A bearing ball process on-line inspection device

Abstract

A continuous inspection device for bearing ball bearings includes a turntable with multiple interconnected channels. These include a feed channel with a diameter larger than the acceptable ball size, connected internally to a negative deviation discharge channel with a diameter equal to the minimum negative deviation of the acceptable ball size; a non-deviation discharge channel with a diameter equal to the maximum positive deviation of the acceptable ball size; and a positive deviation discharge channel with a diameter larger than the maximum positive deviation of the acceptable ball size. The positive deviation discharge channel is located between the non-deviation discharge channel and the feed channel. The turntable is forced to rotate and has three stop positions, ensuring that any ball can flow out from its corresponding channel. This invention achieves high efficiency and reliable inspection results by setting multiple channels of different diameters within the turntable to inspect batches of balls individually. Pneumatic pressure ensures accurate entry of balls into their corresponding channels. The picking mechanism and drive structure are mechanically linked to ensure the individual selection and inspection of each ball.

Description

Technical Field

[0001] This invention relates to the field of ball bearing size inspection, and more specifically to a continuous inspection device for bearing ball bearing manufacturing processes. Background Technology

[0002] The manufacturing process of bearing inner balls typically includes cold forging, heat treatment, spherical grinding, cleaning and rust removal, and spherical surface quality inspection. Spherical grinding refers to the process of grinding the ball blank to achieve specified sphericity, dimensions, and surface quality. Spherical grinding usually uses specialized grinding machines with high-speed rotating grinding wheels to grind and polish the balls. Spherical surface quality inspection is performed after the ball manufacturing process to ensure that the ball's dimensions, shape, and surface quality meet requirements. Inspection items include ball diameter measurement, sphericity measurement, and surface roughness inspection.

[0003] The dimensions of bearing balls are very important because they directly affect bearing performance, load capacity, speed limits, accuracy and stability, friction and efficiency, lifespan, vibration and noise, installation and maintenance, and application adaptability. The dimensions of bearing balls have a critical impact on bearing performance and the performance of the entire mechanical system.

[0004] Therefore, ball bearings need to be sampled and inspected after manufacturing. The pass rate of the sampled ball bearings reflects the pass rate of the current batch, and deviations can be traced back to potential problems in the process. Current methods for inspecting ball bearing dimensions include: micrometer measurement, a common method suitable for small ball bearings, where the diameter of the ball bearing is directly measured using a micrometer or digital micrometer; optical measurement, which projects the image of the ball bearing onto a screen and measures its diameter using a calibrated scale; mechanical measurement, which uses a mechanical micrometer or other mechanical measuring equipment to measure its diameter by contact with the surface of the ball bearing, typically used for large ball bearings or applications requiring high precision; and ultrasonic measurement, which calculates the diameter by measuring the propagation time of sound waves on the ball bearing, a non-contact measurement method.

[0005] However, micrometers are neither efficient nor accurate. A certain percentage of balls must be sampled from each batch for the sampling results to be scientifically valid. Measuring a large number of balls with a micrometer is inefficient and the results cannot be guaranteed. Other measurement methods rely on expensive equipment, and each ball is inspected individually. Furthermore, regardless of the method, sampling is required, and none can be directly integrated into the manufacturing process for inspecting all balls, making them unsuitable for situations requiring extremely high pass rates and full ball inspection. Summary of the Invention

[0006] In response to the problems raised in the background art, the present invention provides a continuous detection device for the ball bearing process to solve these problems, and the present invention will be further described below.

[0007] A continuous inspection device for bearing ball bearings includes a turntable with multiple interconnected channels. The turntable includes a feed channel with a diameter larger than the acceptable ball size, penetrating the outer edge of the turntable and connected internally to a negative deviation discharge channel with a diameter equal to the minimum negative deviation of the acceptable ball size. The negative deviation discharge channel also penetrates the turntable, and the connection between the feed channel and the negative deviation discharge channel forms a cavity. The turntable also includes a non-deviation discharge channel with a diameter equal to the maximum positive deviation of the acceptable ball size, penetrating the turntable to the cavity. Additionally, the turntable includes a positive deviation discharge channel with a diameter larger than the maximum positive deviation of the acceptable ball size, penetrating the turntable to the cavity. The positive deviation discharge channel is located between the non-deviation discharge channel and the feed channel. The turntable is forced to rotate and has three stop positions, allowing any ball to flow out from its corresponding channel.

[0008] Preferably, the angle between the non-deviation discharge channel and the feed channel is an acute angle. This is intended to prevent balls with diameters within or outside the standard range from falling out of the negative deviation discharge channel after they are stuck at the inlet.

[0009] Preferably, the turntable rotates under the drive of a drive mechanism, which includes a crank, one end of which is pivotally connected to the output of a motor, and the other end of which is pivotally connected to a connecting rod. A rocker arm is pivotally connected to the center of the turntable, and the end of the rocker arm is pivotally connected to a positioning post on the turntable. The connecting rod is pivotally connected to the rocker arm.

[0010] Preferably, a sleeve is coaxially provided outside the turntable, and the turntable and the sleeve are fitted with a clearance. The sleeve is provided with a feed port, a negative deviation discharge port, a no deviation discharge port, and a positive deviation discharge port corresponding to the feed channel, the negative deviation discharge channel, the no deviation discharge channel, and the positive deviation discharge channel.

[0011] Preferably, the turntable is provided with a first air inlet, which is connected to the negative deviation discharge channel inside the turntable. By inflating the negative deviation discharge channel with air through the first air inlet, the balls are accelerated to leave the inlet position of the negative deviation discharge channel and roll towards the non-deviation discharge channel.

[0012] Preferably, the turntable is provided with a second air inlet, which is connected to the unbiased discharge channel inside the turntable. Air is injected and pressurized into the unbiased discharge channel through the second air inlet, accelerating the balls to leave the inlet position of the unbiased discharge channel and roll towards the positive deviation discharge channel.

[0013] Preferably, the feed inlet, negative deviation discharge outlet, no deviation discharge outlet, and positive deviation discharge outlet are respectively equipped with a feed sensor, a negative deviation discharge sensor, a no deviation discharge sensor, and a positive deviation discharge sensor; if any one of the negative deviation discharge sensor, the no deviation discharge sensor, and the positive deviation discharge sensor is triggered, the turntable will be reset.

[0014] Preferably, the sleeve has a material handling mechanism at the feed inlet, including a material cylinder, a chuck inside the material cylinder, the chuck having a slot that can only accommodate a single ball, the chuck being forced to rotate; there is a drain at the bottom of the material cylinder, and a slot on the cylinder wall as a channel for the ball to enter the material cylinder.

[0015] Preferably, the chuck is connected to a rotating shaft, and a gear is keyed to the rotating shaft. The gear meshes with a rack, which moves linearly in one direction under the action of a guide cylinder. A push rod is pivotally connected to the rack, and the other end of the push rod is pivotally connected to a crank. The interaction between the turntable and the chuck is determined mechanically, and there is only one driving source.

[0016] Beneficial effects: Compared with the prior art, the present invention performs one-by-one testing of a batch of balls by setting multiple channels of different diameters in the turntable, which is highly efficient and the testing results are reliable; the addition of pneumatic pressure ensures that the balls accurately enter the corresponding channels; at the same time, the material picking mechanism is linked with the drive structure, and the ball selection and testing are ensured one by one through mechanical structure linkage. Attached Figure Description

[0017] Figure 1 : A schematic diagram of the structure of this invention;

[0018] Figure 2 : Schematic diagram of the internal channel structure of the turntable;

[0019] Figure 3 : A diagram illustrating the rolling direction of smaller-than-standard balls within the turntable;

[0020] Figure 4 : A diagram showing the rolling direction of standard-sized balls within the turntable;

[0021] Figure 5 : A diagram illustrating the rolling direction of balls exceeding standard sizes within the turntable;

[0022] Figure 6 Top view of the material handling mechanism;

[0023] In the diagram: Turntable 1, Feed channel 101, Negative deviation discharge channel 102, Cavity 103, Non-deviation discharge channel 104, Positive deviation discharge channel 105, Crank 2, Motor 3, Connecting rod 4, Rocker arm 5, Positioning pin 6, Sleeve 7, Feed port 701, Negative deviation discharge port 702, Non-deviation discharge port 704, Positive deviation discharge port 705, First air inlet 8, Second air inlet 9, Feed sensor 10, Negative deviation discharge sensor 11, Non-deviation discharge sensor 12, Positive deviation discharge sensor 13, Material cylinder 14, Leak 1401, Groove 1402, Claw 15, Rotating shaft 16, Gear 17, Rack 18, Guide cylinder 19, Push rod 20. Detailed Implementation

[0024] Next, we will combine the appendix Figure 1-6 A specific embodiment of the present invention will be described in detail below.

[0025] Reference Appendix Figure 1-2 A continuous inspection device for bearing ball bearings is used to inspect the diameter of a large number of balls in a batch. The device includes a turntable 1 with multiple interconnected channels, including a feed channel 101. The diameter of the feed channel is greater than the maximum positive deviation of the qualified size of the ball, serving as the channel for the ball to enter the turntable.

[0026] Reference Appendix Figure 2 The feed channel 101 extends through the outer edge of the turntable, and one end of its interior is connected to a negative deviation discharge channel 102. The diameter of the negative deviation discharge channel 102 is equal to the minimum negative deviation of the qualified size of the ball, serving as an outlet channel for balls with insufficient diameter. The negative deviation discharge channel 102 extends through the turntable, and a cavity 103 is formed at the junction of the feed channel 101 and the negative deviation discharge channel 102 on the turntable 1.

[0027] The turntable 1 is also provided with a non-deviation discharge channel 104. The diameter of the non-deviation discharge channel 104 is equal to the maximum positive deviation of the qualified size of the ball. The non-deviation discharge channel 104 passes through the turntable to the cavity 103 and serves as the outflow channel for qualified balls of the correct diameter.

[0028] The turntable 1 is also provided with a positive deviation discharge channel 105. The diameter of the positive deviation discharge channel 105 is greater than the maximum value of the positive deviation of the qualified size of the ball. The positive deviation discharge channel 105 passes through the turntable to the cavity 103 and serves as the outflow channel for balls whose diameter exceeds the qualified range.

[0029] Reference Appendix Figure 2 The positive deviation discharge channel 105 is located between the non-deviation discharge channel 104 and the feed channel 101.

[0030] In general, the balls to be tested enter the turntable 1 one by one from the feed channel 101 until they fall into the cavity 103. If the diameter of the ball is smaller than the acceptable size range, the ball falls directly out of the turntable through the negative deviation discharge channel 102. If the diameter of the ball is within the acceptable size range, the ball falls directly from the cavity into the non-deviation discharge channel 104 and then out of the turntable. If the diameter of the ball exceeds the acceptable size range, the ball falls directly out of the turntable through the positive deviation discharge channel 105.

[0031] The turntable 1 rotates under the drive of the drive mechanism and has three stop positions, so that any ball can flow out from the corresponding flow channel, thus achieving the differentiation of the ball diameter. The system includes a negative deviation discharge position, where the negative deviation discharge channel is vertical. When the ball falls from the feed channel 101 into the cavity 103, if the ball diameter is smaller than the standard range, the ball directly enters the negative deviation discharge channel 102 and falls out of the turntable. If the ball diameter is within or exceeds the standard range, the ball directly remains in the cavity 103 and is stuck at the entrance of the negative deviation discharge channel 102. The system also includes a no-deviation discharge position, where the turntable 1 rotates to cause the ball stuck in the cavity 103 to leave the entrance of the negative deviation discharge channel 102 and roll towards the no-deviation discharge channel 104. If the ball diameter is within the standard range, the ball directly falls out of the turntable from the no-deviation discharge channel 104. If the ball exceeds the standard range, the ball is stuck at the entrance of the no-deviation discharge channel 104. The system also includes a positive deviation discharge position, where the turntable 1 rotates to cause the ball stuck at the entrance of the no-deviation discharge channel 104 to leave the no-deviation discharge channel and enter the positive deviation discharge channel 105 and fall out of the turntable.

[0032] The angle between the non-deviation discharge channel 104 and the feed channel 101 is an acute angle, which is intended to prevent balls with diameters within or outside the standard range from falling out of the negative deviation discharge channel 102 after they are stuck at the inlet of the negative deviation discharge channel 102.

[0033] Reference Appendix Figure 1 The turntable 1 rotates under the drive of the drive mechanism. This embodiment provides a preferred embodiment: the drive mechanism includes a crank 2, one end of which is pivotally connected to the output of a motor 3, and the other end is pivotally connected to a connecting rod 4. A rocker arm 5 is pivotally connected to the center of the turntable 1, and the end of the rocker arm 5 is pivotally connected to a positioning post 6 on the turntable. The connecting rod 4 is pivotally connected to the rocker arm 5. The crank 2 rotates with the motor 3, and the rocker arm reciprocates around the center of the turntable, causing the turntable to rotate clockwise and counterclockwise.

[0034] Reference Appendix Figure 2 A sleeve 7 is coaxially provided on the outside of the turntable 1. The turntable and the sleeve are fitted with a clearance. The sleeve 7 is provided with a feed port 701, a negative deviation discharge port 702, a no deviation discharge port 704, and a positive deviation discharge port 705 corresponding to the feed channel 101, the negative deviation discharge channel 102, the no deviation discharge channel 104, and the positive deviation discharge channel 105.

[0035] Reference Appendix Figure 1The turntable is equipped with a first air inlet 8, which connects to the negative deviation discharge channel 102 inside the turntable. Its function is as follows: if the diameter of the ball is within or exceeds the standard range, the ball will be stuck at the entrance of the negative deviation discharge channel 102. Then, the turntable 1 rotates until the non-deviation discharge channel 104 is directly opposite the non-deviation discharge port 704. At this point, the negative deviation discharge port 702 is sealed by the sleeve 7. Air is then pressurized into the negative deviation discharge channel 102 through the first air inlet 8, accelerating the ball to leave the entrance position of the negative deviation discharge channel 102 and roll towards the non-deviation discharge channel 104. If the diameter of the ball is within the standard range, the ball will fall directly out of the turntable from the non-deviation discharge channel 104; if the ball exceeds the standard range, the ball will be stuck at the entrance of the non-deviation discharge channel 104.

[0036] The turntable is provided with a second air inlet 9, which is connected to the non-deviation discharge channel 104 inside the turntable. Its function is as follows: when the ball exceeds the standard range, the ball is stuck at the entrance of the non-deviation discharge channel 104. Then the turntable 1 rotates until the positive deviation discharge channel 105 is directly opposite the positive deviation discharge port 705. At this time, the non-deviation discharge port 704 is closed by the sleeve 7. Air is injected into the non-deviation discharge channel 104 through the second air inlet 9 to increase the pressure, which accelerates the ball to leave the entrance position of the non-deviation discharge channel 104 and roll towards the positive deviation discharge channel 105.

[0037] Reference Appendix Figure 2 The feed inlet 701, the negative deviation discharge outlet 702, the non-deviation discharge outlet 704, and the positive deviation discharge outlet 705 are respectively equipped with a feed sensor 10, a negative deviation discharge sensor 11, a non-deviation discharge sensor 12, and a positive deviation discharge sensor 13.

[0038] When the ball passes through the feed inlet 701, the feed sensor 10 is triggered to start a timer. If the ball diameter is below the standard range, it falls directly out of the turntable through the negative deviation discharge channel 102, triggering the negative deviation discharge sensor 11. The turntable is driven by the drive mechanism to rotate one cycle and then reset, the timer is cleared, and it is ready to be triggered by the next ball. If the ball diameter reaches or exceeds the standard range, the negative deviation discharge sensor 11 cannot be triggered within a predetermined time. At this time, the trigger drive mechanism drives the turntable to rotate to the non-deviation discharge channel 104, which is directly opposite the non-deviation discharge inlet 704, opening the pneumatic passage and allowing the first air intake. Air is pressurized into the negative deviation discharge channel 102 through port 8. If the diameter of the ball is qualified, it falls directly out of the turntable through the non-deviation discharge channel 104 and triggers the non-deviation discharge sensor 12, causing the turntable to reset. If the non-deviation discharge sensor 12 is not triggered within a predetermined time, the drive mechanism is triggered to drive the turntable to rotate to the positive deviation discharge channel 105, which is directly opposite the positive deviation discharge port 705. The pneumatic passage is opened to pressurize the non-deviation discharge channel 104 through the second air inlet 9, so that the ball enters the positive deviation discharge channel 105 and falls out of the turntable, triggering the positive deviation discharge sensor 13 to reset the turntable.

[0039] It should be noted that when any one of the negative deviation discharge sensor 11, the non-deviation discharge sensor 12, and the positive deviation discharge sensor 13 is triggered, the turntable 1 will rotate for a complete cycle. Moreover, the turntable does not rotate in one direction, but rotates clockwise and counterclockwise under the drive mechanism to avoid the airflow pipe from getting tangled.

[0040] Reference Appendix Figure 1 and 6 In this invention, the balls enter the turntable one by one. To achieve the feeding of the balls one by one, this embodiment provides a feeding mechanism on the feed port 701 of the sleeve 7, including a material cylinder 14. A chuck 15 is provided inside the material cylinder. The chuck has a slot that can only accommodate a single ball. The chuck is forced to rotate. There is a drain 1401 at the bottom of the material cylinder 14 and a slot 1402 on the cylinder wall. The slot serves as a channel for the balls to enter the material cylinder and as a channel for the balls to enter the turntable below.

[0041] In this embodiment, in order to achieve synchronous cooperation between the material handling mechanism and the turntable, the chuck 15 is rotated under the drive of the crank 2 through mechanical linkage. The specific solution is as follows: the chuck is connected to the rotating shaft 16, and a gear 17 is keyed to the rotating shaft. The gear 17 meshes with a rack 18, and the rack 18 moves linearly in one direction under the action of the guide cylinder 19. A push rod 20 is pivotally connected to the rack 18, and the other end of the push rod 20 is pivotally connected to the crank 2.

[0042] During the rotation of crank 2, it drives turntable 1 to rotate on one hand and chuck 15 to rotate on the other. The mechanical mechanism determines the interaction between the turntable and chuck, and there is only one driving source.

[0043] Reference Appendix Figure 3-5 In this embodiment, the present invention provides a detection method for a continuous bearing ball detection device, comprising the following steps:

[0044] Initial position calibration: the ball falls from the drain 1401 at the bottom of the barrel 14 into the turntable 1. During the falling process, the feed sensor 10 is triggered, and the timing is triggered. The ball falls from the feed channel 101 into the cavity 103.

[0045] If the diameter of the ball is below the standard range, it will fall directly out of the turntable through the negative deviation discharge channel 102 and trigger the negative deviation discharge sensor 11. The timer will be reset, and the turntable will rotate one cycle under the drive mechanism to reset. At the same time, the drive mechanism will rotate the chuck 15 to select the next ball and transport it to the turntable; otherwise, proceed to the next step.

[0046] If the diameter of the ball reaches or exceeds the standard range, and the negative deviation discharge sensor 11 is not triggered within a predetermined time, the drive mechanism is triggered to rotate the turntable to the non-deviation discharge channel 104 facing the non-deviation discharge port 704, and the pneumatic passage is opened to pressurize the negative deviation discharge channel 102 through the first air inlet 8; if the ball falls directly out of the turntable from the non-deviation discharge channel 104 and triggers the non-deviation discharge sensor 12, causing the turntable to reset, the diameter of the ball is determined to be qualified; otherwise, if the non-deviation discharge sensor 12 is not triggered within a predetermined time, proceed to the next step.

[0047] The trigger drive mechanism drives the turntable to rotate until the positive deviation discharge channel 105 is directly opposite the positive deviation discharge port 705. The pneumatic passage is opened and air is pressurized into the non-deviation discharge channel 104 through the second air inlet 9, causing the balls to enter the positive deviation discharge channel 105 and fall out of the turntable. The positive deviation discharge sensor 13 is then triggered to reset the turntable.

[0048] This invention achieves high efficiency and reliable testing results by setting multiple channels of different diameters within the turntable to inspect batches of balls one by one. Pneumatic pressure is added to ensure that the balls accurately enter the corresponding channels. At the same time, the material handling mechanism is linked with the drive structure, and the selection and inspection of the balls are ensured through mechanical linkage.

[0049] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A process-continuous bearing ball inspection apparatus, characterized by: The turntable (1) includes multiple interconnected channels, including a feed channel (101) with a diameter larger than the qualified size of the ball bearings. The feed channel passes through the outer edge of the turntable and is connected to a negative deviation discharge channel (102) with a diameter equal to the minimum negative deviation of the qualified size of the ball bearings. The negative deviation discharge channel also passes through the turntable. The connection between the feed channel (101) and the negative deviation discharge channel (102) forms a cavity (103). The turntable (1) also includes a channel with a diameter equal to the maximum positive deviation of the qualified size of the ball bearings. The unbiased discharge channel (104) extends through the turntable to the cavity (103); the turntable (1) is also provided with a positive deviation discharge channel (105) with a diameter greater than the maximum positive deviation of the qualified size of the ball, which extends through the turntable to the cavity (103); the positive deviation discharge channel (105) is located between the unbiased discharge channel (104) and the feed channel (101), the turntable (1) is forced to rotate and has three stop positions, so that any ball can flow out from the corresponding flow channel; The angle between the unbiased discharge channel (104) and the feed channel (101) is an acute angle; The turntable (1) rotates under the drive of the drive mechanism, which includes a crank (2), one end of which is pivotally connected to the output of the motor (3), and the other end is pivotally connected to a connecting rod (4). A rocker arm (5) is pivotally connected to the center of the turntable (1), and the end of the rocker arm (5) is pivotally connected to a positioning post (6) on the turntable. The connecting rod (4) is pivotally connected to the rocker arm (5). A sleeve (7) is coaxially provided on the outside of the turntable (1). The turntable and the sleeve are in clearance fit. The sleeve (7) is provided with a feed port (701), a negative deviation discharge port (702), a non-deviation discharge port (704), and a positive deviation discharge port (705) corresponding to the feed channel (101), the negative deviation discharge channel (102), the non-deviation discharge channel (104), and the positive deviation discharge channel (105). The turntable is provided with a first air inlet (8), which is connected to the negative deviation discharge channel (102) inside the turntable; the turntable is provided with a second air inlet (9), which is connected to the non-deviation discharge channel (104) inside the turntable. The feed inlet (701), negative deviation discharge outlet (702), no deviation discharge outlet (704), and positive deviation discharge outlet (705) are respectively equipped with a feed sensor (10), a negative deviation discharge sensor (11), a no deviation discharge sensor (12), and a positive deviation discharge sensor (13). When the ball passes through the feed inlet, the feed sensor is triggered and a timer is started. If the ball diameter is below the standard range, it falls directly out of the turntable through the negative deviation discharge channel, triggering the negative deviation discharge sensor. The turntable is then driven by the drive mechanism to rotate one cycle and reset, the timer is cleared, and it is ready to be triggered by the next ball. If the ball diameter reaches or exceeds the standard range, the negative deviation discharge sensor cannot be triggered within the predetermined time. At this time, the drive mechanism is activated to rotate the turntable until it is aligned with the zero deviation discharge channel, opening the pneumatic passage for passage. The first air inlet pressurizes the negative deviation discharge channel. If the diameter of the ball is within acceptable limits, it falls directly out of the turntable through the non-deviation discharge channel and triggers the non-deviation discharge sensor, causing the turntable to reset. If the non-deviation discharge sensor is not triggered within a predetermined time, the drive mechanism is activated to rotate the turntable to face the positive deviation discharge port. The pneumatic passage is then opened to pressurize the non-deviation discharge channel through the second air inlet, causing the ball to enter the positive deviation discharge channel and fall out of the turntable, triggering the positive deviation discharge sensor and causing the turntable to reset.

2. The continuous detection device for bearing ball bearing process according to claim 1, characterized in that: The sleeve (7) has a feeding port (701) with a material picking mechanism, including a material cylinder (14), a chuck (15) inside the material cylinder, the chuck having a slot that can only accommodate a single ball, the chuck being forced to rotate; there is a drain (1401) at the bottom of the material cylinder (14), and a slot (1402) on the cylinder wall, which serves as a channel for the ball to enter the material cylinder.

3. The continuous detection device for bearing ball bearing process according to claim 2, characterized in that: The pawl is connected to the rotating shaft (16), and a gear (17) is keyed to the rotating shaft. The gear (17) meshes with a rack (18), and the rack (18) moves linearly in one direction under the action of the guide cylinder (19). A push rod (20) is pivotally connected to the rack (18), and the other end of the push rod (20) is pivotally connected to the crank (2). The interaction between the turntable and the pawl is determined mechanically, and there is only one driving source.

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