Showing papers on "Slip ratio published in 1988"

Method and apparatus for controlling shoe slip of crawler vehicle

Abstract: This invention relates to a method and apparatus for controlling shoe slip of a crawler vehicle directed to automatically prevent an endless track from slipping beyond the state where maximum pulling force is attained thereby liberating an operator from troublesome operations requiring a high level of skill The shoe slip control method is accomplished by switching the operation mode to a predetermined engine output mode when a shoe slip ratio exceeds a predetermined value during the operation of the vehicle The apparatus includes an acceleration detecting device (27) for detecting the acceleration in the travelling direction of the vehicle, a travelling speed computing circuit (31) for the endless track, an actual vehicle speed computing circuit (32) for calculating the actual vehicle speed on the basis of the acceleration thus detected, a shoe slip ratio computing circuit (33) for calculating the shoe slip ratio from the actual vehicle speed and the track travelling speed, and an engine output control circuit for switching the engine output mode on the basis of the shoe slip ratio thus calculated

Influence of wall slip on extrudate swell: a boundary element investigation

Abstract: This paper reports a numerical study of the extrudate swell by a transient Boundary Element Method (BEM). Furthermore the fluid, which is modeled by a differential constitutive equation, is allowed to slip at the wall, where the slip velocity is a prescribed function of the wall shear stress. This function is a curve fit of the extensive data of Ramamurthy on linear low density polyethylene which incorporates two parameters: a critical wall shear stress above which slip occurs, and another parameter which governs the shape of the slip velocity versus shear stress curve. The results show that wall slip reduces both the amount of extrudate swell and the critical Weissenberg number above which our numerical scheme no longer converges.

Modeling of Extrusion With Slip Boundary Conditions

Abstract: Slip at boundaries is possible in viscous flows; for instance, in the extrusion of foodstuffs, water-containing materials, and some polymers. There are two phenomenological descriptions of slip: The first is based on the presence of a very thin, low viscosity boundary layer and has been derived for capillary flow and extrusion; the second is based on a Coulomb-friction mechanism and has been derived for capillary flow only. After a survey of these results, the friction model is derived for the extrusion process. All calculations are as simple as possible: two-dimensional, Newtonian, isothermal, and with constant boundary layer parameters of coefficients of friction. A strong dependence of pumping characteristics and efficiency on the slip boundary conditions, and also on the extruder length in the case of friction, was found, especially when slip is only allowed for at the screw surface. Exercises like these may help in understanding abnormal extrusion behavior of slippery materials in practice.

The effects of slip velocity at a membrane surface on blood flow in the microcirculation.

Abstract: Closed-form solutions are presented for blood flow in the microcirculation by taking into account the influence of slip velocity at the membrane surface. In this study, the convective inertia force is neglected in comparison with that of blood viscosity on the basis of the smallness of the Reynolds number of the flow in microcirculation. The permeability property of the blood vessel is based on the well known Starling's hypothesis [11]. The effects of slip coefficient on the velocity and pressure fields are clearly depicted.

System method for drive force distributing control for front-and-rear-wheel drive motor vehicle

Abstract: A system for controlling distribution of drive forces from a drive source unit to front and rear wheels of a four-wheel drive motor vehicle includes drive force distributing means for transmitting the drive forces to the front and rear wheels at a continuously variable distribution ratio, first speed detecting means for detecting a rotational speed (Nf) of the front wheels, second speed detecting means for detecting a rotational speed (Nr) of the rear wheels, and control means for calculating a slip ratio (S) of the rear wheels to a road on which the motor vehicle is running based on the rotational speeds (Nf, Nr) of the front and rear wheels, calculating a distribution ratio between the drive forces to be distributed to the front and rear wheels based on the slip ratio (S), and controlling the drive force distributing means to transmit the drive forces from the drive source unit to the front and rear wheels according to the distribution ratio. According to a method of controlling distribution of drive forces to the front and rear wheels, a continuously variable optimum distribution ratio is determined in view of a slip ratio between the wheels and the road, and the drive forces from the drive source unit are distributed and transmitted to the front and rear wheels according to the distribution ratio.

Dispersion in Presence of Slip and Chemical Reactions in Porous-Wall Tube Flow

Abstract: This paper deals with the problem of studying the effect of tangential velocity slip on the concentration profiles of a solute which is convectively diffusing and simultaneously undergoing irreversible, first order homogeneous and heterogeneous chemical reactions in a porous wall tube, under isothermal laminar flow conditions. It is shown that the presence of velocity slip at the porous wall induces an increase in the concentration of solute across the entirecross-section of the tube while an increase in the rates of chemical reactions is found to reduce the concentration under both slip and no-slip boundary conditions. Accurate eigen values, eigen functions and the concentration profiles are determined for the cases when slip or no-slip boundary condition holds at the wall.

Anti-lock braking system for a vehicle having a traction control module

Abstract: A vehicle anti-lock braking system having a master cylinder operated upon operation of a brake operating member, a wheel cylinder activated by a pressure produced by the master cylinder, and an anti-lock control device which includes a slip ratio detector for detecting a slip ratio of a drive wheel of the vehicle, and a pressure regulating device for controlling a pressure in the wheel cylinder, so as to maintain the slip ratio in an optimum range. The system also has a traction control device including a traction control power source, and a communication switching device for selective communication of the pressure regulating device with the traction control power source or the master cylinder. The switching device maintains a discharge port of the pressure regulating device in communication with a reservoir while the traction control power source is in communication with the pressure regulating device, and disconnects the discharge port from the reservoir while the master cylinder is in communication with the pressure regulating device.

Drive force distribution control system for four-wheel drive motor vehicle

Abstract: A drive force distribution control system in a four-wheel drive motor vehicle for distributing drive forces from an engine (11) of the motor vehicle to first and second wheels (17FL,17FR;17RL,I7RR] of the motor vehicle includes drive force distribut ing means (14) for distributing and transmitting the drive forces to the first and second wheels, first speed detecting means (20F) for detecting a rotational speed (Nf) of the first wheel, second speed detecting means (20R) for detecting a rotational speed (Nr) of the second wheel, torque detecting means (21) for detecting a torque (Tr) transmitted to the second wheel, and control means (22) for controlling the drive force distributing means. The control means calculates a slip ratio (S) of the second wheel to a road on which the motor vehicle is running based on the rotational speeds of the first and sec­ond wheels, calculates a ratio (Tr/S) between the torque (Tr) and the slip ratio (S), determines a distribution ratio between the drive forces to be distributed to the first and second wheels based on the ratio between the torque and the slip ratio, and controls the drive force distributing means to distribute and transmit the drive forces to the first and second wheels according to the dis­tribution ratio.

Traffic performance of a bulldozer running on a weak terrain

Abstract: To clarify the trafficability and the traffic performance of a bulldozer operating on a weak terrain at driving and braking state, several vehicle tests were executed on a remolded silty loam terrain of 30% water content by use of a small tracked vehicle of 3.55kN weight, 71cm contact length and 20cm width of track belt. From the measured relations between driving and braking force, drawbar-pull and effective braking force, sinkage and slip ratio, it is clarified that the largest drawbar-pull is obtained at 3.2 grouser pitch height ratio and the locomotion resistance increases with the increment of slip ratio at driving state, and the sinkage under the rear sprocket at driving state is larger than that at braking state due to the large amount of slippage and the large eccentricity.

Method for detecting slip ratio and method for adjusting belt tension of accessory driving belt

Abstract: PURPOSE: To suppress the generation of the abnormal sound of a belt by calculating the rate of no-tension term of a loose side belt form the dynamic variation value of belt tension, comparing this with a reference rate, and detecting the slip ratio of the belt. CONSTITUTION: A belt tensioner 32 is externally provide don the loose side belt 8a of an accessory driving belt 8. The tensioner 32 consists of a tension roller 32a and an actuator 32b. A driving signal is outputted to this actuator 32b from a control unit 33 to control the operation of the tensioner 32. An engine rotation signal and an accessory load signal are inputted into the control unit 33 to calculate the rate of no-tension term of belt tension and this rate of no-tension term is compared with a reference rate to detect a slip ratio. When the rate of no-tension term exceeds the reference rate, a control signal is outputted to the actuator 32b and the tension roller 32a is projectingly driven, thereby increasing belt tension to lower a slip ratio. COPYRIGHT: (C)1989,JPO&Japio

Slip preventing device for driving wheel

Abstract: PURPOSE: To improve the start accelerating property by detecting the friction coefficient between a tire and the road surface and the slip ratio during deceleration, estimating and storing the road surface condition based on the detection values, and controlling the driving torque in response to the road surface condition stored at the time of restart. CONSTITUTION: The slip ratio is detected by a slip ratio detecting means 14 based on the rotating speed of a driving wheel 11 detected by a wheel speed sensor 12 and the vehicle acceleration detected by an acceleration sensor 13, the road surface condition is calculated by a road surface condition calculating means 15 based on this slip ratio and the vehicle acceleration. This road surface condition is stored in a memory means 16 as a numerical value. At the time of restart after the vehicle is stopped, the driving force is calculated by a driving force control means 17 based on the road surface condition immediately before the stop. An actuator 18 is driven according to this calculation result, one of a throttle valve, a transmission, an ignition coil and an injector is controlled, the torque of the driving wheel is reduced, and the occurrence of a slip is suppressed. COPYRIGHT: (C)1989,JPO&Japio

Power torque variable divider for four-wheel drive vehicle

Abstract: PURPOSE:To make accelerability corresponding to a driver's intention and optimum fuel consumption securable, by judging the driver's intention on the basis of the operated variable of an accelerator pedal, and adjusting each power distribution ratio to both front and rear wheels. CONSTITUTION:A variable torque transfer 2 consists of wet multiple disc clutches 5 and 6 set up each among a drive shaft 4, a front wheel shaft 4a and a rear wheel shaft 4b and selector valves 9 and 10 installed in a hydraulic circuit connecting a hydraulic pump 7 or a reservoir 8. The variable torque transfer 2 controls these selector valves 9 and 10 according to the four-wheel torque transferring ratio derived from an accelerator operated variable and a slip ratio by an electronic control unit 3 whereby it distributes and transmits power to the front wheel shaft 4a and the rear wheel shaft 4b at the proper ratio.

Driving force controller for motor vehicle

Abstract: PURPOSE: To enable suppression of slippage of right and left wheels at any timing, by obtaining a driving force correcting signal by calculation based on a slip ratio obtained from a vehicle speed signal and a rotation speed signal. CONSTITUTION: A slip detecting means 20 operates the slip ratio of driven wheels based on a vehicle speed signal fed from a vehicle speed sensor 11 and a rotation speed signal fed from a rotation speed sensor 12 and produces a driving force correction signal. A motor control amount operating means 30 operates a control amount signal based on a load signal fed from a load sensor 13, an accelerator angle signal fed from an accelerator angle sensor 14 and a driving force correction signal fed from a slip detecting means 20. Motor controllers 41, 42 for a driving means 40 regulate the electric power to be fed to motors 51, 52 for driving respective driven wheels 61, 62 based on the control amount signal. COPYRIGHT: (C)1989,JPO&Japio

Manufacture of seamless pipe

Abstract: PURPOSE:To prevent problems of biting and passing-through of a rolled stock to suppress the flaws on a inner surface and to improve the rolling efficiency by measuring the biting time and the passing-through of the rolled stock time to obtain both slip ratios based on the measured values, comparing with a reference slip ratio and controlling a set value of rolling for the next material to make the difference to be zero. CONSTITUTION:As to signals of a load cell 43, the time from a rise time to a reach time reaching a load value of a load level setting derive 51 for the rolling is denoted as the biting time t1 and stored in an arithmetic and storage device 54. More, from the reaching time of the output of the load cell to the load value of the rolling load level setting device 51 to the time of departing the rolling material from the rolls is denoted as the passing-through time t2 to store in the same device 54. Then, the biting time t1 and the passing-through time t2 are given to an arithmetic and control device 55 to calculate the slip rate at biting and passing-through time. After that, comparing with the slip rate capable of boring by a reference setting device 58, the next roll setting value is controlled when both slip rates are under the reference value, the difference between the slip rate and the reference slip rate is to become zero, and when the both sides or one side of the slip rates are over the reference value, the difference between the higher slip rate and reference value is to become zero.

Vehicle driving force control device

Abstract: PURPOSE:To prevent a sudden change in an engine driving force by selecting the optimum control characteristic map in accordance with a slip ratio while giving priority to and selecting a defined control characteristic map when an engine is unloaded or when traveling backward. CONSTITUTION:A map selecting means (g) selects the optimum control characteristic map in accordance with a slip ratio calculated by an operating means (c) based on a driving wheel speed (a) and a body speed (b), from a map setting means (f) in which plural control characteristic maps are stored. However, when an engine is not loaded or when traveling backward, a defined control characteristic map is selected prior to regular map selection, a setting means (h) obtains a target throttle opening value in accordance with an accelerator operating quantity (d), and a control means (j) controls a throttle actuator (i) based on the target throttle opening and an actual throttle opening (e). Thereby, a sudden change in an engine driving force can be prevented when shifting from an unloaded condition to a loaded condition at the time of traveling, while being fixed to a defined map at the time of traveling backward, without giving a sense of incompatibility of operating accelerator to a driver.

Shoe slip control method and apparatus therefor for caterpillar r vehicle

Abstract: This invention relates to a shoe slip control method and apparatus therefor which is directed to automatically prevent in advance a track from excessively slipping beyond the state where the maximum pulling force is attained, and to liberate an operator from a troublesome operation requiring a high level of skill. The shoe slip control method can be accomplished by switching the operation mode to a predetermined engine output mode when a shoe slip ratio exceeds a predetermined value during the operation of the caterpillar R vehicle. The apparatus includes acceleration detection means (27) for detecting the acceleration in the travelling direction of the vehicle, a track travelling speed calculation circuit (31), an actual vehicle speed calculation circuit (32) for calculating the actual vehicle speed on the basis of the acceleration thus detected, a shoe slip ratio calculation circuit (33) for calculating the shoe slip ratio from the actual vehicle speed and the track travelling speed, and an engine output control circuit for switching the engine output mode on the basis of the shoe slip ratio thus calculated.

Method for anti-lock control

Abstract: PURPOSE:To enhance control characteristics for a slip mu road by allowing the difference between the fluctuation in speed between a right and a left rear wheel applied by a predetermined correction factor varying between '0' and '1' based on car speeds and the higher speed out of the right and left rear wheel speeds, to be the second difference in speed. CONSTITUTION:The output from wheel speed sensors 6FL through 6RR goes to operating circuits 9 through 12 so as to be operated. As a correction factor K becomes a value close to '0' in the low speed running zone, the second difference in speed obtained by a subtraction circuit 21 becomes a value close to VH (high select speed out of the right and left rear wheel speeds). Braking distance can be thereby shortened for the low speed running zone in a slip muroad. In addition, as the correction factor K becomes a value close to '1' in the high speed running zone, the second difference in speed becomes a value close to VH- V=VL (low select speed out of the right and left rear wheel speeds). The slip ratio of the rear wheel at the low mu side of the slip mu road becomes therefore small, thereby enabling directional stability to be enhanced.

Controller for blade of bulldozer

Abstract: PURPOSE:To raise the efficiency of excavating and pushing operations by preventing slip of bulldozer blade by a method in which horizontal and vertical components of excavation resistance are detected and the ratio of both components is compared with a given set value to control the inclination of blade. CONSTITUTION:For obtaining horizontal resistance Rh and vertical resistance Rv, turning angle sensors 10 and 11, a load sensor 12, and an oil pressure sensor 13 are provided. By a CPU 20, the driving of an oil-pressure controller 30 is controlled on the basis of calculated resistances Rh and Rv. The oil pressure to be supplied to a tilt cylinder 4 is controlled to control the pitch angle of the blade 3. Actual tracting force can thus be increased, slip ratio can be lessened, and the wearing of crawler belt by unnecessary slip can be prevented.

Four-wheel-drive vehicle

Abstract: PURPOSE:To avoid a tight corner braking phenomenon by transmitting power to one of the front and rear wheels of an FF four wheel drive vehicle via a one-way clutch and controlling a transfer gear ratio being related to the tire slip ratio at the time of tight cornering. CONSTITUTION:In an FF four-wheel-drive vehicle, the power of an engine 1 is directly transmitted to front wheels 5 via a clutch and a transmission 2, a front wheel differential gear 3, and front wheel axles 4. The front wheel differential gear 3 is also power transmittingly connected to two sets of one way clutches 11, 12 via the pairs of gears 7 and 8 of a transfer device 6 and a direction changing gear 10, to transmit the rotation of a propeller shaft 13 to rear wheels 16 via a rear wheel differential gear 14 and rear wheel axles 15. The gear ratios of the pairs of gears 7 and 8 are set above '1', '1 + S' ( S = a slip ratio at the time of tight cornering) respectively, and each of the pairs of gears 7, 8 are switched over go as to use the pair of gears 7 at the time of direct-connected four wheel driving by means of a sleeve 9 while using the pair of gears 8 at the time of normal traveling.

Clutch control method

Abstract: PURPOSE:To make a fixed travel 'feeling' possible without relation to the load condition of a vehicle by controlling the slip ratio of a clutch changing in response to the load condition of the vehicle according to a variation slip ratio at the time of making a fork-life truck start CONSTITUTION:A CPU 18, when it decides that a car speed responding to the stepping-on amount of an accelerating pedal 14 is more than a predetermined speed, controls an actuator 6 through an interface 9 and an actuator-drive-circuit 19 in order to put a clutch 2 to the state of semi-clutching When a fork-lift truck is stated under a load condition, its load manifests itself as the slip of the clutch 2 The CPU 18 decides this by a difference between a real slip ratio and a standard slip ratio, that is, a variation slip ratio And, the CPU 18 calculates the regulating quantity of the stroke of a rod 6a according to the variation slip ratio, and controls the actuator 6 through an actuator-drive-circuit 20 And, when a vehicle which has started in the state of semi-clutching reaches the predetermined speed, the clutch 2 is made to be in the state of complete contact

Direct connection/slip changeover control method for variable speed slipping clutch

Abstract: PURPOSE:To eliminate the stick/slip phenomenon of a clutch plate and prevent the generation of torsional vibration of a driving system by making slipping control, while avoiding the use in a range of low slip ratio, of a slipping clutch for driving a water feed pump, etc. CONSTITUTION:When the discharge pressure of a water feed pump 3 is lowered, a rotation command signal 24 from a PID controller 23 starts to increase, increasing a current which is fed to the solenoid 28 of a rotating speed control valve 27. Accordingly, a clutch operating pressure is increased and the slip ratio of a slipping clutch 2 is reduced, increasing the discharge pressure of the pump 3. The rotation command signal 24 is always compared with a 5-% set signal 35 corresponding to the 5-% slip ratio of the clutch 2 and an 8-% set signal 37 corresponding to its 8-% slip ratio by a comparator 33. And, when the signal 24 is increased above the signal 35, a switchover signal 38 is outputted from the comparator 33 and given to a solenoid 41 and the signal 24 is switched over to a direct connecting signal 44 and outputted to the solenoid 28. This maximum value signal is received by the control valve 27 to keep the direct connecting condition of the clutch 2.