Tire steering detection device and synchronous steering correction mechanism for chassis dynamometer

Abstract

The utility model relates to a tire steering detection device and a synchronous steering correction mechanism for a chassis dynamometer, and belongs to the technical field of automobile chassis testing. On one hand, the tire steering detection device is arranged to detect the steering data of the wheels in real time, and after the tire steering detection device communicates with the second driving assembly, the second driving assembly controls and corrects the rotation condition of the rotary drum according to the steering data, so that the rotation condition is synchronous and consistent with the steering of the wheels; the testing and correcting mode is high in measurement accuracy and fast in response and correction, and the defect that a traditional dynamometer cannot rotate along with the tire can be thoroughly overcome. And on the other hand, the speed and the drum surface force of the rotary drum can be controlled and calculated through the first driving assembly, so that various driving scenes of the automobile tire arranged on the rotary hub are simulated and adapted, and the adaptability is wide.

Description

TECHNICAL FIELD

[0001] The utility model relates to a tire steering detection device for chassis dynamometer, synchronous steering correction mechanism belongs to automobile chassis test technical field. BACKGROUND

[0002] The automobile chassis dynamometer adopts different size rollers, uses full-electric inertia simulation technology, can accurately simulate various road loads received by the vehicle in the road driving process, and can be used for the test of vehicle emission, endurance mileage, power performance, durability and the like of the automobile. The equipment can simulate different forces, speeds and road load distribution for each wheel of the vehicle through the separate control of four motors, and can realize different test conditions under the differential condition of the vehicle.

[0003] At present, the "electrification" and "intelligentization" of automobiles develop rapidly, and advanced auxiliary driving and automatic driving vehicles also develop rapidly. Compared with the previous traditional vehicles, more millimeter wave radars, ultrasonic radars, laser radars and machine vision and the like multi-sensor are installed on the L2 and above advanced driving vehicles, through the collection of external environment information by each sensor, the synchronous processing and final decision of a large amount of information by each sub-control system and the total control system, the auxiliary driving of L2 and above higher level is realized.

[0004] Combined with a large number of real road scenes, the in-loop function test and safety evaluation of the whole vehicle with a large number of sensors of the advanced driving vehicle is a very difficult problem in the whole automobile industry at present. At present, in addition to simulation and part in-loop test, closed and open road test, how to realize the test of the vehicle at medium and high speed, close to the real road environment and high-risk road scene is also very important, and it is necessary to develop a chassis dynamometer with steering, which can realize straight driving and steering function on the test platform in combination with real traffic scene library and automobile in real scene, for verifying the medium and high speed driving test and safety evaluation of various auxiliary functions of the automobile in the future. However, there are few reports on the chassis dynamometer with steering in the prior art.

[0005] In addition, with the gradual increase of the test demand of the wheel steering function, most of the vehicle enterprises make the steering data of the vehicle steering control system confidential, so that the vehicle enterprises cannot provide the tire steering angle data of the test vehicle, and therefore there is a higher challenge to the synchronization of the steering function test in automobile driving, especially the test of the steering angle and the like data of the automobile tire during steering. However, the traditional chassis dynamometer can only realize the straight driving of the automobile, and cannot meet the measurement of various functions and angle data tests of the wheel rotation of the automobile during steering.

[0006] In the prior art, there is a hub following system and a vehicle chassis dynamometer equipped with the system provided by CN113607431A, which can rotate with the wheels, but cannot solve the problem of large-angle rotation (rotation angle ± 180 degrees) of the vehicle when the vehicle is driven and braked at low, medium and high speeds. During operation, the front and rear of the test vehicle body have a large swing, especially when turning, the vehicle body will suddenly swing left and right, and the instability and sudden stall of the vehicle body will also cause serious safety problems. Practical new type content

[0007] To solve the above problems, in the first aspect, the application provides a tire turning detection device for a chassis dynamometer, which is applied to a vehicle being tested in a medium and high speed test and a laboratory environment, can test the tire turning angle of the vehicle in real time, and synchronously adjusts the structure of the turntable of the chassis dynamometer. It also provides a solution to the problem that the vehicle is not controlled when the vehicle is accelerated and decelerated and turned at medium and high speeds, comprising:

[0008] A base is fixed to the chassis dynamometer, and distance measuring sensors are arranged on both sides of the base;

[0009] A hub connecting module includes an inner ring rotating disc and a plurality of rotating bolts distributed on the inner ring rotating disc, the rotating bolts are connected to the hub of the vehicle to be tested, and the inner ring rotating disc rotates synchronously with the hub;

[0010] A turning following module includes an outer ring disc, a universal connector and a buffer connecting piece connected in sequence, the rotating shaft of the inner ring rotating disc is assembled in the outer ring disc through a bearing, the outer ring disc is provided with light curtain plates on both sides, and the buffer connecting piece is assembled in the base;

[0011] When the vehicle to be tested turns, the outer ring disc drives the light curtain plate to rotate synchronously with the wheels, the distance measuring sensor can emit laser light, and the laser light can always reach the light curtain plate.

[0012] Further, the universal connector includes a cross shaft, a first steering knuckle connected to the outer ring disc, and a second steering knuckle connected to the buffer connecting piece, the cross shaft includes two shaft bodies perpendicular to each other and connected at the center, and the first steering knuckle and the second steering knuckle are respectively installed on the two shaft bodies.

[0013] Further, the base includes an L-shaped vertical plate and a fixing plate connecting the bottom of the vertical plate and the chassis dynamometer, the L-shaped vertical plate has at least one vertically arranged strip hole, and the buffer connecting piece is installed in the strip hole; the distance measuring sensors are installed on both sides of the L-shaped vertical plate.

[0014] Further, the buffer connector comprises a buffer bolt penetrating through the strip-shaped hole, one end of the buffer bolt is connected with the universal connector, the other end of the buffer bolt penetrates out of the strip-shaped hole, and buffer seats are arranged on both sides of the assembly position of the buffer bolt and the strip-shaped hole.

[0015] Further, the L-shaped vertical plate is provided with a plurality of positioning holes at different heights on the side away from the wheel, a positioning bolt is arranged in each positioning hole, and the positioning bolt is connected with the buffer seat through a traction spring. The buffer seat has an arc-shaped contact surface which abuts against the two side surfaces of the L-shaped vertical plate, that is, the two sides of the L-shaped vertical plate are both provided with the buffer seat, and the arc-shaped contact surfaces of the buffer seats on the two sides are oppositely arranged and both face the L-shaped vertical plate.

[0016] Further, the buffer bolt is sleeved with an inside spring between the universal connector and the L-shaped vertical plate, and is sleeved with an outside spring at the part penetrating out of the strip-shaped hole.

[0017] In the second aspect, the application provides a synchronous steering correction mechanism for a chassis dynamometer, comprising:

[0018] A drum assembly is in contact with the bottom of the wheel of the automobile to be measured, the drum assembly comprises two drums arranged side by side, the wheel is located in a groove formed between the two drums and is in contact with the two drums, and under the driving of a first driving assembly, the two drums rotate synchronously, and the wheel can rotate synchronously with the two drums.

[0019] A drum steering mechanism carries the drum assembly and is connected with the tire steering detection device.

[0020] A rotary support mechanism is arranged at the bottom of the drum steering mechanism and is connected with the chassis dynamometer, the rotary support mechanism is driven to operate by a second driving assembly and can carry the drum steering mechanism and the drum assembly to rotate together, and the second driving assembly can communicate with the distance measuring sensor.

[0021] The first driving assembly comprises a drum driving motor installed in the drum steering mechanism, a motor synchronous pulley connected with the drum driving motor, and two drum synchronous pulleys respectively installed on the two drums, and the motor synchronous pulley is connected with the two drum synchronous pulleys through a synchronous belt.

[0022] The second driving assembly comprises a steering driving motor installed in the drum steering mechanism and a speed reducer connected with the steering driving motor, and the speed reducer is connected with a driving pinion.

[0023] The rotary support mechanism comprises a ring gear connected with the bottom of the drum steering mechanism, the ring gear is meshed with the driving pinion, and a rotation angle measuring mechanism is further arranged below the ring gear.

[0024] The application has the following beneficial effects:

[0025] The present application is characterized in that the tire steering detection device is used to detect the steering data of the wheel in real time, and the second driving assembly is used to control the rotation of the correction drum according to the steering data after the communication between the tire steering detection device and the second driving assembly, so that the rotation of the wheel is synchronized with the steering, and the test and correction are accurate and fast, and the problem that the traditional dynamometer cannot follow the rotation of the tire is solved; on the other hand, the speed and drum surface force of the drum can be controlled and calculated by the first driving assembly, so as to simulate and adapt to various driving scenes of the automobile tire placed on the hub, and the adaptability is wide, and the automobile to be tested can realize the functions of straight driving and steering on the test platform under the condition of real scene, and the various auxiliary driving functions of the electric and intelligent automobile can be verified in the future, and the test, research and development, safety evaluation and other functions of the high-risk road scene under the condition of medium and high speed driving close to the real road environment are realized. In addition, the tire steering detection device of the present application can better adapt to various vibrations, multi-azimuth angles and swing angles generated by the wheel during steering, and can adapt to the large-angle rotation (rotation angle ± 180 degrees) of the vehicle during driving and braking, and the large swing of the vehicle body, and improve the safety. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 FIG. 1 is a three-dimensional structural schematic diagram of the tire steering detection device in an embodiment of the present application.

[0027] Figure 2 FIG. 2 is a side view of the tire steering detection device in an embodiment of the present application.

[0028] Figure 3 FIG. 3 is a top view of the tire steering detection device in an embodiment of the present application.

[0029] Figure 4 FIG. 4 is a schematic diagram of the principle of the universal connector adapting to the front and rear toe angles and camber angles generated by the tire during steering (one shaft body is shown) (side view perspective).

[0030] Figure 5 FIG. 5 is a schematic diagram of the distance measuring principle of the distance measuring sensor (top view perspective).

[0031] Figure 6 FIG. 6 is a three-dimensional structural schematic diagram of the tire steering detection device installed in the synchronous steering correction mechanism from one perspective in an embodiment of the present application.

[0032] Figure 7 FIG. 7 is a side view of the tire steering detection device installed in the synchronous steering correction mechanism in an embodiment of the present application.

[0033] Figure 8 Figure 3 is a schematic view of a three-dimensional structure of a tire turning detection device according to an embodiment of the present application.

[0034] In the figure, 1 is a tire turning detection device; 2 is a drum; 3 is a drum turning mechanism; 4 is a ring gear; 5 is a drum driving motor; 6 is a turning angle measuring mechanism; 7 is a driving pinion; 8 is a speed reducer; 91 is a motor synchronous pulley; 92 is a synchronous belt; 93 is a drum synchronous pulley; 94 is an intermediate pulley; 11 is a base; 111 is a distance measuring sensor; 12 is a light curtain plate; 13 is a universal connector; 14 is a swivel bolt; 15 is an inner ring swivel plate; 16 is an outer ring plate; 17 is a first steering knuckle; 18 is a second steering knuckle; 191 is a buffer bolt; 192 is a positioning bolt; 193 is a traction spring; 194 is a buffer seat; 195 is an inner side spring; 196 is an outer side spring; and 10 is a tire. DETAILED DESCRIPTION

[0035] The technical solutions of the present application will be described clearly and completely below with reference to the drawings. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0036] In the description of the present application, it should be noted that the orientations or positional relationships indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first" and "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance. Among them, the terms "first position" and "second position" are two different positions.

[0037] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connection" should be understood broadly, for example, it can be fixed connection, or it can be detachable connection; it can be mechanical connection, or it can be electrical connection; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication between two elements inside. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0038] Embodiment 1

[0039] AsFigures 1-4 As shown in the drawings, the application provides a tire steering detection device for chassis dynamometer, comprising:

[0040] A base 11 is fixed to the chassis dynamometer, and distance measuring sensors 111 are arranged on both sides of the base 11; the base 11 comprises an L-shaped vertical plate and a fixing plate connecting the bottom of the vertical plate and the chassis dynamometer, the L-shaped vertical plate has at least one vertically arranged strip hole, and a buffer connecting piece is installed in the strip hole; the distance measuring sensors 111 are installed on both sides of the L-shaped vertical plate;

[0041] A hub connecting module comprises an inner ring rotating disc 15 and a plurality of rotating bolts 14 distributed on the inner ring rotating disc 15, the rotating bolts 14 are connected to the hub of the vehicle to be tested, and the inner ring rotating disc 15 rotates synchronously with the hub;

[0042] A steering following module comprises an outer ring disc 16, a universal connector 13 and a buffer connecting piece connected in sequence, the rotating shaft of the inner ring rotating disc 15 is assembled in the outer ring disc 16 through a bearing, the outer ring disc 16 is provided with a light curtain plate 12 on both sides, and the buffer connecting piece is assembled in the base 11;

[0043] When the vehicle to be tested steers, the outer ring disc 16 drives the light curtain plate 12 to rotate synchronously with the wheel. No matter where the light curtain plate 12 rotates with the wheel, the distance measuring sensors 111 can emit laser light, and the laser light can always reach the light curtain plate 12.

[0044] Further, the universal connector 13 comprises a cross shaft, a first steering knuckle connected to the outer ring disc 16 and a second steering knuckle connected to the buffer connecting piece, the cross shaft comprises two shaft bodies which are perpendicular to each other and connected at the center, and the first steering knuckle and the second steering knuckle are respectively installed on the two shaft bodies. The universal connector 13 can adapt to the inclination angle and the swing angle generated when the tire steers, for example, Figure 4 As shown in the drawings, when the wheel generates an inclination angle or a swing angle of up and down, the steering knuckle corresponding to one of the shaft bodies will rotate by a small angle, so as to make the inner ring rotating disc 15, the outer ring disc 16 and the rotating bolt 14 at the front end adapt to the up and down floating of the wheel 10; in actual operation, the up and down floating of the wheel 10 often occurs, and the existing technology does not consider this problem when detecting steering, and the application can effectively overcome such problems compared with the existing technology.

[0045] Further, the buffer connector comprises a buffer bolt 191 penetrating the strip-shaped hole, one end of the buffer bolt 191 is connected with the universal connector 13, the other end of the buffer bolt 191 penetrates the strip-shaped hole, and the buffer bolt 191 is provided with a buffer seat 194 on both sides of the assembly position of the buffer bolt 191 and the strip-shaped hole. The buffer seat 194 has an arc-shaped contact surface, which abuts against the two side surfaces of the L-shaped vertical plate, that is, the two sides of the L-shaped vertical plate are both provided with the buffer seat 194, and the arc-shaped contact surfaces of the buffer seats 194 on the two sides are oppositely arranged and both face the L-shaped vertical plate. Since the universal connector 13 also floats up and down with the wheel 10, the traditional connection position is not provided with the universal connector 13, and the connection structure is fixed, and after floating for many times, the upper and lower parts of the connection component are easily damaged; however, the buffer bolt 191 and the buffer seat 194 of the present application are connected with the universal connector 13, and when the universal connector 13 floats up and down, since one side of the buffer seat abutting against the L-shaped plate is an arc-shaped contact surface, the up and down floating can be better adapted, that is, the buffer seat 194 can carry the buffer bolt 191 and the universal connector 13 to slightly float up and down along the arc line of the arc-shaped contact surface, so that the damage of the connection position can be avoided.

[0046] Further, the side of the L-shaped vertical plate away from the wheel 10 is provided with a plurality of positioning holes at different heights, a positioning bolt 192 is arranged in each positioning hole, and the positioning bolt 192 is connected with the buffer seat 194 through a traction spring. In this way, the second steering knuckle 18 and the downward gravity of the assembly can be better balanced, the flexibility in the left and right directions of the vehicle axis can be better, and the up and down bouncing of the vehicle during acceleration and deceleration can be better adapted.

[0047] Further, the part of the buffer bolt 191 between the universal connector 13 and the L-shaped vertical plate is sleeved with an inner spring, and the part of the buffer bolt 191 penetrating the strip-shaped hole is sleeved with an outer spring 196. After the inner spring 195 and the outer spring 196 are arranged, the buffer bolt 191 and the buffer seat 194 can be further provided with a buffering and damping effect when the wheel 10 floats up and down or forward and backward.

[0048] Embodiment 2

[0049] As shown in Figures 6-8 The present embodiment provides a synchronous steering correction mechanism for a chassis dynamometer, which comprises:

[0050] A drum assembly is in contact with the bottom of the wheel of the automobile to be measured, the drum assembly comprises two drums 2 arranged side by side, the wheel 10 is located in a groove formed between the two drums 2 and is in contact with the two drums 2, and under the driving of the first driving assembly, the two drums 2 rotate synchronously, and the wheel 10 can rotate synchronously with the two drums 2;

[0051] A drum steering mechanism, which carries the drum assembly and connects the tire steering detection device 1 described in embodiment 1;

[0052] A rotary support mechanism, which is arranged at the bottom of the drum steering mechanism 3 and connects the chassis dynamometer, is driven and operated by a second driving assembly and can carry the drum steering mechanism 3 and the drum assembly to rotate together, and the second driving assembly can communicate with the distance measuring sensor 111 through the control system.

[0053] Specifically, the first driving assembly includes a drum driving motor 5 installed inside the drum steering mechanism 3, a motor synchronous pulley 91 connected to the drum driving motor 5, and two drum synchronous pulleys 93 respectively installed on the two drums, and the motor synchronous pulley 91 connects the two drum synchronous pulleys 93 through a synchronous belt 92.

[0054] Specifically, the second driving assembly includes a steering driving motor installed inside the drum steering mechanism 3, a speed reducer 8 connected to the steering driving motor, and a driving pinion 7 connected to the speed reducer 8.

[0055] Specifically, the rotary support mechanism includes a ring gear 4 connected to the bottom of the drum steering mechanism, which is engaged with the driving pinion 7 and driven to rotate by the driving pinion 7 under the drive of the speed reducer, thereby driving the drum steering mechanism 3 and the drum 2 to rotate together; a rotation angle measuring mechanism 6 is also arranged below the ring gear 4, which measures the angle of rotation of the entire rotary support mechanism. In addition, the rotary support mechanism can also simulate the rotary resistance of the vehicle when steering on the ground through the resistance calculation of the driving part.

[0056] Embodiment 3

[0057] This embodiment provides the application of the synchronous steering correction mechanism in controlling the synchronization of the drum steering and the tire steering of the vehicle to be tested.

[0058] When the wheel 10 is steered, the angle difference between the tire 10 steering and the drum 2 steering is obtained by converting and calculating the length change of the laser emitted by the distance measuring sensor 111 of the tire steering detection device 1 to the light curtain board 12, and the angle difference is fed back to the second driving assembly, which drives and controls the drum steering mechanism 3 to further rotate to correct the angle, so as to achieve the consistency of the drum 2 steering and the tire 10 steering.

[0059] Specifically, as Figure 5As shown, the light curtain board 12 is relatively stationary with the automobile tire and rotates with the tire turning, so the aforementioned angle difference is equal to the angle change of the light curtain board relative to itself, and this change can be calculated by the laser ranging length change L1', the laser ranging length change L2', and the laser spacing A, and the specific formula is: tire and hub turning angle difference = arctan(L1'+L2') / A, and the positive and negative and direction of L1' and L2' are defined, and the positive and negative and direction of the tire and hub turning angle difference can be obtained in turn.

[0060] Through the above process, the angle difference between the tire 10 turning and the hub 2 turning is fed back to the equipment control system, the reducer 8 controls the turning angle of the hub 2 in real time, so as to ensure that the hub 2 and the automobile tire 10 turning have high synchronization accuracy. Although the utility model has disclosed the above-mentioned preferred embodiments, it is not intended to limit the utility model, and any person skilled in the art can make various modifications and modifications without departing from the spirit and scope of the utility model, therefore, the protection scope of the utility model should be defined by the claims.

Claims

1. A tire cornering detection device for a chassis dynamometer, characterized by, The application relates to a tire steering detection device. The device comprises a base fixed to a chassis dynamometer, distance sensors arranged on both sides of the base, a hub connecting module comprising an inner ring rotating disc and a plurality of rotating bolts distributed on the inner ring rotating disc, the rotating bolts being connected to the hub of a vehicle to be tested and the inner ring rotating disc rotating synchronously with the hub, and a steering following module comprising an outer ring disc, a universal connector and a buffer connecting piece connected in sequence, the rotating shaft of the inner ring rotating disc being assembled in the outer ring disc through a bearing, both sides of the outer ring disc being provided with light curtain plates, and the buffer connecting piece being assembled in the base. When the vehicle to be tested is steering, the outer ring disc drives the light curtain plates to rotate synchronously with the wheels, the distance sensors can emit laser light and the laser light can always reach the light curtain plates. The universal connector comprises a cross shaft, a first steering knuckle connected to the outer ring disc and a second steering knuckle connected to the buffer connecting piece, the cross shaft comprising two shaft bodies which are perpendicular to each other and are connected at the center, and the first steering knuckle and the second steering knuckle are respectively mounted on the two shaft bodies. The base comprises an L-shaped vertical plate and a fixing plate connecting the bottom of the vertical plate and the chassis dynamometer, the L-shaped vertical plate has at least one vertically arranged strip-shaped hole, the buffer connecting piece is mounted in the strip-shaped hole, and the distance sensors are mounted on both sides of the L-shaped vertical plate.

2. The tire turn detection apparatus according to claim 1, characterized by The buffer connecting piece comprises a buffer bolt penetrating through the strip-shaped hole, one end of the buffer bolt being connected to the universal connector and the other end of the buffer bolt penetrating out of the strip-shaped hole, and both sides of the assembly position of the buffer bolt and the strip-shaped hole being provided with buffer seats.

3. The tire turn detection apparatus according to claim 2, characterized by The side of the L-shaped vertical plate away from the wheels is provided with a plurality of positioning holes at different heights, a positioning bolt is arranged in each positioning hole, and the positioning bolt is connected to the buffer seat through a traction spring.

4. The tire turn detection apparatus according to claim 3, characterized by The buffer seat has an arc-shaped contact surface which abuts against the two side surfaces of the L-shaped vertical plate.

5. The tire turn detection apparatus of claim 4, wherein The part of the buffer bolt between the universal connector and the L-shaped vertical plate is sleeved with an inside spring, and the part of the buffer bolt penetrating out of the strip-shaped hole is sleeved with an outside spring.

6. The tire turn detection apparatus of claim 5, wherein The application also relates to a tire steering detection device.

7. The tire turn detection apparatus of claim 6, wherein The device comprises a drum assembly in contact with the bottom of the wheel of a vehicle to be tested, the drum assembly being driven to operate by a first driving assembly, a drum steering mechanism bearing the drum assembly and connected to the tire steering detection device of any one of claims 1-7, and a rotating support mechanism arranged at the bottom of the drum steering mechanism and connected to a chassis dynamometer, the rotating support mechanism being driven to operate by a second driving assembly and being capable of carrying the drum steering mechanism and the drum assembly to rotate together, and the second driving assembly being capable of communicating with the distance sensors.

8. A synchronous steering correction mechanism for a chassis dynamometer, characterized by, The drum assembly comprises two drums arranged side by side, the wheel being located in a groove formed between the two drums and being in contact with the two drums, and the wheel being capable of rotating synchronously with the two drums. The first driving assembly comprises a drum driving motor mounted in the drum steering mechanism, a motor synchronous pulley connected to the drum driving motor and drum synchronous pulleys respectively mounted on the two drums, and the motor synchronous pulley being connected to the two drum synchronous pulleys through a synchronous belt. The second driving assembly comprises a steering driving motor mounted in the drum steering mechanism and a speed reducer connected to the steering driving motor, and the speed reducer being connected to a driving pinion. ​ 9. The synchronized steering correction mechanism of claim 8, wherein, ​ ​ ​ The rotary support mechanism comprises a ring gear connected to the bottom of the rotary drum steering mechanism, the ring gear is engaged with a driving pinion, and a rotation angle measuring mechanism is further arranged below the ring gear.

Images