The present invention relates to straddle-type wheeled vehicle braking systems.
Motorized three-wheeled vehicles are well known in the art. Such vehicles are typically off-road type or all-terrain vehicles (also known as “ATVs”). Two different configurations of three-wheeled vehicles are generally known. The first configuration has one wheel at the front and two wheels at the back of the vehicle. The second configuration has two wheels at the front and one wheel at the back.
Regardless of the particular configuration of the three-wheeled vehicle, those skilled in the art recognize that three-wheeled vehicles are intrinsically less stable than four-wheeled vehicles, such as automobiles. Several factors contribute to this instability. For comparable wheelbase, wheeltrack and center of gravity (CG) position, the rollover axes of the three-wheeled vehicle are closer to the CG than they are for a four-wheeled vehicle.
It should be noted at the outset that the lower stability of a three-wheeled vehicle versus a four-wheeled vehicle should not be understood to mean that a three-wheeled vehicle is unstable to the point that it is dangerous to a user. To the contrary, as would be understood by those skilled in the art, some designs of three-wheeled vehicles are inherently very stable and can even advantageously be compared to some four-wheeled vehicles.
Another factor that affects the stability of a vehicle is the center of gravity of the vehicle. The height of the center of gravity of a vehicle is measured as a distance from the ground when the vehicle is at rest. The center of gravity changes based on the rider position and the type of seating arrangement provided.
A straddle seat type vehicle positions the rider higher from the ground and, as a result, typically creates a vehicle with a higher center of gravity than a vehicle that has a recumbent type seat, which may be more stable but requires additional space and have a different weight distribution since the rider cannot be superposed over the engine. Recumbent seat configurations generally position two riders side by side.
While straddle seats may alter disadvantageously the center of gravity of a vehicle, they offer certain advantages that are not available with recumbent seats. In particular, straddle seats allow a more compact riding position, allow a better vision since the driver is higher, make the rider more visible, and permit the rider to lean into a turn for enhanced handling. Straddle seats also may provide a second passenger seat behind the driver seat, if desired, but the additional rider also tends to raise the center of gravity of the vehicle.
An advantage of a tandem straddle-type vehicle is that the center of gravity of the vehicle remains laterally symmetrically positioned if there are one or more riders. In contrast, on a recumbent three-wheeler, when only the driver is present the center of gravity is not located in the same lateral position as when there are two riders in the vehicle. When only a driver is present in a three-wheeled vehicle with recumbent seats, the center of gravity will be offset from the longitudinal centerline of the vehicle in a direction towards the driver. As would be appreciated by those skilled in the art, this offset may have an effect on the handling performance of the recumbent-seated vehicle.
Other factors that affect stability include the distance between the tires. On a vehicle, the wheel base refers to the distance between the front tire(s) and the rear tire(s). The wheel track, on the other hand, refers to the distance between two tires on the same axle. A larger distance between the tires (whether it be the wheel base or the wheel track) enhances the stability of the vehicle, but creates a larger vehicle, in terms of overall length and/or width (as the case may be), which may be less maneuverable because of the vehicle's increased size.
When operating any vehicle, especially a three-wheeled vehicle, stability is a concern during turning. When negotiating a curve, a vehicle is subject to centrifugal forces, as is readily understood by those of ordinary skill in the art of vehicle design. Generally, a higher center of gravity causes the vehicle to have a lower wheel lift threshold with respect to centrifugal forces than a vehicle with a lower center of gravity.
Three-wheeled vehicles raise special stability concerns since there is a smaller total tire contact area with the ground as compared with similarly sized four-wheeled vehicles. Usually three-wheeled vehicles have a smaller weight and therefore they are more sensitive to variations in loading, particularly driver, passenger and cargo weight. Moreover, if a straddle seat is employed, the center of gravity can be relatively high as compared with that of a recumbent three-wheeled vehicle.
To equip a three-wheeled vehicle for road use, road tires must be employed. At high speeds or in sharp turns, the centrifugal forces generated on a road may, under certain conditions, exceed the traction threshold of a road tire, which could cause one or more of the tires to slip on the road surface. The slippage may be so severe that the vehicle could oversteer or understeer under certain circumstances.
As would be appreciated by those skilled in the art, modern road tires can offer considerable grip on a road surface. The gripping force of modern road tires can be so strong, in fact, that a vehicle with a high center of gravity may, under certain conditions, be subjected to forces that may cause the vehicle to exceed its wheel lift threshold. If the wheel lift threshold is exceeded, one or more of the vehicle's wheels on the inner side of the curve may lift off of the road surface. Under such circumstances, if the rider continues to apply a lateral acceleration to the vehicle, the vehicle may rollover. Tripped rollover can also be experienced under severe oversteering conditions if the tires suddenly recover traction with the ground or hit an obstacle side ways.
Electronic stability systems (ESS), also known as vehicle stability systems (VSS), are designed to electronically manage different systems on an automotive vehicle to influence and control the vehicle's behavior. An ESS can manage a considerable number of parameters at the same time. This provides an advantage over an automotive vehicle merely operated by a person since the driver can only manage a limited number of parameters at the same time. A typical ESS takes several inputs from the vehicle and applies different outputs to the vehicle to influence the vehicle's behavior. Examples of inputs include steering column rotation, the longitudinal and transverse acceleration of the vehicle, the engine output, the detection of the presence (or absence) of a rider and a passenger, the speed of the four wheels, the brake pressure in the wheel's brakes, the yaw rate, and the yaw rate angle. Traditional ESSs use inputs from all four wheels (on a four wheel vehicle). Some low-cost systems use reduced inputs, but this does not result in optimal behavior interpretation. Inputs from suspension displacement, brake and accelerator pedals displacement can also be provided to the ESS.
The outputs from the ESS affect an automobile's behavior by generally independently managing the brakes on each wheel, the suspension, and the power output of the engine in order to improve the automobile's handling under certain circumstances. Since ESSs have been specifically developed for four-wheeled vehicles and rely on inputs provided by a four-wheeled vehicle, it is time consuming to adapt this kind of system to a three-wheeled vehicle. This is especially true since an ESS typically uses inputs from each of the four wheels independently and uses the braking system independently on all of the wheels.
A three-wheeled vehicle configured with a single wheel at one end of the vehicle does not provide all the information/data input required by a four-wheeled vehicle ESS. For example in a two front wheels, one rear wheel configuration, there is only one rear wheel from which the ESS can receive input on speed. Typically, on a vehicle having four wheels, when the brake is applied to one of the rear wheels, a yaw moment is generated about a vertical axis passing through the center of gravity of the vehicle. On a vehicle having only one rear wheel, the rear wheel is positioned in the same plane as the longitudinal axis of the vehicle, which makes it difficult to generate any significant yaw moment by applying the brake to the rear wheel.
Furthermore, to date, few three-wheeled vehicles have been produced commercially for road use. Therefore, it is difficult to determine the preferred settings of drivers of such vehicles. This is especially true for a three-wheeled vehicle having a straddle seat. Some people may consider this type of vehicle to be a hybrid between a motorcycle, which typically has a hand actuated brake, and an automobile, which usually has a foot actuated brake. Therefore, on a three-wheeled vehicle having a straddle seat, different people may have different preferences when it comes to the type of actuation for the brakes. Thus, this creates a difference in the design of the braking system.
Therefore, there is a need to provide a braking system for a straddle-type three-wheeled vehicle which responds to the preferences of most drivers.
There is also a need to provide such a braking system that can function with an ESS.
One aspect of the invention provides a straddle-type wheeled vehicle having a hand brake lever, a foot brake lever, and a master cylinder hydraulically actuating a brake in response to actuation of either of the foot and hand brake levers.
Another aspect of the invention provides a straddle-type three-wheeled vehicle having a first brake lever, a second brake lever, a master cylinder, and an electronic brake control unit for actuating the brakes of the vehicle.
In another aspect, the invention provides a straddle-type wheeled vehicle having a frame, a straddle seat mounted to the frame, a first wheel and a second wheel mounted to the frame near a first end thereof, and a third wheel mounted to the frame near a second end thereof. A steering assembly is mounted to the frame forwardly of the straddle seat for steering at least one of the wheels. An engine is mounted to the frame to provide power to at least one of the wheels. The vehicle has a first brake for braking one of the first and second wheels and a second brake for braking the other of the first and second wheels. An electronic brake control unit operatively communicates with the first brake and separately operatively communicates with the second brake. A sensor senses an operating condition of the vehicle and is in operative connection with the electronic brake control unit for sending an operating condition signal to the electronic brake control unit. A master cylinder hydraulically communicates with the electronic brake control unit. The vehicle also has a first brake lever for actuating the master cylinder and a second brake lever for actuating the master cylinder. The master cylinder hydraulically actuates the first and second brakes through the electronic brake control unit in response to actuation of either of the first and second brake levers. The electronic brake control unit selectively actuates the first and second brakes in response to the operating condition signal independently of actuation of the master cylinder.
In a further aspect, the vehicle also has a third brake for braking the third wheel. The master cylinder hydraulically communicates with the third brake separately from the first and second brakes and hydraulically actuates the third brake in response to actuation of either of the first and second brake levers.
In an additional aspect, the first brake lever is a foot brake lever mounted to the vehicle at a location below the straddle seat and the second brake lever is a hand brake lever mounted to the steering assembly.
In yet another aspect, the invention provides a straddle-type wheeled vehicle having a frame, a straddle seat mounted to the frame, a front wheel mounted to the frame near a front thereof, and a rear wheel mounted to the frame near a rear thereof. A steering assembly is mounted to the frame forwardly of the straddle seat for steering the front wheel. An engine is mounted to the frame for providing power to at least one of the wheels. The vehicle has a first brake for braking one of the wheels. A master cylinder hydraulically communicates with the first brake. A foot brake lever is mounted to the frame at a location below the straddle seat for actuating the master cylinder, and a hand brake lever is mounted to the steering assembly for actuating the foot brake lever. The master cylinder hydraulically actuates the first brake in response to actuation of either of the foot and hand brake levers.
In a further aspect, the foot brake lever is capable of actuating the master cylinder independently of the hand brake lever.
In an additional aspect, the vehicle also has a slave cylinder operatively connected to the foot brake lever and hydraulically communicating with the hand brake lever. The slave cylinder actuates the foot brake lever in response to actuation of the hand brake lever.
In yet another aspect, the invention provides a straddle-type wheeled vehicle having a frame, a straddle seat mounted to the frame, a first wheel mounted to the frame near a first end thereof, and a second wheel mounted to the frame near a second end thereof. A steering assembly is mounted to the frame forwardly of the straddle seat for steering at least one of the wheels. An engine is mounted to the frame for providing power to at least one of the wheels. The vehicle has a first brake for braking the first wheel and a second brake for braking the second wheel. An electronic brake control unit is in operative communication with the first brake and in separate operative communication with the second brake. A sensor senses an operating condition of the vehicle and is in operative connection with the electronic brake control unit for sending an operating condition signal to the electronic brake control unit. The vehicle also has a first hydraulic brake actuator hydraulically communicating with the electronic brake control unit. A first brake lever actuates the first hydraulic brake actuator. The vehicle also has a second hydraulic brake actuator hydraulically communicating with the electronic brake control unit. A second brake lever actuates the second hydraulic brake actuator. The first hydraulic brake actuator hydraulically actuates the first brake through the electronic brake control unit in response to actuation of the first brake lever. The second hydraulic brake actuator hydraulically actuates the second brake through the electronic brake control unit in response to actuation of the second brake lever. The electronic brake control unit selectively actuates the first and second brakes in response to the operating condition signal independently of actuation of first and second hydraulic brake actuators.
For purposes of this application, terms used to locate elements on the vehicle, such as “front”, “back”, “rear”, “left”, “right”, “up”, “down”, “above”, and “below”, are as they would normally be understood by a rider of the vehicle sitting on the vehicle in a forwardly facing, driving position. The term “longitudinal” means extending from the front to the back. The terms “brake lever” refers to the device through which a driver of the vehicle applies braking, such as, for example, a hand or foot brake lever, a handle, or a brake pedal. A “hand brake lever” is a brake lever that is normally actuated by a driver's hand. Similarly, a “foot brake lever” is a brake lever that is normally actuated by a driver's foot.
Embodiments of the present invention each have at least one of the above-mentioned aspects, but do not necessarily have all of them.
Additional and/or alternative features, aspects, and advantages of the embodiments of the present invention will become apparent from the following description, the accompanying drawings, and the appended claims.
For a better understanding of the present invention, as well as other aspects and further features thereof, reference is made to the following description which is to be used in conjunction with the accompanying drawings, where:
The present invention will be described herein with respect to a vehicle 10 in having a straddle seat 12, two front wheels 14, and one rear wheel 16, as illustrated in FIGS. 1 to 6A. However, it is contemplated that the vehicle 10 could also have one front wheel and two rear wheels. It is also contemplated that some aspects of the present invention could be used in straddle-type vehicles having other wheel configurations.
As seen in FIGS. 1 to 6A, the vehicle 10 has a straddle seat 12 located at least partially rearwardly of a center of the vehicle 10 and disposed along the longitudinal centerline 18 (
A steering assembly is disposed forwardly of the straddle seat 12 to allow a driver to steer the two front wheels 14. The steering assembly has handlebars 26 connected to a steering column 28 (
A pair of driver foot pegs 36 are provided on either sides of the vehicle 10 below the first portion 20 of the straddle seat 12 for a driver to rest his feet thereon. Similarly a pair of passenger foot pegs 38 are provided on either sides of the vehicle 10 below the second portion 22 of the straddle seat 12 for a passenger to rest his feet thereon. Another brake lever, in the form of a foot brake lever 40, is provided on a right side of the vehicle 10 below the first portion 20 of the straddle seat 12 for braking the vehicle 10, as will be explained in greater details below. As best seen in
Each of the two front wheels 14 is mounted to the frame 42 (
The rear wheel 16 is mounted to the frame 42 via a swing arm 56. The swing arm 56 preferably has two arms pivotally mounted at a front thereof to the frame 42 and between which the rear wheel 16 is rotatably mounted at the rear of the two arms. A shock absorber 58 is disposed between the swing arm 56 and the frame 42. The rear wheel 16 has a tire 60 thereon which is suitable for road use. Preferably, the tire 60 is wider than the tires 46. It is contemplated that the tire 60 could have a smaller width or the same width as the tires 46. It is also contemplated that the rear wheel 16 could have two or more tires disposed next to each other thereon. The tire 60 is preferably inflated to a pressure between 138 kPa and 345 kPa. A fairing 62 is disposed over the tire 60 to protect the driver from dirt and water which can be lifted by the tire 60 while it is rolling. The rear wheel 16 is provided with a brake 64. As best seen in
Many other components not specifically described in this application are mounted to the frame 42 to permit proper operation of the vehicle 10. Examples of these components are an air box, radiators, fuel tank, oil tank, and a battery. An exhaust pipe 76 extending on the right side of the vehicle 10 towards the rear thereof is attached to an exhaust port (not shown) of the engine 32 to improve engine performance and to reduce the noise level of the engine 32. A vehicle body 78 is attached to the frame 42 in order to protect the components mounted to the frame 42 from the elements and to make the vehicle 10 aesthetically pleasing. Components necessary to make vehicle 10 suitable for road use, such as lights 80 and a rear view mirror 82, are mounted to the vehicle body 78.
As previously discussed, vehicles such as the one illustrated in
One feature of a three-wheeled vehicle, such as the vehicle 10, that differs from a four-wheeled vehicle results from the triangular shape of the three-wheeled vehicle. In particular, the triangular shape establishes roll axes 84, 86 that are not parallel to the longitudinal centerline 18 of the vehicle.
Although it may be possible for a driver to manually obtain this corrective effect by applying the correct braking force to the correct wheel, it would be very difficult for the driver to assess the proper amount of braking force to be applied. Should the driver apply the braking force to the incorrect wheel, then the result would increase the instability of the vehicle 10. Current systems brake the wheels evenly for that very reason. Also, the reaction time of the typical driver is too slow to achieve proper control. For these reasons, the vehicle 10 is provided with an electronic stability system (ESS).
The ESS uses an electronic control unit (ECU) (not shown). The ECU is responsible for electrical, electronic and closed loop control functions, including power supply to system sensors, recording operating conditions, converting, manipulating, and transmitting data, and network linkage to other controllers if desired. The ECU receives inputs from various sensors located on the vehicle 10 and other vehicle operating systems. The sensors can include, but are not limited to, a steering sensor, an acceleration sensor, a roll rate sensor, a pitch rate sensor (all not shown), and a yaw sensor 96 (
Based on the operating condition signals, the electronic brake control unit 98 will determine which of the brakes 50, 64 need to be actuated to maintain vehicle stability. For example, if a clockwise yaw moment Yv, as in
As best seen in
The construction of the electronic brake control unit 98 allows it to control actuation of the brakes 50, 64 it two ways. The first way consists in regulating the flow of hydraulic fluid to the brakes 50, 64 when the hand or foot brake lever 34, 40 is actuated, as will be explained in greater details below. The second way consists in actuating the brakes 50, 64 in response to the operating condition signal even when neither of the hand and foot brake levers 34, 40 have been actuated. This is achieved by actuating the pump 100 to pressurize hydraulic fluid and using that fluid to actuate the brakes 50, 64. It is contemplated that the pump 100 could be used to boost hydraulic pressure in the braking system when the hand or foot brake 34, 40 is actuated as well.
As previously mentioned, some people may consider the vehicle 10 to be similar to a motorcycle, which typically has a hand actuated brake, while others may consider it to be similar to an automobile, which usually has a foot actuated brake, and may thus like to brake the vehicle 10 with the corresponding brake lever type. Therefore, on a three-wheeled vehicle 10 having a straddle seat 12, different people may have different preferences and/or instincts when it comes to the type of actuation for the brakes, which is why the present vehicle 10 has been provided with both a hand brake lever 34 and a foot brake lever 40. However, the electronic brake control unit 98 should preferably be able to control the brakes 50, 64 in the same way regardless of which brake lever 34 or 40 the driver prefers, so as to not increase the complexity of the electronic brake control unit 98.
In
Therefore, when a rider actuates the hand brake lever 34, it causes the slave cylinder 108 to actuate the foot brake lever 40. The foot brake lever 40 then actuates the master cylinder 106 via linkage 120. It is also contemplated that the hand brake lever 34 could directly mechanically actuate the foot brake lever 40 without the assistance of hydraulic components such as the slave cylinder 108. When a rider actuates the foot brake lever 40, it actuates the master cylinder 106 via linkage 120. Although actuating the hand brake lever 34 actuates the foot brake lever 40, it will be understood by those skilled in the art that actuating the foot brake lever 40 does not actuate the hand brake lever 34 due to the hydraulic nature of the communication between these two components.
The master cylinder 106 hydraulically communicates with the front brakes 50 via brake line 122. The master cylinder 106 also hydraulically communicates with the rear brake 64 via brake line 124, thus creating two independent hydraulic circuits. Keeping the hydraulic communications between the master cylinder 106 and the front and rear brakes 50,64 separate allows the vehicle 10 to brake even if one of the hydraulic circuits fails. For the same reason, the hydraulic fluid is supplied to the master cylinder 106 by two different hydraulic fluid reservoirs 126, 128. The hydraulic fluid reservoir 126 supplies the master cylinder 106 with hydraulic fluid to actuate the front brakes 50. The hydraulic fluid reservoir 128 supplies the master cylinder 106 with hydraulic fluid to actuate the rear brakes 64.
As can be seen in
By having the master cylinder 106 actuate the brakes 50, 64 through the electronic brake control unit 98, the electronic control unit 98 can selectively control actuation of the brakes 50, 64 with the valves 103a to 103c. When the master cylinder 106 is actuated by either of the hand brake lever 34 and the foot brake lever 40 and an operating condition signal received by the electronic brake control unit 98 is outside of a predetermined range, which is indicative of an instability of the vehicle 10, the electronic brake control unit 98 controls the valves 103a to 103c to obtain a braking force, as described above, that will provide a corrective effect, thus stabilizing the vehicle. For example, if the electronic brake control unit 98 determines that a braking force needs to be applied to the front left tire 14, as in
As seen in
Although the braking mechanism shown in
Modifications and improvements to the above-described embodiments of the present invention may become apparent to those skilled in the art. The foregoing description is intended to be exemplary rather than limiting. The scope of the present invention is therefore intended to be limited solely by the scope of the appended claims.
This application is related to but does not claim priority to U.S. patent application Ser. No. 10/920,226, filed Aug. 18, 2004, entitled “Electronic Stability System on a Three-Wheeled Vehicle”, the entirety of which is incorporated herein by reference.
Number | Date | Country | |
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Parent | 10708063 | Feb 2004 | US |
Child | 11379405 | Apr 2006 | US |