Cross-drive e-transmission for series hybrid tracked vehicles

Abstract

The invention relates in particular to a cross-drive e-transmission used in electric or series hybrid, tracked or skid-steer wheeled military vehicles, unmanned land vehicles, and construction equipment. In particular, the invention relates to a cross-drive e-transmission, which comprises a drive motor (10) which enables forward and reverse motion of the vehicle; right and / or left steering motors (20, 30) which enable the vehicle to turn right and left in forward and reverse directions by creating a speed difference at the desired level on the left and right output shafts (100), and which enable the vehicle to turn in its existing location without moving in the forward or reverse directions by providing an opposite directional drive to the wheels / track; a differential assembly (60) which transmits the drive received from the drive motor (10) and steering motors (20, 30) to the brake assembly (70, 80) and thus to the wheels / track.

Description

[0001] CROSS-DRIVE E-TRANSMISSION FOR SERIES HYBRID TRACKED VEHICLES

[0002] TECHNICAL FIELD

[0003] The invention relates to a cross-drive electric transmission used in electric and series hybrid, tracked, skid-steer wheeled military vehicles, unmanned land vehicles, and construction equipment.

[0004] In particular, the invention relates to a cross- drive e-transmission which comprises a drive motor that enables forward and reverse motion of the vehicle, steering motors that enable the vehicle to turn to the right and left or to perform pivot maneuvers by creating a speed difference at the desired level on the left and right output shafts, and which transmits the drive conveyed from these motors to the tracks via brake assemblies.

[0005] STATE OF THE ART

[0006] The gearbox, also known as transmission, is a set of gears which transmits the drive from the motor to the shafts, thus to the tracks, at the appropriate speed. The role of the transmission system in tracked vehicles is to change the rotational speed and torque of the motor at an appropriate rate to be transmitted to the tracks. Besides these, its role is also to enable the vehicle to steer by adjusting the difference in the rotation speed of the tracks while steering.

[0007] Today, electric motor driven transmission applications in tracked vehicles generally use either independent drive solutions or cross-drive solutions. In the independent drive solution, each track is driven by 2 separate electric motors and transmissions. On the other hand, in the crossdrive solution, both tracks are driven by the same transmission and there are 2 different electric motors driving this transmission.

[0008] In the state of the art, each track is driven by a motor and gearbox in the independent drive solution, and these motors operate effectively in almost all driving scenarios. However, especially for maneuvers at high speeds, it is necessary to brake the track in the turning direction of the vehicle and to steer the track in the other direction at a higher speed, and this requires the motor driving the track, which is outside the curve to be able to provide very high powers. Since the vehicle must have the ability to turn equally in both directions, very high-powered motors must be used on both tracks.

[0009] Although the cross-drive solutions used in the state of the art are applications with lower overall power requirements, they must have a more complex gear architecture compared to the independent drive method. Additionally, in known cross-drive solutions, one motor is only responsible for the forward motion while the other motor is only responsible for the steering motion. Therefore, when the vehicle is travelling on a straight line, the driving motor operates mostly under load, while the steering motor only consumes a small amount of power to keep the vehicle on a straight path, and thus does not have a direct impact on the mobility performance of the vehicle. Likewise, when performing the pivot movement, also known as point turning movement, which is a capability specific to tracked and skid-steer wheeled vehicles, and which allows the vehicle to turn around its own axis in a very small radius due to the right and left tracks / wheels of the vehicle rotating in opposite directions, the driving motor remains stationary and all the work is taken over by the steering motor. In summary, while in the independent drive solution, for example when the vehicle is accelerating on a straight line or climbing a steep hill, both motors are activated and perform approximately equal work; in the cross-drive solution, only the driving motor performs the work, and the steering motor remains stationary. During the pivot movement, in the independent drive solution, both motors rotate in opposite directions and perform approximately equal work, while in the cross-drive solution, only the steering motor performs work and the driving motor remains stationary.

[0010] When maneuvering at high speeds, while the motor on the outer track is expected to produce very high powers in the independent drive solution, the motor on the inner track works like a generator and instead of consuming power for the movement of the vehicle, it ensures that the vehicle stays on the desired route by braking the vehicle and causes more load to be born by the other motor. Although the electrical energy recovered during this braking operation can be used by the other motor, it is a disadvantageous solution with regard to motor sizing since there is no mechanical transmission of power and all the gain is transferred electrically. On the other hand, in the cross-drive solution, during maneuvers at high speeds, it is allowed that the power, which is conveyed from the driving motor and distributed evenly between the left and right tracks / wheels, to be mechanically transmitted from one side to the other by activating the steering motor, and this allows the movement to be carried out with relatively low power in the steering motor, although the power required to be generated in the driving motor increases slightly in the meantime. This makes it possible to use 2 similar motors of equal and high power in the independent solution, while in the cross-drive solution a smaller steering motor is used in contrast to a larger but single traction motor.

[0011] As a result, in order to solve the above-mentioned problems existing in the state of the art, the need for a novel, affordable, convenient, practical transmission design and the inadequacy of the existing solutions have made it necessary to make an improvement in the related technical field.

[0012] OBJECTIVE OF THE INVENTION

[0013] The present invention relates to a cross-drive e-transmission called "skid steer", in which the vehicle can be steered by creating a speed difference between the right-left wheel or track, rather than steering the wheels for turning movement in order to eliminate the above- mentioned disadvantages and to provide new advantages to the related technical field.

[0014] The most important objective of the invention is to combine the cross-drive and independent drive structures, thereby combining their common advantages. While the left and right tracks are still driven by 2 independent electric motors, a differential gear set and a third drive motor are added which allow mechanical power transfer between these motors. In this way, not only the use of motors with smaller sizes has been made possible, but also an effective and efficient power distribution between the 3 motors has been achieved by distributing duties among the motors. Also, in case of a single motor failure, driving is maintained with the other 2 motors.

[0015] The structural and characteristic features and all advantages of the invention will more clearly understood via drawings given below and the detailed description written with reference to said drawings, and for this reason, the evaluation should be made in consideration of these drawings and the detailed description. DRAWINGS TO HELP UNDERSTAND THE INVENTION

[0016] FIGURE -1 is a schematic view showing the transmission according to the present invention.

[0017] FIGURE -2 is a view showing the transmission according to the present invention.

[0018] FIGURE -3 is a view showing the transmission according to the present invention.

[0019] REFERENCE NUMBERS

[0020] 10. Drive Motor

[0021] 11. Pinion Gear

[0022] 20. Left Steering Motor

[0023] 30. Right Steering Motor

[0024] 40. Left Gearbox

[0025] 50. Right Gearbox

[0026] 60. Differential Assembly

[0027] 61. Ring Gear

[0028] 70. Left Brake Assembly

[0029] 80. Right Brake Assembly

[0030] 90. Intermediate Gear

[0031] 100. Output Shaft DETAILED DESCRIPTION OF THE INVENTION

[0032] This detailed description discloses the preferred embodiments of the customized transmission only for a better understanding of the subject matter and no limitations should be construed.

[0033] Figures 1-3 show the cross-drive e-transmission and details thereof according to the present invention. The pinion gear (11) located on the output shaft of the drive motor (10) transmits power to the ring gear (61) in the differential assembly (60). The differential assembly (60), which is connected to the ring gear (61), transmits this rotational movement to the differential output shafts (100) on the right and left. The part until here is exactly the same as a typical open differential (without lock). One could consider this part as an open differential driven by an electric motor. In the open differential, the tracks driven by the left and right outputs will rotate at equal speeds, assuming that both tracks will move on a flat surface with equal friction surfaces under ideal conditions.

[0034] However, when all other factors such as road slope, friction coefficient variations on the road, obstacles, position of the vehicle's centre of gravity, wind, etc. are combined, it is not possible for these two tracks to rotate at the same speed continuously. The speed of the track in the direction facing the resistance will decrease, while the speed of the other track will increase proportionally. In order to avoid this control problem, we need to change this structure from an open differential to a torque-controlled differential.

[0035] In order to turn the drive motor (10) and differential assembly (60) into a torque-controlled duo and to drive the left and right output shafts (100) of the differential assembly (60), left and right steering motors (20,30) were added to the system to drive the gearboxes (40,50) with two ratios. In order to guarantee the linear movement of the vehicle, the desired route to be followed by the vehicle can be kept under control by controlling the revolutions of the left and right steering motors (20,30). For example, if the vehicle is intended to travel on a straight line, the desired torque will be applied to the drive motor (10) with the help of the accelerator pedal of the vehicle, while the vehicle's steering wheel is also kept in the zero position, and the left and right steering motors (20,30) will rotate in conjunction with the drive motor (10) and at equal speeds, thus ensuring that the vehicle is minimally affected by terrain and other external environmental conditions and thereby continues to travel on a straight route.

[0036] In the case where the vehicle is intended to perform a turning maneuver, the drive motor (10) will again ensure that the vehicle continues to move at a certain speed in response to the torque input from the accelerator pedal, while the steering motors (20,30) will create a speed difference therebetween and ensure that a speed difference at the desired level is created on the left and right output shafts (100). For example, when the steering wheel is turned to the left, the speed of the left steering motor (20) is reduced and at the same time the speed of the right steering motor (30) is increased at the same ratio and thus it will be ensured that the vehicle starts the left turning movement in a controlled manner without any change in the speed of the drive motor (10). The sharper the desired turning movement of the vehicle is, the higher the speed difference between the left and right steering motors (20,30) must be. In summary, as the speed difference between the left and right steering motors (20,30) increases, the turning radius decreases, and as the speed difference decreases, the turning radius also increases proportionally. When the speed difference between the right and left motors (20,30) is zeroed, the vehicle moves on a straight line.

[0037] The duties of the gearboxes (40,50) with two ratios in the system are to bring the output speeds and torques of the left and right steering motors (20,30) to the levels required by the vehicle, and to ensure that the vehicle can be towed by another vehicle with the help of shifting these gearboxes to neutral gear in case of vehicle failure, etc. Especially in scenarios requiring high torque, such as climbing, rough terrain, towing other vehicles, both gearboxes (40,50) are responsible for shifting into first gear to increase the torque produced by the steering motors (20,30) and thus ensure that the desired performance of the vehicle is obtained. In the invention, the drive from both gearboxes (40,50) is transmitted to the differential assembly (60) via the intermediate gear (90). Similarly, both gearboxes must be used in first gear in order for the vehicle to pivot in its current location with the wheels turning in opposite directions without moving forward. In this way, it is aimed to keep the steering motors (20,30) in the lower torque band and to operate at more efficient points by reducing the thermal pulse values. The first gear stage can be used in the forward and pivot motions of the vehicle as well as in the reverse motion, thus enabling the desired performance to be obtained from the vehicle under the same challenging driving conditions.

[0038] Differential assembly (60) combines the steering motion from 3 separate motors (10,20,30) and in addition, during high-speed maneuvers, with reference to the direction of turning of the vehicle, mechanically transfers the energy recovery that occurs during the deceleration of the track in the direction of turning via its gears to the outer track that is outside the direction of turning and needs much higher powers at that time, thus supporting the steering motor driving the outer track. Due to this feature, the high power requirements on the motors (10,20,30) in the independent drive solution can be avoided during high-speed maneuvers. Moreover, another advantage of the differential assembly (60) is that in the event of a failure of either the right or left steering motor (20,30), the vehicle will still be able to perform the desired maneuvers with the help of speed control from the other motor. Likewise, it also allows the right and left steering motors (20,30) to still act independently in the event of a possible failure of the drive motor(10) and it is ensured that all mobility capabilities of the vehicle can still be fulfilled with an acceptable loss of performance even in the event of failure of any one of the 3 motors (10,20,30). In this respect, it is superior to both independent drive and cross-drive methods and eliminates the shortcomings of these two methods.

[0039] The left and right brakes (80,70) are responsible for providing the brake torque necessary to stop the vehicle. In cases where a brake activation solution, where these brakes can be controlled autonomously, is used, it will be possible to ensure that the vehicle can still be steered even if both the left and right steering motors (20,30) fail. By using a brake master cylinder that can control the brake torque distribution between the left and right brakes (70,80) through the steering angle, the control of the left and right steering motors can be improved, and also the maneuverability of the vehicle can be maintained even in the event of a failure of the steering motors (20,30), without the need for additional software-based safety mechanism. And the drive is transmitted to the wheels or track by means of a shaft connected to the outside of the hubs of the brakes (70,80). The scope of protection of this application is set out in the claims and is by no means limited to those described above for illustrative purposes. It is evident that a person skilled in the art can establish the novelty set forth in the invention by using similar embodiments and / or can apply this embodiment to other fields with similar purposes used in the relevant art. Therefore, it is obvious that such embodiments will lack the criterion of novelty and especially the criterion of overcoming the state of the art.

Claims

CLAIMS1- A cross-drive e-transmission used in electric or series hybrid, tracked or skid-steer wheeled military vehicles, unmanned land vehicles, and construction equipment, characterized in that it comprises the following; a drive motor (10) which enables forward and reverse motion of the vehicle, right and / or left steering motors (20,30) which enable the vehicle to turn to the right and left by creating a speed difference therebetween and providing a speed difference at the desired level on the left and right output shafts (100), and which enable the vehicle to turn in its current location without moving in the forward direction by providing an opposite directional drive to the wheels / track, a differential assembly (60) which transmits the drive from the drive motor (10) and steering motors (20,30) to the brake assembly (70,80) and thus to the wheels / track2- Transmission according to claim 1, characterized in that it comprises right and / or left gearbox (40,50) which brings the output speeds and torques of the left and right steering motors (20,30) to the levels required by the vehicle and enables the vehicle to be towed by another vehicle by shifting these gearboxes into neutral gear in cases such as vehicle failure.3- Transmission according to claim 1, characterized in that it comprises right and / or left brake assembly (70,80) which provides the braking torque required to stop the vehicle, and ensures that the vehicle is still steerable in the event of failure of both the left and right steering motors (20,30).4- Transmission according to claim 1, characterized in that it comprises a differential assembly (60), which combines the steering motion received from 3 separate motors (10,20,30) and in addition, during high-speed maneuvers, with reference to the direction of turning of the vehicle, mechanically transfers the energy recovery that occurs during the deceleration of the track in the direction of turning via its gears to the outer track that is outside the direction of turning and needs much higher powers at that time, thus supporting the steering motor (20,30) driving the outer track.5- Transmission according to claim 1, characterized in that it comprises the differential assembly (60) which allows the vehicle to still perform the desired maneuvers with the help of the speed control to be conveyed from the other motor in case of failure of either the right or left steering motors (20,30) .6- Transmission according to claim 1, characterized in that it comprises the differential assembly (60) which ensures that even in the event of failure of either one of the drive motor(10) or the steering motors (20,30), all mobility capabilities of the vehicle are still fulfilled with an acceptable loss of performance.

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