MXPA00003064A - Intelligent braking system for materials handling vehicles - Google Patents

Abstract

A computer controlled braking system utilizes gross vehicle weight of a materials handling vehicle and maximum allowable vehicle speeds to calculate braking force in response to a service brake request. For vehicles equipped with a caster brake, the calculated braking force is proportionally distributed between a drive brake and the caster brake. The drive brake includes a mechanical brake and motor braking which is performed by a traction motor. The drive brake force is divided between the mechanical brake and the motor braking so that the motor provides as much braking as possible to reduce wear on the mechanical brake and also to conserve battery power. For vehicles equipped with a caster brake, the caster brake portion of the calculated braking force is determined as a programmable percentage of the total braking force and can differ based on travel direction. The caster brake portion is clipped and reverts to the drive brake if it is below a minimum;and, if the calculated caster brake force is greater than a maximum, the caster brake force in excess of the maximum is clipped and reverts to the drive brake. A maximum caster brake current can be set to accommodate different brake hardware. A user of the vehicle can select adjustments to the calculated drive brake force and, if provided, can also select independent adjustments to the calculated caster brake force. If the vehicle has not substantially stopped within a given period of time after having its speed reduced to a low speed, the mechanical drive brake is fully applied.

Description

INTELLIGENT BRAKING SYSTEM FOR VEHICLES HANDLING MATERIALS BACKGROUND OF THE INVENTION The present invention relates in general to vehicles handling materials and, more particularly, to methods and apparatus for braking such vehicles. Although the present invention is generally applicable to vehicles handling materials, it will be described herein with reference to reach trucks and forklift trucks for which it is particularly applicable and for which it is initially used. The braking of the forklift trucks can be carried out by the use of a mechanical brake, as described in the U.S. patent. No. 5,057,728, which is incorporated herein by reference, or by the use of dynamic braking characteristics of the electric traction motor, such as is described in US Pat. Do not. ,340,202, which is incorporated herein by reference. The brake shown in the '728 patent is a three-stage brake; that is, the brake is capable of providing three levels of braking force, depending on the braking requirements. Of course, mechanical brakes are subject to wear; therefore, to reduce wear, and since the regenerative braking using the traction motor retains the battery charge, it is desirable to use the electric motor as much as possible for the braking requirements. In a reach forklift truck, a single driving wheel, electrically and steerably driven, is mounted in one corner of the truck's power unit, and a steerable wheel is mounted in the other corner. For some trucks, the steerable wheel is also provided with a brake or with a tilt brake. Therefore, although braking with motor and mechanical braking of the driving wheel and, in some applications also the mechanical braking of the steerable wheel are known for vehicles handling materials, there is a present need to improve the methods and apparatuses which they operate and coordinate these braking systems for improved braking performance. Such improvements would better adapt the braking performance for the known operating conditions of travel direction and allowable travel speed / fork height which distributes the braking requirements between mechanical braking and regenerative braking associated with an addressable driving wheel, the use of regenerative braking as much as possible and brake coupling on the steerable wheel in a proportion suitable for braking on the steerable wheel. Preferably, the improved braking control can be controlled by computer and therefore can be easily adapted in the field and also allows a simplified manufacture of vehicles handling materials using the improved braking control.

BRIEF DESCRIPTION OF THE INVENTION This need is met by the invention of the present application wherein a computer controlled braking system uses the gross vehicle weight of a vehicle handling materials and the maximum permissible vehicle speeds to calculate the braking force for the vehicle. The maximum allowable speed is determined in the direction of travel of the vehicle: forward, that is, forks forward; and in reverse, that is, the forward power unit and the height of the forks that carry the load of the vehicle. For vehicles equipped with a tilt brake, the calculated braking force is distributed proportionally and programmably between a drive brake and the tilt brake. The drive brake includes a mechanical brake, which is used to brake the vehicle when moving and also to keep the vehicle when it is stopped, and motor braking which is done by a traction motor which drives the driving wheel. The drive brake force, either the total calculated braking force or the braked brake portion of the braking force calculated if a tilt brake is provided, is divided between the mechanical brake and the motor brake so that the Motor provides as much braking as possible to reduce wear on the mechanical brake and also to conserve battery power. For vehicles equipped with a tilt brake, the tilt brake portion of the calculated braking force is determined as a percentage or proportion of the total braking force. The percentage is programmable and can differ based on the direction of travel of the vehicle. The tilt brake portion is reduced to zero or cut or inverted to the drive brake if it is below a minimum tilt brake force. In a similar manner, if it is calculated that the tilt brake force is greater than a maximum tilt brake force, the tilt brake force that exceeds the maximum tilt brake force is cut off and reversed to the drive brake. A maximum tilt brake current can be set to accommodate different brake hardware. A user of a vehicle can select settings for the calculated drive brake force and, if provided, can also select settings independent of the calculated inclined brake force. According to one aspect of the present invention, there is provided a method for braking a vehicle handling material, comprising adjusting the gross vehicle weight for the vehicle, determining the maximum permissible speed for the vehicle, detecting a service brake request. and, upon receiving the service brake request, calculate the braking force for the vehicle in response to the gross vehicle weight and the maximum allowable speed. The braking force calculated later can be converted to braking control actions. The step of determining a maximum permissible speed for the vehicle handling materials can comprise the steps of determining the height of the vehicle material handling forks, and correlating a maximum permissible vehicle speed with the height of the forks handling materials. vehicle. The step of determining a maximum permissible speed for the vehicle handling materials can further comprise determining a direction of travel of the vehicle handling materials and correlating the maximum permissible vehicle speed with the direction of travel of the vehicle. The step of calculating the braking force may comprise the steps of adjusting the braking force for the vehicle handling materials, equaling it to the gross vehicle weight by multiplying by 0.03 times the maximum allowable speed for the vehicle handling materials, and solving the equation resulting. To optimize brake operation for particular floor conditions, the method may further comprise determining an adjustment setting of the user for the strength of the user, and adjusting the braking force with setting the user adjustment. Preferably, the material handling vehicle has a driving wheel that is driven by a traction motor and a mechanical brake associated with the driving wheel, and the braking force is then divided by two to determine a portion of the braking force that is It will be carried out by the mechanical brake and a portion of the braking force that is to be carried out by the operation of the traction motor. The step of determining a portion of the braking force to be carried out by the operation of the traction motor may comprise subtracting the braking force portion to be carried out by the mechanical brake and a roller resistor. of the vehicle from the braking force. Then, if the result of subtracting the braking force to be carried out by the mechanical brake and the vehicle's rotating braking force is less than zero, the portion of the braking force that is to be carried The operation of the traction motor is set to zero. If the vehicle has a tilt brake in addition to a drive brake, the method may further comprise determining a braking force tilt brake portion and a braking force driving brake portion. The step of determining an inclination brake portion of the braking force preferably comprises taking a percentage of the braking force as the braking portion of the braking force. The method may further comprise taking a first percentage of the braking force as the tilt brake portion for moving a vehicle in a first direction, and taking a second percentage of the braking force as the tilt brake portion for the displacement of a vehicle in a second direction opposite the first direction. The method may further comprise determining a user adjustment setting for the tilt brake portion, and adjusting the tilt brake portion according to the adjustment setting of the user. In addition, the method may comprise determining a user adjustment setting for the drive brake portion and adjusting the drive brake portion according to the adjustment setting of the user. Preferably, separate separate user settings are available for the tilt brake portion and the drive brake portion. For the operation of the tilt brake, a minimum drive brake force can be established with the drive brake portion compared to the minimum drive brake force and set to zero if the drive brake force is less than the drive brake force. Minimum drive brake force. Similarly, a maximum tilt brake force can be established with the tilt brake portion that is compared to the maximum tilt brake force and set to a maximum tilt brake force if the tilt brake force is greater that a maximum tilt brake force. The determination of the drive brake portion of the braking force may comprise subtracting the inclining brake portion of the braking force from the braking force. Typically, the tilt brake is electrical and the method further comprises setting a maximum tilt brake current and limiting the current to the tilt brake to a maximum tilt brake current. In this way, various tilt brake hardware can be adapted. To ensure vehicle stop, a timer is started when the vehicle's operating speed is within a given first speed, for example, 1.6 km / h (1 mile per hour), and at the expiration of the timer, if the operation exceeds a given second speed, the mechanical brake is fully applied. According to another aspect of the present invention, a braking system for a vehicle handling material comprises a computer programmed to: determine a maximum allowable speed for the material handling vehicle, and calculate the braking force for the vehicle in response to a gross vehicle weight and the maximum allowable speed. The gross weight of the vehicle is usually set on the computer; however, it can be changed if the truck is modified or changed or if necessary in some other way. The computer can be further programmed to determine the setting of user adjustment for the braking force, and adjust the braking force with setting the user's adjustment. Preferably, the material handling vehicle comprises a driving wheel that is driven by a traction motor, and a mechanical brake associated with the driving wheel, and the computer is further programmed to: determine a portion of the braking force to be performed by the mechanical brake and determines a portion of the braking force that is to be carried out by the operation of the traction motor. When the material handling vehicle further comprises a tilt brake, the computer is further programmed to determine a braking force tilt brake portion, and determines the drive brake portion of the braking force. The computer can be further programmed to determine a user adjustment setting for the braking force inclination brake portion, and adjust the braking force inclination brake portion with the setting adjustment of the user. Similarly, the computer can be further programmed to determine a user setting for the braking force drive brake portion, and to adjust the braking force drive brake portion with the adjustment setting of the user. Preferably, the computer is programmed to use separate and user-independent settings for the tilt brake portion and the drive brake portion. When the vehicle handling material has a driving wheel that is driven by a traction motor and a mechanical brake associated with the driving wheel, the computer can be additionally programmed to: determine a vehicle operating speed, start a timer when the speed of operation of the vehicle is below a given first speed, before the expiration of the timer, determine if the operating speed exceeds a given second speed, and fully apply the mechanical brake if the operating speed exceeds the second speed given to the expiration of the timer. Therefore, an object of the invention of the present application is to provide a computer control of braking force calculations and adjustments at the time a brake service request is received; providing braking force calculations based on the gross vehicle weight of a vehicle handling materials, and the maximum permissible speed of the vehicle in response to a request for brake service; and have different braking efforts based on the direction of travel in order to take advantage of difference in the dynamic distribution of the weight that is a function of the direction of travel and consequently be able to optimize the braking operation (stopping distance) for each direction of displacement; adjust the braking forces of individual wheels in order to optimize the operation of the brake for the particular floor condition; to provide adequate braking effort between the driving wheel and the brakes of the steerable wheels; and to control the braking effort according to the maximum allowable travel speed (which is a function of fork height and direction of travel) in order to improve the dynamic feel of the truck while braking. Other objects and advantages of the invention will be apparent from the following description, the accompanying drawings and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a perspective view of a reach forklift truck incorporating the braking methods and the apparatus of the present invention; Figure 2 is a side elevational view of the forklift of Figure 1; Figure 3 is a perspective view of a power unit of the truck of Figure 1, taken from a right rear part of the truck; Figure 4 is a simplified block diagram of the control circuit of the present invention; and Figure 5 is a flow diagram illustrating the operation of the braking methods and the apparatus of the present invention.

DETAILED DESCRIPTION OF THE INVENTION Figures 1-3 show a forklift truck 10 that includes a power unit 15 which includes an operator compartment 20, a battery compartment 30 and a motor compartment 40. A battery 35, see Figure 2, in the battery compartment 30, supplies power to the traction motor 42 which is located in the engine compartment 40 and is connected to an addressable drive wheel 50 in the left rear corner of the unit. 15 of power and hydraulic motors (not shown) which supply power to the different systems inside the truck 10. Attached to the engine 42 is a brake 44 and a tachometer 46. A steerable wheel 55 is mounted in the right rear corner of the 15 power unit. A conventional steerable wheel brake 55a is provided in some trucks, see Figure 4. A pair of projections 60 support the forward end of the truck 10. An addressable steering lever 100 is mounted in the operator's compartment 20 to control the steering of travel of the truck 10 and a control handle 110 for controlling the speed of travel and the forward and reverse direction of the truck 10 as well as a fork lift, a fork extension and a fork inclination and side shift. A pole assembly 70, mounted on the front of the power unit 15 of the truck 10, includes a top guard 75. A pair of forks 80 are placed on a fork support mechanism 85, which is transported on the extendable pole elements 90. The fork support mechanism 85 may include a reach mechanism 92 to allow the forks 80 to extend forwardly of the pole assembly 70, a side shift mechanism to allow the forks 80 to move from side to side in relation to each other. to the pole assembly 70, and a tilting mechanism to allow the forks 80 to be inclined relative to the horizontal. As described in the US patent. 5,586,620, which is incorporated herein by reference, a scope mechanism 92 is attached to the pole assembly 70 extending by means of an assembly 94. A hydraulic cylinder (not shown) is operated by the control handle 110 to control the height of the forks 80. As shown in Figure 2, assembly 94 is raised. The height of the forks 80 is measured by a digital encoder, represented by the number 190, which may be similar to the device shown in FIG. the EU patent 5,103,226, which is incorporated herein by reference. The forks 80 can be tilted through a range shown by the arrows 96, by means of a hydraulic cylinder 200 which is located between the forks 80 and the fork support 85. The weight of the load on the forks 80 is measured by a pressure transducer 210 which is attached to a hydraulic line connected to the cylinder 200. Within the operator's compartment 20, depending on the truck model, an assembly 120 may also be located. of seat which is attached to the right side of the power unit 15, as shown. When installed, the seat assembly 120 includes a back support 125, a seat 130 and a shelf 135. The seat assembly is vertically adjustable for operator comfort. A armrest 140 is also supported in the seat assembly 120 for movement therewith. On the floor of the operator's compartment 20 are two pedals 150 and 155. The left foot pedal 150 operates an electrical switch to control the braking of the truck 10, while the right foot pedal 155 operates a switch that indicates the presence of the foot of the truck. operator on it. Also located within the operator's compartment are three additional pedals: a pedal 160 which corresponds to the pedal 150. A pedal 165 which corresponds to the pedal 155, and a pedal 170 which is an additional brake pedal. The operator must have one foot on, and press the pedal 150 or 160 in order that the truck 10 moves; otherwise, the truck's brakes are fully applied. The operator must also press any pedal, 155 or 165, in order to move the truck 10, if it is stopped. If the truck 10 moves, the removal of the foot from the pedals 155 or 165 will cause the truck 10 to idle. The switches controlled by the pedals 155 and 165 are switches known as "presence" or "cut back". The pedal 170 is an auxiliary brake switch. At any time when the operator presses the pedal 170, the brakes of the truck 10 will be applied immediately. An operator console 180 provides the operator with information regarding the status of the battery voltage and can provide additional information including indications regarding the height of the fork and the weight of the load on the forks 80. The simplified block diagram of figure 4 shows various components used in connection with the present invention which are associated with a microprocessor 300 contained in a primary control module, which is referred to as the access module 3, of an electronic control system for the truck 10. The truck 10 includes two braking modes. In the first mode, commonly referred to as the "interlocking" movement of the handle 10 in the opposite direction to the current direction of travel is recognized as an interlocking request and results in braking by the action of the traction motor 42. In the second mode, commonly known as a braking service, the operator removes the foot from the pedals 150 or 160, or presses the pedal 170. The methods and apparatus of the present invention perform braking service in response to a service request. brake which results in a combination of regenerative braking performed by the traction motor 42 and the mechanical braking performed by the brake 44, and if a tilt brake is provided on the truck, by the tilt brake. of brake service, the invention of the present application controls the braking of the truck 10 to improve the braking operation of the truck when calculating the braking force to be applied using the gross vehicle weight (GV) and the speed of maximum permissible displacement, which depends on the direction of travel of the truck 10 and the height of the forks, at the moment when the application is received. e brake service. The allocation of braking effort between the mechanical brake, ie the brake 44 for the driving wheel 10, and the regenerative braking of the traction motor 42 is optimized to reduce wear on the mechanical brake consistent with the motor capacity 42 to provide the necessary braking torque. In those trucks equipped with a tilt brake on the steerable wheel 55, the allocation of braking effort between the drive brake and the tilt brake is also made based on the weight distribution and the friction coefficients of the driving tire and the adjustable tire The braking service operations of the invention of the present application, which are performed under the control of the microprocessor 300, will now be described with reference to figure 5. When a brake service request is detected due to the operation of one of brake pedals 150, 160 or 170, the total brake force is calculated based on the requirements of the American National Standards Institute (ANSI): Total brake force = (3 x V x GVW) / 100 where GVW is the weight of the vehicle, in pounds and V is the maximum permissible speed for the vehicle. For the present invention, the GVW used includes the total unloaded weight of the vehicle and the maximum rated load weight for the vehicle, i.e., GVW is the total allowable fully loaded weight for the vehicle. And V, is the maximum permissible speed, in miles per hour (MPH) for the fully loaded vehicle. For example, for two forklift forklift truck models of the RR5000 series of forklift trucks manufactured by Crown Equipment Corporation, one that has a 107 cm (42") power unit, and one that has a power unit 122 cm (48") wide, the maximum permissible speed V is determined by the following table based on the direction of travel of the truck and the height of the fork: Maximum speed of the vehicle, in km / h (miles per hour) where "FF" means forks forward, "PUF" means forward power unit, free lift refers to a stowed or collapsed height of the mast of the truck, and CBH refers to a height limit above which The maximum permissible speed of the truck is reduced to a tow speed of 2.4 km / h (1.5 miles per hour). The total braking force is separated or divided between the driving tire and the steerable tire based on the known weight distribution and the coefficient of friction of the tire. Since the 107 cm (42") power unit has no tilt brake, 100% of the braking is done by the driving tire, the braking force of the driving tire or the driving braking force is further divided by braking. Regenerative motor and brake 44 of the three-stage friction brake in a motor armature shaft 42. The regenerative braking portion of the motor is made as large as possible, up to the limit for practical torque-to-torque output regeneration The remaining braking portion is performed by the three-stage brake 44. The braking force of the driving wheel and the braking force of the steerable wheel can each be adjusted to optimize the stopping distance for a particular floor condition. The adjustments are made by the user through a service menu screen on operator console 180 or other input device to microprocessor 300. Accordingly, when a request for braking service is received by the microprocessor 300 from the switches associated with one of the pedals 150, 160 or 170 for use in the traction / brake control, see blocks 220, 222 of figure 5, the Total braking force (TBF), see block 224, using the equation: TBF = GVW X .03 x V where GVW or the gross vehicle weight is set equal to a permissible fully loaded vehicle weight and V is the maximum allowable vehicle speed obtained, for example, from the previous table by using fork height and steering displacement of the truck.

By using the GVW of the truck to calculate the total braking force, all trucks with the same allowable speed will effectively produce the same stopping force "g" regardless of the truck's heights so that the heights will stop at approximately the same distance if they are traveling at the same speed and will have the same "sensation" of stopping when the braking service is performed. The use of the gross vehicle weight to calculate the total braking force also makes it easier to produce several trucks since the brakes do not need to be adjusted based on the weight of the vehicles, as in the past, but they will have braking force appropriate due to the calculation of the braking force constituting an aspect of the invention of the present application. After the total braking force is calculated, the inclination distribution of the total braking force, that is, the braking force which is to be provided by the tilt brake of the truck, is determined, see block 226. Of course, if brake is not provided inclination on the truck, as in the case of the 107 cm (42") wide truck, the entire braking force is applied by the brake 44 of the driving wheel The tilt distribution can be programmed on the microprocessor 300 and it can be adjusted to different values based on whether the truck is moving in the forward direction (PERF), that is, with the forks 80 forward, or in the reverse direction (PERR), that is, with the power forward 15. In a working mode of the invention of the present application, a default 25% incline braking portion setting (PERF = PERR = 25%) is used, due to the weight distribution of the 10 wheelbarrow, c on a default brake portion used for the forward and reverse directions of travel. However, any adjustment of the appropriate tilt brake portion can be made as desired or as advertised as necessary for particular truck or operating conditions. Due to variations in floor conditions and braking hardware, provisions are made to adjust the braking forces to optimize the braking conditions for a given application. For tilt braking settings, the user's operation settings allow the user to adjust the applied tilt brake force when the forks are below the free lift. Therefore, the user selects a multiplier which is used to modify the tilt brake force. The multiplier may vary from less than one to more than one with a series of nine incremental percentages ranging from about 62% to about 127% used in a work mode of the present invention. Therefore, the operator can select the tilt brake modification (CSET) settings from 1 to 9 to optimize tilt braking for floor or other operating conditions. You can also adjust the maximum tilt brake value (CSTMAX) to accommodate differences in the brake hardware. If a tilt brake value is selected that is greater than the maximum tilt brake value, the tilt brake value is set to the maximum tilt brake value with the rest of the requested brake value "trimmed" and transferred back to the brake of the driving wheel to maintain the total brake force calculated before. A minimum tilt brake value (CSTMIN) is also set, and if a tilt brake value is requested that is less than the minimum allowable tilt brake value, the tilt brake value is set to zero with the trimmed amount transferred back from the tilt brake. return to the driving wheel brake to maintain the total brake force as calculated before. The tilt brake will not be applied in the same way if the forks are raised above the maximum height of the tilt height (HT). For example, you can set the tilt height to the limit height or other height as required for a given truck. In summary, an initial tilt brake force (CST1) is calculated by taking the percentage of tilt brake (PERC) of the total braking force. It is noted that different percentages of tilt brake can be used for forward travel (PERC = PERF) and for reverse travel (PERC = PERR) of the truck: CSTl = TBF x PERC Then, any adjustment by the user is made by multiplying CST1 by user adjustment (CSET) to obtain a modified or adjusted tilt brake force (CST2): CST2 = CST1 x CSET The height of the fork is then compared to the tilt height and, if it is greater than the tilt height (HT), a final tilt braking force (CSET3) is set to zero: CST3 = 0 The final tilt brake force (CST3) is also set to zero if CST2 is less than a minimum permissible tilt brake value (CSTMIN). If these cases are not applied, then CST2 is tested to see if it exceeds the maximum tilt brake force (CSTMAX) and if so, CST3 is set equal to the maximum tilt brake force: CST3 = CSTMAX If none of these instances is applied, then CST3 is set equal to CST2: CST3 = CST2 Once the force to be applied to the tilt brake CST3 has been determined, the tilt brake current (CSTAMP) or the current to be applied to the tilt brake must be determined. The tilt brake current depends on the hardware of the tilt brake and can be calculated by the microprocessor 300; however, in a working mode of the invention of the present application, an inclination brake search table is used. For a specific tilt brake used in the 122 cm (48") truck, the following search table applies: CSTAMP CST3 (Current) (Force) The tilt brake current (CSTAMP) is determined by using the required tilt brake force (CST3) to enter the table and then interpolate it within the table. For example, you can compare the tilt brake force (CST3) with the table forces until the reading of the table force is greater than CST3, that is, if a tilt force of 363 kg is required ( 800 pounds), an initial entry into the table is made at a force of 370 kg (815 pounds) (i = 8) which is greater than the required 363 kg (800 pounds). The interpolation is then performed by subtracting the force at i - 1 from the required force (363 - 342 kg (800 - 755)) and dividing the result by the force by i - 1 (370 - 342 kg (815 - 755)) to obtain an interpolation fraction which is multiplied by the current difference of input i of the table to input i - 1 of the table to obtain an interpolation current. The interpolation current is then added to the current tilt value at input i-1 to obtain the required tilt braking current (CSTAMP). To accommodate the differences in tilt brake hardware, a current maximum tilt value (CST_MAXAMP) can be set so that the current to the tilt brake never passes over the maximum tilt current value. If CST3 is greater than the highest tilt brake force in the table, the tilt brake current is then adjusted to the maximum tilt current value: CSTAMP = CST_MAXAMP Once the determination of the inclination distribution for the braking service has been completed, the distribution of the drive side for service braking is determined, see block 228. The brake force distribution of the drive side (BF) is determined by subtracting the. braking tilt distribution of the total braking force (TBF) calculated before and when backing up any adjustments that can be made due to tilt braking limitations. More particularly, the initial inclination brake force is subtracted (CST1) of the total braking force (TBF) to find the original percentage of the total braking force to be provided by the drive-side brake. Adjustments to the braking force of the original percentage drive side are calculated by subtracting the final tilt brake force (CSET3) from the adjusted tilt brake force (CST2) and the result is driven to the braking force of the side Original percentage impeller to obtain the brake force of the drive side (BF). As with the tilt brake force, due to variations in floor conditions and brake hardware, provisions are made to adjust the drive brake force to optimize the braking conditions for a given application. For impulse brake settings, the user makes adjustments that allow the user to adjust the applied drive brake force when the forks are below free lift. Therefore, the user selects the multiplier which is used to modify the drive brake force. The multiplier may vary from less than 1 to more than one with a series of nine incremental percentages ranging from about 62% to about 127% used in a work mode of the present invention. Therefore, the operator can select drive brake modification (DSET) settings from 1 to 9 to optimize drive braking for the floor or other operating conditions: BF = [(TBF - CST1) + (CST2 - CST3)] x DSET Once the brake force of the drive side is finally determined, it must be distributed between the motor 42 and the mechanical brake 44 with the motor 42 providing as much braking force as possible. In order to ensure that the calculated braking forces do not exceed the capacity of the braking devices, limits are established on the calculated braking forces. The maximum braking force that a mechanical brake 44 can provide is defined as the maximum braking stop (PBMAX) and the maximum motor regeneration braking force is defined as (SEMAX). The rotational resistance (RR) of the truck is also taken into consideration when calculating the brake force of the drive side with the resistance to rotation on the truck defined by: RR = GVW x 0.016 where GVW again is the gross weight of the vehicle which is set equal to the weight of the fully loaded fully allowable vehicle. The motor and friction or mechanical braking forces are found by first determining the minimum step brake level (STEPBK) (1/2, 2/3 or 3/3) necessary to maintain the motor force to exceed its limit ( SEMAX), see block 230. Therefore: yes (BF - (SEMAX + RR)) > (2/3 then STEPBK = 3/3, otherwise if (BF - (SEMAX + RR))> (1/3 then STEPBK = 2/3; otherwise, STEPBK = 1/3.

Then, the torque setting point of the motor is determined by subtracting the calculated slow brake force (STEPBK_FR) and the turning distance (RR) of the driving force brake force (BF) and converting it into the moment of torque in the motor 42, see block 232.

MOTOR = (BF - STEPBK_FR-RR) [if MOTOR < 0 adjust MOTOR = 0] where STEPBK_FR = 0.132 x GVW x 1/3, 2/3 or 3/3.

BRAKE T = MOTOR X TORQUE_CONVERSION_CONST where TORQUE_CONVERSION_CONST is a constant which converts the braking force in the tire to torque in an engine for a given vehicle, and the calculation of this constant is well known to those skilled in the art.

For example, this constant for the RR5000 series for forklift trucks manufactured by Crown Equipment Corporation is calculated equal to 0.04315. Having determined the tilt and drive brake forces, the brakes are applied, see block 234. The braking force applied is maintained until the brake service request is complete, see block 236, at which time control of the brake is applied. traction / brake within the microprocessor 300 once again awaits the next request for brake service, see block 220. Since the torque of regeneration of the engine begins to decay at speeds less than 1.6 km / h (1 mile per hour), the mechanical friction brake 44 (and the tilt brake, if provided), is required to bring the truck 10 to a full stop and hold it, for example, when stopped. The service braking is applied, the mechanical friction brake 44 or the gradual brake can be applied in any of its three braking stages (1/3, 2/3 or 3/3) where 3/3 is the stage of braking required to keep truck 10 on a 15 degree gradient. If the truck brakes on a slope and the brake stage has been applied to a level less than 3/3, the truck may not be able to stop completely without additional braking from the brake 44. Consequently, additional time is provided for Fully apply the brake stage to 3/3 in the case where the truck does not come to a complete stop within a given period of time. After the braking service is applied as described above, a timer (TBRAMP_COUNT) is started when the truck speed falls below a given speed (BRFLIP_SPEED), eg 1.6 km / h (1 mile per hour) ). If the current speed of the truck is greater than a programmable speed (BRAKE_ZEROSPEED), for example 0 km / h (0 miles per hour), after TBRAMP_COUNT has elapsed, for example at 2 seconds, the brake 44 is applied in all its Stage value 3/3. Having described the invention of the present application in detail and with reference to the preferred embodiments thereof, it will be apparent that modifications and variations are possible without departing from the scope of the invention defined in the appended claims.

Claims (29)

1. A method for braking a vehicle handling materials, comprising the steps of: establishing the gross vehicle weight for the material handling vehicle, the gross vehicle weight comprises the total weight of the vehicle without load and the maximum rated load weight for the vehicle that handles materials; determine a maximum allowable speed for the vehicle handling materials; detect a request for brake service; and upon receiving the brake service request, calculate the braking force for the vehicle in response to the gross vehicle weight and the maximum allowable speed.

2. A method for braking a vehicle handling materials, as described in claim 1, further comprising the step of converting the braking force into braking control actions.

3. A method for braking a vehicle handling materials, as described in claim 1, wherein the step of determining a maximum allowable speed for the vehicle handling materials comprises the steps of: determining a height of forks handling vehicle materials; and correlating the maximum permissible speed of the vehicle with the height of the forks that handles vehicle materials.

4. A method for braking a vehicle handling materials, as described in claim 3, wherein the step of determining the maximum allowable speed for the vehicle handling materials further comprises the steps of: determining a direction of travel of the vehicle driving materials; and correlating the maximum permissible speed of the vehicle with the direction of travel of the vehicle.

5. A method for braking a vehicle handling materials, as described in claim 1, wherein the step of calculating the braking force upon receipt of the brake service request comprises the steps of: establishing a braking force for the vehicle that handles materials equal to the gross weight of the vehicle multiplied by 0.03 times the maximum permissible speed for the vehicle handling materials; and solve the resulting equation.

6. A method for braking a vehicle handling materials, as described in claim 1, further comprising the steps of: determining an established user setting for the braking force; and adjust the braking force with setting the user adjustment.

7. A method for braking a vehicle handling materials, as described in claim 2, wherein the vehicle handling material has a driving wheel that is driven by a traction motor, and a mechanical brake associated with the driving wheel, the The step of converting the braking force into braking control actions comprises the steps of: determining a portion of braking force to be performed by the mechanical brake; and determining a portion of the braking force that is to be realized by the operation of the traction motor.

8. A method for braking a vehicle handling materials, as described in claim 7, wherein the step of determining a portion of the braking force to be carried out by the operation of the traction motor comprises the step of subtract the portion of braking force to be carried out by the mechanical brake and a resistance to rotated the vehicle from the braking force.

9. A method for braking a vehicle handling materials, as described in claim 8, further comprising the step of establishing the function of the braking force to be carried out by operation of the traction motor to zero if the result of the subtraction of the braking force to be carried out by the mechanical brake and the rotational resistance of the vehicle from the braking force is less than zero.

10. A method for braking a vehicle handling materials, as described in claim 2, wherein the vehicle has a drive brake and a tilt brake, and the step of converting the braking force into braking control actions comprises the steps of: determining a brake portion of the braking force inclination; and determining a driving brake portion of the braking force.

11. A method for braking a vehicle handling materials, as described in claim 10, wherein the step of determining the braking force inclination brake portion comprises the step of taking a percentage of the braking force as a Tilt brake portion of the braking force.

12. A method for braking a vehicle handling materials, as described in claim 11, further comprising the steps of: taking a first percentage of the braking force as the tilt brake portion for moving the vehicle in a first direction; and taking a second percentage of the braking force of the tilt brake portion for moving the vehicle in a second direction opposite the first direction.

13. A method for braking a vehicle handling materials, as described in claim 10, further comprising the steps of: determining the adjustment setting of the user for the tilt brake portion; and adjust the tilt brake portion with the setting adjustment of the user.

14. A method for braking a vehicle handling materials, as described in claim 13, further comprising the steps of: determining a user adjustment establishment for a drive brake portion, and adjusting the drive brake portion with the establishment of user adjustment.

15. A method for braking a vehicle handling materials, as described in claim 10, further comprising the steps of: determining a user adjustment establishment for a drive brake portion, and adjusting the drive brake portion with the establishment of user adjustment.

16. A method for braking a vehicle handling materials, as described in claim 10, further comprising the steps of: establishing a minimum tilt brake force, - comparing the tilt brake portion with the minimum tilt brake force , - and set the zero-tilt brake force, if the tilt brake force is less than the minimum tilt brake force.

17. A method for braking a vehicle handling materials, as described in claim 10, further comprising the steps of: establishing a maximum tilt brake force, - comparing the tilt brake portion with the maximum tilt brake force , - and set the tilt brake force with the maximum tilt brake force if the tilt brake force is greater than the maximum tilt brake force.

18. A method for braking a vehicle handling materials, as described in claim 10, wherein the step of determining a driving brake portion of the braking force comprises the step of subtracting the force inclining brake portion. of braking force.

19. A method for braking a vehicle handling materials, as described in claim 10, wherein the tilt brake is electric, and the method further comprises the steps of: establishing a maximum tilt brake current, - and limiting the current to the tilt brake to the maximum tilt brake current.

20. A method for braking a vehicle handling materials, as described in claim 7, further comprising the steps of: determining a vehicle operating speed, - setting a timer when the operating speed of the vehicle is below a vehicle speed. first given speed; before the expiration of the timer, determine if the speed of operation exceeds a given second speed, - and fully apply the mechanical brake if the operating speed exceeds the second speed given before the expiration of the timer.

21. A braking system for a vehicle handling materials, comprising: a computer programmed to: determine a maximum permissible speed for the material handling vehicle, and - calculate the braking force for the vehicle in response to the gross vehicle weight and the maximum allowable speed, the gross weight of the vehicle comprises the weight of the total vehicle discharged and the maximum nominal load weight for the vehicle handling materials.

22. A braking system for a vehicle handling materials, as described in claim 21, in which the gross weight of the vehicle is established in the computer.

23. A braking system for a vehicle handling materials, as described in claim 21, wherein the computer is further programmed to: determine a user adjustment setting for the braking force; and adjust the braking force with setting the user adjustment.

24. A braking system for a vehicle handling materials, as described in claim 21, wherein the vehicle handling material further comprises a driving wheel that is driven by a traction motor, and a mechanical brake associated with the driving wheel , and the computer is further programmed to: determine a portion of the braking force that is to be carried out by the mechanical brake; and determining a portion of the braking force that is to be carried out by the operation of the traction motor.

25. A braking system for a vehicle handling materials, as described in claim 21, wherein the vehicle handling materials further comprises a drive brake and a tilt brake, and the computer is further programmed to: determine a portion Brake tilt braking force, - and determine a portion of brake drive the braking force.

26. A braking system for a vehicle handling materials, as described in claim 25, wherein the computer is further programmed to: determine the user adjustment setting for a braking force inclination brake portion, - and adjusting the tilt brake portion of the braking force with the setting of the user adjustment for the tilt brake portion.

27. A braking system for a vehicle handling materials, as described in claim 26, wherein the computer is further programmed to: determine the user adjustment setting for a brake portion of the braking force, - and adjusting the drive brake portion of the braking force with the setting of user adjustment for the drive brake portion.

28. A braking system for a vehicle handling materials, as described in claim 25, wherein the computer is additionally programmed to: determine the user adjustment setting for a brake portion of the braking force; and adjusting the drive brake portion of the braking force with the user setting setting for the drive brake portion.

29. A braking system for a vehicle handling materials, as described in claim 21, wherein the vehicle handling vehicle has a driving wheel that is driven by a traction motor, and a mechanical brake associated with the driving wheel, the computer is also programmed to: determine the speed of operation of the vehicle, - start a timer when the speed of operation of the vehicle is below a given first speed, - before the expiration of the timer, determine if the operating speed exceeds a second given speed, - and fully apply the mechanical brake if the operating speed exceeds the second speed given before the expiration of the timer.