068402/24/1997

This paper presents a new electronic torque split four-wheel-drive system called All-Mode 4WD, which has been adopted in the latest generation of sport-utility vehicles (SUVs). As a torque split system designed specifically for SUV use, it provides stable driving performance matching the driver's intentions under all sorts of operating conditions, from a completely natural on-road driving feel to powerful traction for off-road travel.

Takasaki, Toshiharu, Suzuki, Kunihiko, Murata, Shigeo, Hara, Tomoyuki, Nishio, Kouji

Ford Explorer Control Trac 4x4 System

95264511/01/1995

PURPOSE - Present the new Control Trac four wheel drive system which is the first application of an interactive four wheel drive in a sport utility vehicle. PROBLEM - The Control Trac system was developed in response to the need for a light weight, space efficient, customer friendly, and full function four wheel drive system. The system was targeted to be fully compatible with on highway and off road usage. CONCLUSION - The Control Trac system is a remarkably user friendly, practical, technologically advanced four wheel drive system; compatible with on highway and off road operation.

McKenzie, Clive A., Rama, Gordon P., Martins, Richard A.

Potential of Additional Mechanical Supercharging for Commercial Vehicle Engines

94226811/01/1994

Modern commercial vehicle engines are equipped with turbocharging and intercooling. This results in low emissions and fuel consumption. In the lower speed and load range and under transient conditions, these engines have disadvantages, as the fuel injection rate has to be limited to avoid excessive smoke emission. Also, the engine braking performance of highly charged, small displacement engines is also lower than that of large displacement engines. Mercedes-Benz decided to develop a combination of turbocharger and mechanical supercharger. In the lower speed range higher torque levels are possible and maximum torque is available without any lag especially in the transient mode with low smoke emission and fuel consumption. Vehicle performance during acceleration can be improved by up to 30%. During engine braking operation, the mechanical supercharger is activated throughout the whole engine speed range which results in a distinctive increase in braking power. Possible vehicle

Schmitz, Thomas N., Holloh, Klaus-D., Juergens, Rolf, Fleckenstein, Guenter

Vehicle Drawbar Test Characteristics of Electric and Viscous Clutch All Wheel Drive Systems

93305211/01/1993

Vehicle drawbar testing was conducted in order to establish the relative performance of all wheel drive electric and viscous clutch transfer case systems. The drawbar tests of a Ford Aerostar system with an electric clutch transfer case are compared to viscous clutch systems in a GM Astro and a Chrysler Grand Cherokee. The empirical test results and theoretical comparison show that the electric clutch transfer case system has a greater amount of torque transfer and its reaction time is faster.

Mid-Size Agricultural Tractors for Worldwide Markets

92168309/01/1992

Ford New Holland has developed a complete new line of agricultural tractors consisting of six models with modern styling and performance features and the necessary variants to satisfy worldwide markets. The key ingredients of the developmental program were Best in Class features in performance and fitness for use for improved reliability, durability, serviceability and safety to achieve industry leadership in overall customer satisfaction.

Endress, David K., Martenas, Wayne B., Siems, Gerald E.

Application of Phenolic for Air Conditioner Clutch Sheaves

89044502/01/1989

The use of low carbon steel is required for the design of electromagnetic clutches for automotive air conditioner (A/C) applications. This, coupled with the need for clutch cycling to improve vehicle gas consumption, will add to the noise level under the hood plus generate heat which reduces belt life. This new application of phenolic will improve upon the above problems and reduce cost, weight, and complexity.

Bekheet, Zaki, Palermo, Joseph C.

Finding New Sources Of Energy For Passenger Compartment Heating

09/01/1988

The evolution of the automobile engine is threatening to make it impossible, some day, to heat the passenger compartment properly. Current developments, especially improvements in efficiency, are reducing what the automotive engineer regards as a loss, but what constitutes for the heating engineer a resource with which to create a comfortable interior environment. Under these circumstances, maintaining proper heat levels requires complementary equipment.

Courbon, Guy

The “ECVT” Electro Continuously Variable Transmission

02/01/1988

With the popularization of easy driving in Japan, the quest to improve the fuel economy and vehicle performance of a small car with a torque converter automatic transmission (AT) has led to the development of the Electro Continuously Variable Transmission (ECVT). The Subaru ECVT which combines an electronically controlled magnetic powder clutch with the van Doorne's steel belt drive system employs a couple of conventional synchromeshes as a means of forward/reverse change-over mechanism and simple hydraulic control valves. This combination has realized smoothness and quick response of CVT operation and provides a compact size for the CVT with the weight of 45.4 kg. Fuel economy of Subaru Justy ECVT car with the one liter engine is thus improved by 15 to 20 % in Japanese 10-mode test cycle and at the 60 km/H constant speed respectively in comparison with that of three speeds torque converter AT. The description of the transmission and its control strategy including the powder clutch are

Sakai, Yasuhito

Torsional Dampers and Alternative Systems to Reduce Driveline Vibrations

87039302/01/1987

Fuel saving means vehicle operation at low engine speed and accordingly high engine torque. For that, recent engines have been tallored, developing up to 85% of the max, torque at 1.000 rpm. However, when applying this driving mode, the driver may be irritated by rattling noise and body humming. This is due to the fact that all drivelines have a natural frequency between 1.000 and 2.000 rpm, which cannot be displaced below 1.000 rpm by means of tuning of conventional torsion dampers. Diesel engines and more and more gasoline engines require an idling noise isolation stage. This stage adds to the total lash in the driveline and contributes to clonk and load reversal reactions. This paper describes various systems suitable to overcome these concerns.

Drexl, Hans Jürgen

High Efficiency Supercharger Increases Engine Output, Reduces Fuel Consumption Through Computer Control

86139210/01/1986

Efficiency of a supercharger mainly depends on the clearances between the rotors and the housing, but it has hitherto proved impossible to reduce the clearances without a strong possibility of seizure. A two lobe Roots type supercharger has been developed which overcomes this problem by means of a special resin coating on the rotors. As a result, an increase of 18% in volumetric efficiency of the supercharger is achieved. Engine torque is increased by 30%. Drive power loss resulting from the operation of a supercharger at partial load when boost was not required caused fuel consumption to increase by about 10%. An electro magnetic clutch and an air by-pass valve controlled by the onboard computer were used in the new supercharger to eliminate this fuel economy loss. A passenger car equipped with the new supercharged 2-liter engine demonstrated about the same acceleration performance as a 3-liter class car without sacrificing fuel economy.

Kato, Shinichi, Nakamura, Norihiko, Kato, Kichiro, Ohnaka, Hidemi

An Experimental Study of the Electromagnetic Clutch for the Automotive Air Conditioning Compressor

86058702/01/1986

Various physical conditions of the friction surfaces were studied to increase the breakaway torque of the electromagnetic clutch for the automotive air conditioning compressor. The conventional ground steel-ground-steel combination had a disadvantage of low breakaway torque in the running-in period of engagement cycles. This situation was greatly improved by using the combination of the ground armature plate and the machined rotor with zinc plating. In this new technique, the pitch and depth of the machining mark relative to the plating thickness was found to be important. Combinations of machined armature plates and the machined rotors, with or without zinc plating, were also promising, and the mechanism of friction with these surface combinations were analyzed.

Koitabashi, Takatoshi, Hiraga, Masaharu

Low Cost Electronic Vehicle Starting Device

84030702/01/1984

A two pedal drive device has been developped, using a standard dry clutch, an electric motor as an actuator and a microprocessor control. With the help of a compensator spring, a low power, low inertia motor with a fast response can be used. The control characteristic is basically a centrifugal law, with several modifications. Several sensors input information into the microprocessor and compensate for manufacturing tolerances and lining wear. The Electronic Clutch Control has been fitted to different cars and has given optimal results. It can be used in conjunction with manual transmissions, CVTs or other types of transmissions.

Filderman, René, Gruenberg, Pierre

Dual Cylinder Rolling Piston Rotary Compressor for Automotive Air Conditioner

83053902/01/1983

Recentry, conventional compressors for automotive air conditioner have been rapidly replaced with rotary type compressor, because rotary compressors satisfy the requirements such as compact size, light weight, high compression efficiency, high durability and so on. Especially, rolling piston type rotary compressor have many excellent characteristics, (Its feature and performance were described at 1981 SAE International Congress.) We successfully developed dual cylinder rolling piston type rotary compressor for automotive air conditioner. This new product has special model which enables to control capacity range. This paper shows the configuration and experimental result of dual cylinder rolling piston type rotary compressor for automotive air conditioner.

Fujisaki, Shuuji, Kawamura, Motomu, Kawasaki, Katsuyuki, Kawaguchi, Susumu

High Speed Power Shifting Transmission for Gas Turbines

67072702/01/1967

A 300 hp, four speed, forward and reverse, power shifting test box has been designed, fabricated, and tested by the Eaton Yale & Towne Research Center at a rated input speed of 30,000 rpm. The concept incorporates a torque limiting clutch on the input shaft to limit inertia shock loads during shifting, and unique expanding sleeve clutches for changing gear ratios. Expanding clutch material and design were developed through extensive bench testing and computer investigation. A 30,000 rpm high pressure, controlled leakage rotating seal was developed for the input shaft. Limited experience with the vehicle installation is also discussed.

Fergle, Donald J.

Design and Application of Heavy - Duty Clutches

64003801/01/1964

The paper covers basic design factors, testing procedures, and application considerations for clutches used in motor trucks, farm tractors, construction equipment, and stationary power units. Clutches discussed include spring loaded dry, spring loaded wet, over-center dry, over-center wet, electromagnetic single plate dry, electro-magnetic multiple disc wet, and hydraulic multiple disc. Basic and theoretical aspects of clutch design are converted into practical information useful in designing and applying clutches of various types. Because the scope of the paper is broad, many formula derivations were omitted to permit presentation of as much practical material as possible.

Acceptance Standards for Magnetic Clutches as Applied to Automotive Type Refrigerant Compressors

61058101/01/1961

Control Systems

61058801/01/1961

FRICTION MATERIALS

54006901/01/1954

Magnetic-Fluid Control Devices

49022401/01/1949

AIRCRAFT ELECTRIC REMOTE CONTROLS

43005501/01/1943

OLSEN METHODS OF BALANCING

36001901/01/1936

Electric Telemeter and Valve-Spring Surge

29002201/01/1929

THE electric telemeter presents an excellent means for investigating the phenomenon of valve-spring surge. Basically, the telemeter is composed of two differentially connected stacks of thin carbon discs so arranged that, when the apparatus is subjected to strain, the pressure is increased on one stack and decreased on the other. Each stack forms one arm of a Wheatstone's bridge, and the resistances of the stacks vary with the pressure on them, thus slightly upsetting the balance of the bridge. If an oscillograph galvanometer-element be substituted for the usual bridging instrument, the arrangement will be found suitable for making photographic records. To study valve-spring surge, the telemeter is connected across the points of a stiff C-spring, one end of which is held against the valve-spring in such a way that vibrations of the spring are transferred to the C-spring and thence to the telemeter. This equipment has made it possible to identify the cause of valve-spring surge as a

DONKIN, W. T., CLARK, H. H.

Air-Meter for Engine Research

27003201/01/1927

ENGINE power is an expression that has a wide range of meaning. In its most fundamental sense, it is the capacity for doing work developed in the engine cylinders and is limited by the breathing capacity of the engine, that is, its rate of air consumption. The author describes a positive rotary-displacement measuring apparatus designed to overcome the objections often raised to the use of the customary type of air-meter in the induction system. The contribution describes a method for attaining greater accuracy or simplicity of operation evolved in the course of an investigation, and the method described is easily applicable by others who may have similar problems requiring solution.

HUEBOTTER, H. A.

INSTRUMENTS FOR AUTOMOTIVE RESEARCH

25002301/01/1925

Due to tremendous production schedules and rapid advancement, the automotive industry is characterized by its effort to learn the answers to engineering research-problems with utmost dispatch, but the procedure is not without attendant risks. Costly errors have resulted from experimental work improperly planned and executed, from conclusions too quickly drawn and from unjustified interpretation of observed indications. Cut-and-try procedure is resorted to in many instances after hastily applied research methods have failed and, often, the apparently longer course involving systematic research would, in fact, have been fruitful of more prompt and more satisfactory results at a lower net cost. As originally presented, the paper was accompanied by a demonstration of instruments and apparatus especially adapted to automotive-research problems. These exhibits included Bureau of Standards Apparatus for measuring fuel flow by volume Carbon pile telemeter Clearance volume indicator

WARNER, JOHN A C

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