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Showing papers on "Slip ratio published in 1987"


Patent
27 May 1987
TL;DR: In this paper, an antiskid control device comprising detectors for measuring circumferential velocities of a plurality of wheels is presented, consisting of an actuator for operating braking oil pressure for each wheel and an electric circuit for calculating friction coefficients on the road surfaces to which the wheels are in contact.
Abstract: In an antiskid control device comprising detectors for measuring circumferential velocities of a plurality of wheels an actuator for operating a braking oil pressure for each of the wheels and an electric circuit for calculating friction coefficients on the road surfaces, to which the wheels are in contact, calculating aimed wheel circumferential velocities from the friction coefficients on the road surfaces and operating the actuator such that each of the aimed wheel circumferential velocities and each of the measured wheel circumferential velocities coincide with each other, the electrical circuit operates the actuator by setting individual aimed wheel circumferential velocities for the plurality of wheels from a vehicle deceleration calculated from an average value for the friction coefficients on the road surfaces with which a plurality of wheels are in contact, respectively, and the slip ratio for each of the plurality of wheels

55 citations


Journal ArticleDOI
TL;DR: In this paper, the authors deal with frictional heating, pore pressure rise, and migration of fluid, and speculates upon their consequences for triggering of earthquakes and emission of earthquake light.
Abstract: Summary. Accurate estimation of frictional stress is crucial to determining the bounds of pre- and post-earthquake states of stress. A long-term average value of 10 MPa, deduced from heat flow data in the San Andreas fault zone, is frequently cited, but it may or may not represent the resistive stress of an individual slip event. Based on 1-D modelling, this paper deals with frictional heating, pore pressure rise, and migration of fluid, and speculates upon their consequences for triggering of earthquakes and emission of earthquake light. Analytic solutions are obtained for temperature and pore pressure rises due to frictional heating. Results are obtained for three heating models: 1, instantaneous heating; 11, constant heating rate; and 111, heating rate proportional to inverse square root of time. For the same total heat generation and physical parameters, solutions indicate that, for times less than twice the slip duration or distances with two thermal diffusion distances, temperature and pressure distributions are sensitive to heating models; at greater times and distances, they are insensitive to models. Though temperature rise due to I-m slip under 10MPa frictional stress may reach 200K or more on the slip surface, the rise is not measurable in practice at a distance beyond about 10 m from the slip surface. Estimates of pore pressure rise (0.2-2MPa) depends crucially upon permeability and slip duration. Darcy flow may exceed lO-'m s-' at one thermal diffusion distance; and immediately after the slip ends, reverse flow towards slip surface develops. Because the pore pressure front can advance beyond the temperature front by 100-1000 times, measurement of pore pressure variation is an alternative to temperature measurement for estimating frictional stress. A rise of 500Pa is measurable at 330m within 30 days for a fault slip with frictional heat production of 10MJm-2. It is speculated that the propagating pressure front created by an initial slip, rather than the fluid flow itself, may weaken the frictional strength elsewhere and lead to additional minor slips and perhaps a larger earthquake. With large frictional stress and displacement, heating may also

51 citations


Patent
23 Dec 1987
TL;DR: In this paper, a control value of the control apparatus for controlling a device or devices loaded on a vehicle, for example, a slip ratio against a road surface of driven wheels for a slip control apparatus (traction control apparatus) is determined as a final control value based on plural input signals.
Abstract: A control value of the control apparatus for controlling a device or devices loaded on a vehicle, for example, a slip ratio against a road surface of driven wheels for a slip control apparatus (traction control apparatus) is determined as a final control value based on plural input signals. For every input signal, plural control zones corresponding to its signal value are present. For every combination of the control zones, a basic control value is memorized in a memory; an adaptability for the control zone corresponding to each signal value is determined as a first adaptability; a second adaptability is determined on the basis of the first adaptability obtained for every input signal; and an inference control value is then determined on the basis of the second adaptability and the basic control value. From the numbers of inference control values and second adaptabilities corresponding to the number of all combinations of the control zones, there is determined the final control value.

29 citations


Patent
16 Nov 1987
TL;DR: In this article, a throttle valve control circuit calculates an actual slip ratio between a tire and road surface from drive wheel speed sensed by front wheel rotational frequency sensors 31, 32 and vehicle speed detected by a rear wheel rotor frequency sensor 30.
Abstract: PURPOSE: To prevent excessive slip restraint by releasing fuel supply from decrease control when the rotational frequency of an engine is shifted from acceleration to deceleration CONSTITUTION: A throttle valve control circuit 34 calculates an actual slip ratio between a tire and road surface from drive wheel speed sensed by front wheel rotational frequency sensors 31, 32 and vehicle speed sensed by a rear wheel rotational frequency sensor 30 When the actual slip ratio exceeds a predetermined set one, drive force reduction control including fuel supply reduction control is started by a fuel cut device 36 When the rotational frequency of an engine detected by an engine rotational frequency sensor 39 is shifted from acceleration to deceleration, fuel supply reduction control is released Thus, control releasing timing can be carried out early by monitoring the increase and decrease of engine rotational frequency, so that a responsive lag in a power train P between an engine 10 and drive wheels 16, 17 due to tortion or the like of a propeller shaft 12 can almost be eliminated COPYRIGHT: (C)1989,JPO&Japio

20 citations


Patent
02 Jul 1987
TL;DR: In this article, the wheel slip of the vehicle is monitored and if found to be in excess of an allowable limit or limits the control map currently in use is changed or downgraded to one which exhibits less rapid engine power generation characteristics.
Abstract: A plurality of control maps which are used to control the position of an engine throttle valve or similar device which effects the power output of the engine, are stored in memory. The wheel slip of the vehicle is monitored and if found to be in excess of an allowable limit or limits the control map currently in use is changed or downgraded to one which exhibits less rapid engine power generation characteristics. On the other hand, if the rate at which a control element such as an accelerator pedal is moved in direction which demands increased engine output is greater than zero; the amount of wheel slip is below the allowable limit or limits; and the control signal being produced by the instant control map is at its maximum permissible level for the instant position of the control element, then the currently used map is upgraded to one which permits increased and more rapid engine power development. Alternatively, it is possible to define upper and lower accelerator depression limits and use these in a manner that when the depression is below the lower limit map upgrading is inhibited while when above the limit upgrading is induced if the slip ratio remains at an acceptable level for a selected period of time.

19 citations


Journal ArticleDOI
TL;DR: In this article, the authors measured up to a minimum distance of 0.15 μm from the wall for tube flow of aqueous solutions of anionic polyacrylamides (Praestol from the Stockhausen Corporation, at a concentration c 0=0.25 percentage by weight).
Abstract: Velocity profiles were measured up to a minimum distance of 0.15 μm from the wall for tube flow of aqueous solutions of anionic Polyacrylamides (Praestol from the Stockhausen Corporation, at a concentration c0=0.25 percentage by weight). The profiles measured could be recalculated on the basis of the flow curve. Extrapolation of the profile to the wall resulted in finite velocity values (slip‐velocity vs). This slip phenomenon could not be calculated in advance on the basis of the flow curve alone. Within the range of wall shear stress τw examined, the dependence of vx on τw was linear for a given polymer concentration and exhibited no threshold. The slip velocity vs decreased if capillary active substances or strong electrolytes were added to the solution; divalent cations (Ca+ +) being ten times more effective than mono‐valent ones (Na+). The increment of flow velocity from v=0 to v=vs with increasing distance from the wall occurs within a fluid layer which borders the wall (or a layer of adsorbed macro...

18 citations


Patent
20 Apr 1987
TL;DR: In this article, the acceleration slip ratio of a driving wheel was calculated and sent to an engine ECU 14 to prevent acceleration slip by combining the actions of leaning mixture and delaying the ignition timing and resting some of cylinders.
Abstract: PURPOSE:To prevent acceleration slip by combining the actions of leaning mixture. delaying the ignition timing and resting some of cylinders by steps in accordance with the detected acceleration slip amount of a driving wheel to successively reduce the generated torque of an engine. CONSTITUTION:According to the detected signals from a driving when speed sensor 11 and a driven wheel speed sensor 12. the ECU 13 calculates the acceleration slip ratio S of a driving wheel and sends the calculated data to an engine ECU 14. Next, the ECU 14 controls the driving mode of injectors 1 to 4 to lean the fuel mixture until the received acceleration slip ratio S increases to S1. The ECU 14 then controls whose injectors 1 to 4 to lean the fuel mixture and the ignition timing regulating means 15 to delay the ignition timing during the period from the point of the acceleration slip ratio S in excess of S1 to the point that the ratio S reaches S2. In the next step, during the period from the point of the acceleration slip ratio S in excess of the S2 to the point that the ratio S reaches S3, the ECU 14 makes driving control of the injectors to interrupt both the mixture leaning and ignition timing delay in two cylinders and to lean the mixture in the rest two cylinders. When the ratio S exceeds the S3, the ECU 14 rests two cylinders and controls driving of the ignition timing regulating means 15 to delay the ignition timing and the injectors to lean mixture. Thus the engine output can be reduced by combining those steps.

11 citations


Journal ArticleDOI
Yih-o Tu1
01 Mar 1987
TL;DR: In this article, the slip near the solid/liquid/fluid contact line is described by a phenomenological model in which the slip coefficient is inversely proportional to the liquid film thickness.
Abstract: The slip near the solid/liquid/fluid contact line is described by a phenomenological model in which the slip coefficient is inversely proportional to the liquid film thickness. The proportionality constant is so small that there is practically no slip anywhere except near the contact line where the slip mechanism is adequately described. The evolution of the free surface and the slippage of the contact line can be computed. Results for the case of constant viscosity are presented. The slip rate at the contact line is given in terms of material parameters of density, viscosity, and the rotating speed of the disk as well as the empirical slip proportionality constant. Accordingly, the way to control the slippage of the contact line is clearly indicated.

7 citations


Patent
13 May 1987
TL;DR: In this paper, a car speed sensor is used as an input sensor for detecting the state of a car, and an inner/outer wheel discriminating sensor and right and left wheel revolution speed sensors are installed.
Abstract: PURPOSE:To maintain the drive transmission power of outer wheels onto the road surface in turn and the lateral force necessary for turn by controlling the differential limiting torque in the direction in which the actual outer-wheel slip ratio accords with an aimed outer-wheel slip ratio. CONSTITUTION:A differential means 3 for transmitting the engine driving power in distribution into the right and left driving shafts 1 and 2, permitting differential movement, is equipped with a differential limiting mechanism 4 for generating the differential limiting torque. A control means 6 increases and decreases the differential limiting torque on the basis of the signal of an input sensor 5 for detecting the state of a car. Further, a car speed sensor 501 as input sensor 5, inner/outer wheel discriminating sensor 502, and the right and left wheel revolution speed sensors 503 and 504 are installed. The control means 6 sets an aimed outer-wheel slip ratio which keeps the driving transmission power onto the road surface and the lateral force necessary for turn. The differential limiting torque is controlled in the direction in which the actual outer- wheel slip ratio detected by the input sensor 5 accords with the aimed outer- wheel slip ratio.

7 citations


Patent
19 Sep 1987
TL;DR: In this paper, a turning limit is made higher by controlling an increase or decrease in differential limiting force from the outside on the basis of detected signals of a turning direction and the rotary speed of right and left driving wheels, and prohibiting the function of a driving wheel propulsion control device.
Abstract: PURPOSE:To make higher a limit to turning radius by controlling an increase or a decrease in a differential limiting force from the outside on the basis of detected signals of a turning direction and the rotary speed of right and left driving wheels, and prohibiting the function of a driving wheel propulsion control device. CONSTITUTION:A control device 13 judges a turning direction on a steering angle 142. For example, when a vehicle turns to the left and a right wheel WR is faster than a left wheel WL, the device 13 judges a condition as in an initial turn and outputs a control current signal (i) to an electromagnetic proportion reducing valve 46 so as to reduce clutch pressure 'P' down to zero. After the intermediate time of turning and when the left wheel WL is faster than the right wheel WR, it is judged that an inner wheel spin is taking place and a driving force is being released from the left wheel WL, differential limiting torque 'T' is so increased or decreased as to make the slip ratio SR of the outer wheel WR agree to a predetermined slip ratio S0, and a work prohibiting signal (d0) is outputted to a traction control device 7 when said differential torque 'T' is being limited. According to the aforesaid constitution, a turning limit can be made higher.

6 citations


Journal ArticleDOI
TL;DR: In this paper, the angular momentum theory was used to predict the shaft power, which was derived from measurement of the slip factor, blockage factor, and leakage flow, and the difference between the calculated values and the experimental results on the shaft performance was 5 % for the range of φ less than 0.3 and 11 % for φ= 0.45.
Abstract: In this paper, prediction of the shaft power is studied. The slip factor and the leakage flow factor used for the performance calculation are obtained experimentaly. The method of prediction of the shaft power is based on the angular momentum theory, and it is derived from measurement of the slip factor, blockage factor and leakage flow. The slip factor is strongly related to the blade angle β2, the number of blades Z and the capacity coefficient φ, and it is smaller than 0.35 at 170 degree of β2, which is much smaller than that for the backward blades. The difference between the calculated values and the experimental results on the shaft power is 5 % for the range of φ less than 0.3 and is 11 % for φ= 0.45.

Patent
Kunitaka Furuya1, Koji Shibahata
20 Nov 1987
TL;DR: In this paper, the authors proposed a method to prevent oversteering of steer characteristics by a method wherein control is effected based on the slip ratio of a wheel so that when the slip ratios is high, a drive force distributed to front wheels is further increased.
Abstract: PURPOSE: To prevent oversteering of steer characteristics, by a method wherein control is effected based on the slip ratio of a wheel so that when the slip ratio is high, a drive force distributed to front wheels is further increased. CONSTITUTION: A front wheel rotation speed sensor 20F and a rear wheel rotation speed sensor 20R are formed with a well-known reed switch, and output respective pulse signals of a frequency proportioning the rotation speeds of front wheels 17F and rear wheels 17R. A control unit 22 is provided with a microcomputer, and processes output signals from the sensors 20F and 20R to control a pressure control valve. From the rotation speed sensors 20F and 20R, a slip ratio is determined, and control is effected so that when the slip ratio is high, a drive force distributed to the front wheels is further increased. COPYRIGHT: (C)1989,JPO&Japio

Patent
12 Oct 1987
TL;DR: In this paper, the authors proposed to obtain a maximum braking efficiency from keeping the slip ratio of wheels at a fixed value and preventing the wheel lock by causing the brake fluid pressure to be decreased if the wheel slip ratio is more than a fixed values with respect to a pseudo vehicle-running speed based on a wheel turning speed at the time of wheel braking.
Abstract: PURPOSE:To obtain a maximum braking efficiency from keeping the slip ratio of wheels at a fixed value and preventing the wheel lock by causing the brake fluid pressure to be decreased if the slip ratio of wheels is more than a fixed value with respect to a pseudo vehicle-running speed based on a wheel turning speed at the time of wheel braking CONSTITUTION:There is provided a deceleration reference value changing means which detects the maximum value of wheel acceleration by means of a wheel acceleration detecting circuit 5, and changes the deceleration reference value to be higher or lower according to the size of the value detected Therefore, when the maximum acceleration is small, that is, either the rotating inertia of a wheel 1 is large or the coefficient of friction with the road surface is small, even if the brake fluid pressure is decreased, a recovery delay in the wheel acceleration takes place Thereupon, when a pseudo vehicle-running speed deviates largely from an actual vehicle-running speed, the deceleration reference value is determined to be lower than that in the case where the maximum acceleration is large Consequently, the recovery delay in the wheel acceleration is compensated and the pseudo vehicle-running speed can be prevented from deviating downwards largely from the actual vehicle-running speed, and the control efficiency of such an inaccurate anti-skid control as the slip ratio of wheels becomes unreasonable can also be prevented from becoming worse

Patent
02 Oct 1987
TL;DR: In this article, a ring gear and a pulser PS are used to generate electric pulses at each pitch of teeth formed in the tooth part of the ring gear for accurate measurement of the slip ratio of a belt even when the rotation speed of a driving shaft is fluctuated.
Abstract: PURPOSE:To enable accurate measurement of the slip ratio of a belt even when the rotation speed of a driving shaft is fluctuated, by a method wherein a pulley on the diving or the driven side is adapted to generate a number of electric pulses per one full turn. CONSTITUTION:A ring gear RG, secured on a driving shaft SH1, and a pulser PS, generating one electric pulse at each pitch of teeth formed in the tooth part of the ring gear, are provided as a pulse generating means mounted on the shaft SH1, and a rotary encoder RE of the driven shaft SH2 generates one electric pulse at one full turn. The pulser PS shields light through rotation of the ring gear RG when the crest part of the tooth form passes, and causes light to pass when the root part thereof passes. Pulses, generated by the driving and driven shafts SH1 and SH2, are inputted to a processing circuit CP, and after the pulses are computed for processing, the results are displayed on digital gauges DM1, DM2, and DM3.

Patent
30 Jun 1987
TL;DR: In this paper, the authors proposed a method to improve the stability of a vehicle under braking and shorten the braking distance by calculating the target wheel peripheral speed based on a road friction coefficient and a wheel turning angle and controlling a wheel peripherals speed to approach this target speed.
Abstract: PURPOSE:To improve the stability of a vehicle under braking and shorten the braking distance by calculating the target wheel peripheral speed based on a road friction coefficient and a wheel turning angle and controlling a wheel peripheral speed to approach this target wheel peripheral speed. CONSTITUTION:When a brake pedal is depressed for braking, a dummy vehicle speed Vr1 is calculated by a setter 17 based on the output or the like of a wheel peripheral speed (Vw) detector 7 and a turning radius r1 is calculated by a setter 19 based on this Vr1 and the output or the like of a steering angle detector 21 respectively. Next, a target slip ratio Sr is calculated from Vr1, r1 and a friction coefficient mu1, and a target wheel peripheral speed Vs is calculated from this Sr. On the other hand, the ratio between the descending rate and ascending rate of the wheel peripheral acceleration/deceleration obtained by a differentiator 8 from this Vw is calculated by a computer 10, a friction coefficient mu2 corresponding to this ratio is calculated by a converter 15, then the target wheel peripheral speed Vs is calculated by the setter 12 based on this friction coefficient mu2.

Patent
09 Apr 1987
TL;DR: In this paper, the authors proposed a method to ensure a vehicle to be stopped in a minimum stopping distance by braking within the range in which the frictional coefficient between the ground and wheels is around at its maximum.
Abstract: PURPOSE:To assure a vehicle to be stopped in a minimum stopping distance by braking within the range in which the frictional coefficient between the ground and wheels is around at its maximum. CONSTITUTION:Slip ratio S of wheels can be calculated from an equation S=(V1-V2)/V1 according to the outputs from a wheel speed detector 6 and a ground speed detector 10. In the range in which the slip ratio S exceeds 1, the wheels are quickly locked. Thus, in order to brake in the range in which the slip ratio S is less than 1, the oil 1 pressure supplied to wheel cylinders 2 is gradually changed in increment of a predetermined constant value. It is determined according to outputs from drag sensors 8a-8d whether or not the drag is increased, and if it is increased, the oil pressure is increased by the constant value. If there is no increase in drag, the oil pressure is decreased by the constant value. This permits the drag to have a slip ratio of about 1.

Patent
08 Sep 1987
TL;DR: In this paper, a control unit 20 receives signals Vr, Vl, Vor, Vol from speed sensors 21-24 for detecting the speeds of wheels 2-5, and also receives a throttle opening degree signal TA, an engine rotational speed signal Ne, a gear position signal GP and accelerator signal Aa.
Abstract: PURPOSE:To maintain the running performance of a vehicle while eliminating a slip at one wheel, by delivering a control signal to a brake means, preferentially to the output control of an engine by a skid control means so that the one wheel is braked. CONSTITUTION:A control unit 20 receives signals Vr, Vl, Vor, Vol from speed sensors 21-24 for detecting the speeds of wheels 2-5, and also receives a throttle opening degree signal TA, an engine rotational speed signal Ne, a gear position signal GP and accelerator signal Aa. The unit 20 determines whether the vehicle is in a starting acceleration condition or a steady-state running condition, in accordance with the vehicle speed, and delivers a drive signal to an actuator 30 or 31 for left or right drive wheel 2, 3, which has a larger slip ratio than other, in order to brake it when when the difference between the slip rates of the left and right device wheels 2, 3 exceeds a predetermined value, thereby it is possible to make both slip rates equal to each other.

Patent
02 Jul 1987
TL;DR: In this article, the accuracy in a length from the top of a rolling stock was improved by measuring slip and grip ratios in an online mode using a detector for the stock top end and correcting calculated slip and ratio values.
Abstract: PURPOSE:To improve the accuracy in a length from the top of a rolled stock and to reduce variations in the plate width of the stock by measuring slip and grip ratios in an online mode using a detector for the stock top end and correcting calculated slip and grip ratio values. CONSTITUTION:Both the distance LM between a front stage horizontal rolling mill and a detector for the rolled stock top end and the distance LR between the top end bitten by the front rolling mill and the detector are calculated by equation I. A slip ratio ffor is given by equation II based on the distance LM and LR. The distance L3 which the rolled stock advances for a given period of time after the rolling stock is bitten by a back stage rolling mill is obtained by substituting the slip ratio ffor of equation II into f in equation I. A grip ratio fbac is obtained by equation III based on the L3 and the advancing distance L1 of the rolled stock obtained by equation I. The quality of rolled stocks is improved by conduct of the plate width control for a hot strip mill in a feedforward system using the corrected slip and grip ratios.

Patent
12 Aug 1987
TL;DR: In this article, a new speed governing method of an asynchronous motor to public is presented, which uses a microcomputer to control three sets of silicon control, each set has three, linking with 3-phase AC respectively.
Abstract: This invention discloses a new speed governing method of an asynchronous motor to public. Three-phase AC arranges in different sequence, resulting in three kinds of 3-phase forward sequence and three kinds of 3-phase backward sequence. The three combinations of forward sequence and backward sequence have a phase difference of 120 degrees. Various phase sequences are switched in certain cycles and rules, which makes the stator circular field generate advance or lag within certain frequency. The circulation of the stator circular field becomes faster or slower, and speed governing is achieved. The accomplishing method is to use a microcomputer to control three sets of silicon control, each set has three, linking with 3-phase AC respectively. This speed governing method is of high efficiency and has a feed back brake.

Journal ArticleDOI
TL;DR: In this paper, the authors investigated the cross-slip effect associated with the flow of a monatomic, slightly rarefied gas over a rough surface, assuming that the characteristic dimensions of the roughness are comparable with the molecular mean free path.
Abstract: The phenomenon of gas dynamic slip associated with the flow of a monatomic, slightly rarefied gas over a rough surface is investigated. It is assumed that the characteristic dimensions of the roughness are comparable with the molecular mean free path. It is shown that if there is anisotropy of the surface shape the relation between the slip velocity and the friction stress vector becomes tensorial. In this case for almost any orientation of the gas dynamic flow the so-called cross slip effect is observed. The symmetry of the slip coefficient matrix is proved for fairly general assumptions concerning the type of roughness, the law of reflection of molecules from the surface, and the law of intermolecular interaction. The components of the slip coefficient matrix are calculated by a variational method for a corrugated model of the roughness.

Patent
13 Jul 1987
TL;DR: In this article, a rotary encoder was used to detect a slip of a band saw blade by providing speed detecting means of a driving wheel and a driven wheel, a calculating means, a comparing means, an output means generating signals such as a warning.
Abstract: PURPOSE:To detect a slip of a blade highly accurately by providing speed detecting means of a driving wheel and a driven wheel, a slip ratio setting means of a band saw blade, a calculating means, a comparing means, an output means generating signals such as a warning. CONSTITUTION:A rotary encoder 11 is fixed to a driven wheel shaft 9 and connected to a cover 12 by an angle 13, and the rotating speed of a driven wheel 5 is detected as output pulses. Similar constitution is provided for a driving wheel 4. When a band saw blade 6 is stretched or the driving wheel 4 generates a slip due to excessive cutting, the frequency of pulse signals of the driven wheel 5 side is decreased than that of the driving side. If the slip ratio becomes a preset value or more, calculation is performed and a warning or a stop signal is generated. According to this device, a slip of the band saw blade 6 can be detected highly accurately.


Patent
09 Nov 1987
TL;DR: In this paper, the relation between the slip ratio of drive wheels to a road surface and the ratio of the driving force of a vehicle to the axle load received by the drive wheel on the basis of the friction coefficient of the road surface as a parameter was investigated.
Abstract: PURPOSE:To accurately discriminate the surface state of a running road, by preliminarily storing the relation between the slip ratio of drive wheels to a road surface and the ratio of the driving force of the driving apparatus of a vehicle to the axle load received by the drive wheel on the basis of the friction coefficient of the road surface as a parameter. CONSTITUTION:An ABS computer 37 operates the speed of drive wheels and a car speed on the basis of the signals inputted from rotation sensors 38 of front and rear wheels to input the same to a running road surface state discrimination apparatus 28 where the slip ratio of the drive wheels is operated. The discrimination apparatus 28 operates coefficient of driving force on the basis of the axle load inputted from an axle load sensor 40 and the driving force inputted from a driving force sensor 41. The relation between the slip ratio and the coefficient of driving force is compared with a driving force coefficient characteristic curve preliminarily calculated from the experiments on the surface of a dry concrete road and ice and stored to discriminate the degree of the friction coefficient of a road surface. The discrimination signal is inputted to a controller 25 for four-wheel steering to perform the variable control of a steering ratio characteristic.

Patent
20 Jun 1987
TL;DR: In this paper, a value of brake operation amount detected by a brake sensor and that of acceleration detected by an acceleration sensor are input to an electronic control unit (ECU) 40 in order to calculate the aimed acceleration on the basis of a specific pattern.
Abstract: PURPOSE:To stabilize control operation with the identical control pattern with no relation to the surface condition and to prevent any wheel lock by constantly making the ratio of brake operation amount to acceleration change correspond to 1:1, and providing slip ratio with its upper limit for making control. CONSTITUTION:A value of brake operation amount detected by a brake sensor 25 and that of acceleration detected by an acceleration sensor are input to an electronic control unit (ECU) 40 in order to calculate the aimed acceleration on the basis of a specific pattern. And, brake oil pressure of hydraulic brake devices 11 to 14 is controlled by the ECU 40 in order to make the acceleration detected value be the aimed value, and acceleration corresponding to brake operation amount is made to be identical with no relation to the surface condition. Also, valves detected by turning angle sensors 15, 16, 22 are input to the ECU 40 form making brake control by providing the upper limit of slip ratio calculated with regard to vehicle speed. Incongruous feeling of brake operation is dissolved for stabilization and a wheel is prevented from locking by the above structure.

Journal ArticleDOI
TL;DR: In this article, the drag on two equal spheres in rigid contact falling along their line of centres is calculated in the slip flow regime, and a useful interpolation formula is derived by means of a variational principle.
Abstract: The drag on two equal spheres in rigid contact falling along their line of centres is calculated in the slip flow regime. Standard viscous flow theory is employed with the necessary slip boundary conditions. The drag is seen to depend on the ratioλ=l/a wherel is the mean free path of an atom in the surrounding gas and ‘a’ is the radius of the sphere. Two exact limiting cases are obtained for the drag, viz: smallλ and largeλ, and a useful interpolation formula is derived by means of a variational principle. The equivalent sphere approximation is found to give satisfactory results.

Journal ArticleDOI
TL;DR: In this paper, the problem of the separation of Uranium isotopes from the fluid-dynamic point of view is considered, and the technique based on the separator nozzle effects is discussed.

Patent
12 Nov 1987
TL;DR: In this paper, the authors proposed a voltage frequency pattern (P3) in case of a high tractive force and a voltage V is higher than a usual V frequency pattern(P1) in a V/f area which takes a linear function value relative to a frequency f.
Abstract: PURPOSE:To increase am output torque as compared with a slip ratio and obtain a desired high output torque while controlling an increase of motor current by increasing a voltage in a V/f area. CONSTITUTION:A pattern(P3) is a voltage frequency pattern in case of a high tractive force and a voltage V is higher than a usual voltage frequency pattern(P1) in a V/f area which takes a linear function value relative to a frequency f. Therefore, an increase of output torque can be made larger than that of slip ratio and it is possible to obtain a high output torque while controlling an increase of motor current. Accordingly, a temperature rise can be prevented, an inverter control capacity can be reduced and an output torque can be increased.