Patent Application
20120049479
Vehicles, such as diesel-electric locomotives, may be configured with truck assemblies including two trucks per assembly, and three axles per truck, for example. The three axles may include at least one powered axle and at least one non-powered axle. The axles may be mounted to the truck via lift mechanisms, such as suspension assemblies including one or more springs, for adjusting a distribution of locomotive weight (including a locomotive body weight and a locomotive truck weight) between the axles.
As the vehicle travels along the rails, the amount of load on each of the axles of the truck can vary, with each axle also having a maximum load weight. In certain conditions, such as during inclement weather, proper traction with the track may be lost, thereby resulting in one or more wheels slipping. Accordingly, the tractive effort for these vehicles may be less than optimized. For example, the tractive effort may be affected on trains, particularly for heavy trains or hauls, during start-up, on inclines, and during adverse rail conditions, such as caused by inclement weather or other environmental conditions.
In known rail vehicle systems, the springs of the suspension systems for the trucks are preloaded. For example, each of the springs is preloaded based on a normal amount of weight to be supported by the suspension system for the axles. As a result, under certain conditions, the preloaded springs may not provide the sufficient normal force to maintain proper contact between the wheels of the truck and the track, especially during inclement or adverse rail conditions.
In accordance with various embodiments, systems and methods provide variable spring stiffness for weight management in a vehicle. One embodiment includes a plurality of springs and a plurality of spring retainers configured to adjust a number of inactive coils of the plurality of springs. Additionally, a motor is provided that is connected to the plurality of spring retainers and configured to actuate the spring retainers to adjust the number of inactive coils of the plurality of springs. Further, a controller is provided that is coupled to motor to control the motor to actuate the spring retainers to adjust the number of inactive coils of the plurality of springs.
The present invention will be better understood from reading the following description of non-limiting embodiments, with reference to the attached drawings, wherein below:
To the extent that the figures illustrate diagrams of the functional blocks of various embodiments, the functional blocks are not necessarily indicative of the division components. Thus, for example, one or more of the functional blocks may be implemented in a single piece of hardware or multiple pieces of hardware. It should be understood that the various embodiments are not limited to the arrangements and instrumentality shown in the drawings.
As used herein, an element or step recited in the singular and proceeded with the word “a” or “an” should be understood as not excluding plural of said elements or steps, unless such exclusion is explicitly stated. Furthermore, references to “one embodiment” of the present invention are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. Moreover, unless explicitly stated to the contrary, embodiments “comprising” or “having” an element or a plurality of elements having a particular property may include additional such elements not having that property.
It should be noted that although one or more embodiments may be described in connection with powered rail vehicle systems having locomotives with trailing passenger or cargo cars, the embodiments described herein are not limited to trains. In particular, one or more embodiments may be implemented in connection with different types of vehicles including wheeled vehicles, other rail vehicles, and track vehicles.
Example embodiments of one or more apparatus and methods for weight management of a vehicle are provided. The various embodiments provide dynamic weight management of a vehicle, which includes changing the load among the axles to redistribute the load on the axles of a truck in the vehicle system. As described below, one or more of these embodiments provide for dynamic weight management of a vehicle that transfers reaction forces among axles of the vehicle, for example, from a middle/center or inner axle to outer axles by varying the stiffness of one or more springs of a suspension system of the vehicle. For example, in some embodiments an arresting mechanism is used to change the number of active coils of the springs by arresting one or more (or a portion thereof) of the coils of the springs.
As used herein, when reference is made to arresting one or more coils, this generally refers to making the one or more coils of a spring inactive or ineffective. For example, arresting one or more coils includes locking or otherwise stopping movement or compression of one or more coils or a portion of the springs, such as by locking the one more coils in place.
By practicing the various embodiments and at least one technical effect is increased traction on the powered axles, which may facilitate the tractive effort during certain traction limited modes of operation. Moreover, by practicing the various embodiments, less traction motors may be used to generate the same amount of tractive force or effort. For example, on a six axle truck, traction motors may be provided on only four of the axles instead of all six axles. Additionally, weight transfer between axles in accordance with various embodiments provides improved contact and traction between the rail and the wheel, which allows the truck of the vehicle to haul heavier loads, such as hauling a load with less traction motors.
While one embodiment of the presently described subject matter is set forth in terms of a powered rail vehicle, alternatively the subject matter may be used with other type of vehicles as described herein. The rail vehicle 100 includes a lead powered unit 102 coupled with several trailing units 104 that travel along one or more rails 106. In one embodiment, the lead powered unit 102 is a locomotive disposed at the front end of the rail vehicle 100 and the trailing units 104 are cargo cars for carrying passengers and/or other cargo. The lead powered unit 102 includes an engine system, for example, a diesel engine system 116. The diesel engine system 116 is coupled to a plurality of traction motors 110 to provide tractive effort to propel the rail vehicle 100. For example, the diesel engine system 116 includes a diesel engine 108 that powers traction motors 110 coupled with wheels 112 of the rail vehicle 100. The diesel engine 108 may rotate a shaft that is coupled with an alternator or generator (not shown). The alternator or generator creates electric current based on rotation of the shaft. The electric current is supplied to the traction motors 110, which turn the wheels 112 and propel the rail vehicle 100. It should be noted that for simplicity and ease of illustration, the traction motors 110 are only shown in connection with one set of wheels 112. However, traction motors 110 may be provided in connection with other wheels 112 or sets of wheels 112 as described herein.
The rail vehicle 100 includes a controller, such as a control module 114 that is communicatively coupled with the traction motors 110 and/or an actuator 117 for controlling the stiffness of springs 132 of a suspension system 142 (both shown in
In various embodiments, dynamic weight management may provide load distribution independently to each of the axles 118. For example, each of the units 102 and 104 may include two sets of wheels 112 corresponding to two trucks 120 (shown more clearly in
The control module 114 may include a processor, such as a computer processor, controller, microcontroller, or other type of logic device, that operates based on sets of instructions stored on a tangible and non-transitory computer readable storage medium. The computer readable storage medium may be an electrically erasable programmable read only memory (EEPROM), simple read only memory (ROM), programmable read only memory (PROM), erasable programmable read only memory (EPROM), FLASH memory, a hard drive, or other type of computer memory.
Thus, as illustrated by the locomotive 122 shown in
The weight redistribution in some embodiments includes a transfer of the weight from the inner axle 118b equally to the outer axles 118a and 118c. The weight redistribution is provided by changing or varying the stiffness of the springs 132 in connection with the suspensions for one or more of the axles 118a-c. For example, in some embodiments, four springs 132 are provided per axle 118a-c. However, weight management including the redistribution of weight is achieved by changing the stiffness of some, but not all of the springs 132.
Referring to
In one embodiment, as shown in
The spring retainer 140 may be any mechanism that arrests and changes and number of active coils 138. It should be noted that although the spring retainer 140 is shown at a top end of the springs 132, the spring retainer 140 may be located on a bottom end of the springs 132. In the illustrated embodiment, the bottom or lower end of the spring 132 is supported on the axle box 134 using, for example, a spring cap. Thus, the variable spring stiffness arrangement 130 includes a mechanism wherein coils 138 at one end of the springs 132 (illustrated at the top end of the springs 132) are (i) locked, which are referred to as locked or arrested coils or (ii) released to change the stiffness of the springs 132. Any coils 138 that are not locked or arrested are active coils 138.
In
Thus, the number of active coils of the springs 132 may be dynamically adjusted, which affects the stiffness of the springs 132 and the corresponding load on the axle 118. In some embodiments, changing of the stiffness of the springs 132 may be initiated based on a user input, for example, based on a user identifying a traction limited mode of operation (e.g., wheel slipping or upcoming rail incline or adverse rail condition). In other embodiments, the changing of the stiffness of the springs 132 may be initiated automatically, for example, based on a sensed or detected traction limited mode of operation using one or more sensor. In these embodiments, upon detecting the traction limited mode of operation or an upcoming traction limited mode of operation, such as based on an identification of the traction limited mode of operation by the sensor, which is communicated to the control module 114, the control module 114 automatically changes the stiffness of the springs 132. A notification of the automatic stiffness change may be provided to an operator, such as via an audible and/or visual indicator.
In the various embodiments, the control module 114 instructs the variable spring stiffness arrangement 130 to change the stiffness of the springs 132, for example, by operating a motor to rotate the spring retainer 140. The rotation of the spring retainer 140 changes the number of coils 138, for example, the number of coil turns that are arrested and, thus changes the stiffness of the springs 132 to redistribute the load among the axles 118 (shown in
For example, if the spring retainer 140 is rotated to increase the number of active coil turns of the coils 138, the stiffness of the springs 132 decreases. The decrease of the stiffness of the springs 132 causes a shift or redistribution of weight among the axels 118, namely to or from the different axles 118.
More particularly, referring to the example in
The spring retainer 140 may be any suitable device for engaging and retaining (in an arrested state) a portion or some of the coils 138 at one or more ends of the springs 132 for changing the stiffness of the springs 132. For example, the spring retainer 140 may be a threaded cap or cup, or may be a threaded bolt or screw mechanism as described herein. Additionally, the springs 132 may be any type of spring, such as any spring suitable for a locomotive suspension.
In an initial state of stiffness, such as when a traction limited mode of operation is not detected, all of the springs 132a, 132b and 132c have the same stiffness. Thus, all of the springs 132a, 132b and 132c have the same or about the same stiffness. As the stiffness of the outer springs 132a and 132b, is increased, the net preload on the inner axle 118b (center axle) changes and the load or weight is redistributed to the outer axles 118a and 118c.
The spring retainer 140 may be implemented in different configurations and arrangements. In the various embodiments, the spring retainer 140 may have a threaded interior or a threaded exterior for engaging coils 138 of the springs 132. It should be noted that other spring retention methods or apparatus may be used. For example, the spring retainer 140 may be a locking device or clamping device that can arrest portions of the springs 132.
In general, the various embodiments provide varying spring stiffness using a threaded spring retainer 140. For example, the spring retainer 140 includes a retaining device that may be located at a top or bottom of the springs 132. As illustrated in
In the embodiment illustrated in
The threaded cap 160 includes one or more inner threads 166 having a size and pitch complementary to the coils 138 of the spring 132 such that when the threaded cap 160 is rotated, the threads 166 engage and retain some of the coils 138 or a portion thereof. It should be noted that the end of the spring 132 opposite the spring end that engages the threaded cap 160 is a fixed end 168 (supported on the truck bed) that receives the compression force, for example, from a load supported by the suspension system of the locomotive 122 (shown in
Thus, as illustrated by
In particular, the stiffness of the spring 132 may be defined in the following Equation 1:
Wherein k represents the stiffness, d=the cross-section diameter of the spring 132, D=the diameter of the spring 132, and N=the number of active coil turns of the spring 132.
In operation, with an increase in the number of active turns (N), the stiffness decreases and with a decrease in the number of active turns (N), the stiffness increases. Thus, the threaded cap 160 can be actuated or driven, such as in a closed loop, to adjust the number of coil turns that are active, thereby changing the stiffness of the spring 132. By adjusting the stiffness of different springs 132, the load or weight of a locomotive may be redistributed as described herein. Thus, by locking a portion of the spring 132 within the threaded cap 160, that portion of the spring 132 becomes ineffective or inactive. As the stiffness of the spring 132 is increased, the load on other springs corresponding to other axles decreases with the load on the stiffened spring increased.
Accordingly, the threaded cap 160 operates with the spring 132 to adjust the stiffness of the spring 132. For example, some turns of the spring 132 are in the threads 166 of the threaded cap 160. The threaded cap 160 holds the spring 132 at one end with the other end of the spring 132 being fixed. By turning or rotating the threaded cap 160 in one direction (illustrated as counterclockwise), a greater number of coil turns are provided and maintained within the threaded cap 160, which decreases the number of active coils 138, thereby increasing the stiffness of the spring 132. By turning the threaded cap 160 in the opposite direction (in the clockwise direction in this example), the number of coil turns in the threaded cap 160 is decreased, which increases the number of active coils 138, thereby decreasing the stiffness of the spring 132. It should be noted that the actuation and movement of the threaded cap 160 can be provided and regulated by any device, such as a motor, etc.
In other embodiments, for example, as illustrated in
In this embodiment, the threaded bolt 170 is supported at a bottom end by the housing of the truck frame. The other end of the threaded bolt 170 is inserted through an opening within the axle box 134 and coupled with a support bearing 178. Each of the threaded bolts 170 is connected at the upper end to a motor 180 via a sprocket 182 and chain drive 184. It should be noted that the motor 180 may be any type of motor, for example, an electric motor, that causes the threaded bolts 170 to rotate using the chain drive 184. Additionally, the connection mechanism for connecting the motor 180 to the threaded bolts 170 may be any suitable coupling means, such as a belt drive, etc. It should be noted that a similar drive mechanism may be used for rotating the threaded cap 160 shown in
In operation, by rotating the threaded bolts 170, the number of arrested coils 138a is changed, which varies the stiffness of the spring 132 as described herein. Thus, by changing the number of ineffective or inactive coils 138, the stiffness of the spring 132 is varied, which changes the load on the springs 132.
It should be noted that separate actuating mechanisms may be provided in connection with each of the springs 132 as illustrated in
Thus, by changing the stiffness of the outer springs 132 of the locomotive 122, weight management is provided by redistributing the load among the axles 118 of the locomotive 122. For example, assuming the following initial conditions, the various embodiments operate to provide weight management as described below:
K1 is the initial stiffness of all the springs 132.
FL1 is the free length of all springs 132 in a normal operating condition.
Delta1 is the deflection of truck platform. It should be noted that all springs deflect equally (delta1=F/3K1)
Each spring also takes an equal load (F/3).
It should be noted that the outer springs 132 of the locomotive suspension corresponding to the outer axles 118 may have extra coil turns (e.g., four extra turns) as compared to the springs 132 of the inner axles 118. The extra coil turns can be provided between the supported ends of the variable spring stiffness arrangement 130 using the spring retainer 140.
In operation, weight management may be provided as follows:
1. Initially all of the springs have a free length FL1, and a spring stiffness K1. The total initial stiffness of all springs is 3*K1.
2. Under the load (F), all of the springs deflect by an equal amount: delta1=F/(3*K1), such that the load taken by each of the springs=F/3.
3. For the outer springs, by turning the spring retainer 140, a greater number of coil turns are inserted between the truck and spring retainer 140. As a result, because of the increase in the number of coil turns between the spring retainer 140 and the truck platform, the outer suspension free length is changed by the spring retainer 140 from FL1 to FL2 (FL1<FL2; K2<K1).
4. Because of the increase in the number of active coil turns (N), there is a reduction in the stiffness of outer suspension from K1 to K2 (as described in connection with Equation 1 herein), such that K2<K1. The total changed stiffness of all of the springs is 2*K2+K1.
Thus, the total initial stiffness of all springs is 3*K1 which is greater than the total changed stiffness of all springs, which is 2*K2+K1.
Accordingly, the change in stiffness results in the following redistribution of load:
1. In the changed final condition, after the application of load F, the truck platform remains parallel to the ground with the free ends of all of the springs at an equal distance from the ground.
2. If the middle or inner spring deflects by an amount delta2, the outer springs deflect with the value delta2+(FL2−FL1) because the free length of the outer springs (FL2) is now more than the free length of the inner spring (FL1).
3. The load taken by the outer suspension is Lo=K2*(delta2+(FL2−FL1)) and the load taken by the inner or middle suspension is Lm=K1*delta2.
4. The effect of preload (K2*(FL2−FL1)) on the outer suspension causes the outer suspension to support a large portion of the load (F).
5. The load taken by inner or middle springs is: Lm=K1*delta2 and the load taken by outer springs is: Lo=K2*(delta2+(FL2−FL1)).
Thus, for example, assuming four suspensions at each end and the load F is increased by four times from 52.5 klbs to 210 klbs., the outer suspension load is increased from 70 klbs (17.5×4) to 90 (22.5×4) klbs and the inner or middle suspension load is reduced from 70 klbs (17.5×4) to 30 (7.5×4) klbs.
A method 210 as shown in
The method 210 then includes mounting the variable spring stiffness arrangement to the vehicle at 214. For example, springs having the variable spring stiffness arrangement may be mounted to the vehicle or a portion thereof, such as the axle box. In some embodiments, the variable spring stiffness arrangement is provided on springs of the outer axles and not on the inner axle of a three axle truck, with two trucks provided per vehicle.
With the variable spring stiffness arrangement mounted with the springs, the stiffness of the springs is controlled at 216 by arresting a portion of the springs. For example, by varying the number of active spring coils, the stiffness of the springs is changed, which redistributes the load among the axles of the vehicle. The controlling may be provided using a control module that dynamically adjusts the number of coil turns of the springs that are arrested. The changes to the stiffness may be based on different factors, such as traction limited modes of operation.
Thus, various embodiments may dynamically control weight distribution by varying the spring stiffness in a vehicle. For example, by varying a number of coil turns that are ineffective or inactive, which may be performed by arresting a number of coil turns, the stiffness of the springs is changed.
The various embodiments may be implemented with no changes to the vehicle frame. For example, the motor and the variable spring stiffness arrangement can be mounted on the vehicle frame on either the inside or outside of the frame.
It is to be understood that the above description is intended to be illustrative, and not restrictive. For example, the above-described embodiments (and/or aspects thereof) may be used in combination with each other. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its scope. While the dimensions and types of materials described herein are intended to define the parameters of the disclosed subject matter, they are by no means limiting and are exemplary embodiments. Many other embodiments will be apparent to those of skill in the art upon reviewing the above description. The scope of the subject matter described herein should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Moreover, in the following claims, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects. Further, the limitations of the following claims are not written in means-plus-function format and are not intended to be interpreted based on 35 U.S.C. §112, sixth paragraph, unless and until such claim limitations expressly use the phrase “means for” followed by a statement of function void of further structure.
This written description uses examples to disclose several embodiments of the above subject matter, including the best mode, and also to enable any person skilled in the art to practice the embodiments of subject matter, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the subject matter described herein is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.
