A dynamic test device for the performance of automotive motors

Abstract

The present invention discloses a device for dynamically testing the performance of an automobile motor, comprising a base, a fixing mechanism, a shaking mechanism, a connecting mechanism and a humidifying mechanism, wherein a performance testing device is fixedly connected to the base, a slide groove is provided on the base, a scene simulation box is slidably connected in the slide groove, the fixing mechanism is used for installing and testing a motor to be tested, the shaking mechanism is used for shaking the fixing mechanism to simulate the performance stability of the motor under shaking, the connecting mechanism is used for transmitting the rotation data of the motor output end during the shaking process to the input end of the performance testing device, and the humidifying mechanism is used for linking the shaking mechanism to perform humidification simulation in the scene simulation box when the shaking mechanism is running. The device for dynamically testing the performance of an automobile motor solves the problems that the existing dynamic testing device for the performance of an automobile motor is difficult to detect the performance of the motor during the shaking process and the shaking of the equipment affects the service life, and is convenient for people to use.

Description

Technical Field

[0001] The invention relates to the technical field of motor performance testing, in particular to a vehicle motor performance dynamic testing device. Background Art

[0002] As the popularity of new energy vehicles expands, the use environment of new energy vehicles is becoming increasingly complex. Vehicles will work in harsh environments such as high temperature, high humidity, and high cold. The performance of the motor in this environment directly affects the safety, power, and economy of the vehicle. For example, the problem of abnormal noise at low temperature of the motor directly affects the user's satisfaction; the problem of demagnetization at high temperature of the motor will cause the vehicle's power to deteriorate; the insulation problem of the motor under high humidity conditions will directly affect the vehicle's driving safety. Therefore, all new energy vehicle OEMs and suppliers have invested a lot of resources in motor environmental testing.

[0003] The speed of motors used in new energy vehicles generally exceeds 10,000 rpm, and the torque is above 200 Nm. The high-speed and high-dynamic operating conditions put forward higher requirements for the environmental test system, which not only needs to provide environmental conditions for the motor, but also needs to ensure the high centering accuracy of the motor. Therefore, it is inevitable to develop a rapid environmental test system for automotive motors with high centering accuracy, fast replacement speed, good sealing, and bearing environmental adaptability.

[0004] Some of the existing dynamic test devices for automobile motor performance are capable of testing the working performance of motors in harsh environments such as high temperature, high humidity, and high cold. However, on some bumpy roads, frequent shaking will also affect the performance of the motor, especially for some low-end cars with poor shock absorption. Long-term shaking of the motor will reduce the service life of the motor. There are few existing test devices with this aspect. At the same time, some shaking test devices require the detection equipment to be shaken together, which will affect the service life of the equipment in the long run. To this end, we propose a dynamic test device for automobile motor performance. Summary of the invention

[0005] The purpose of the present invention is to provide a vehicle motor performance dynamic testing device that is convenient for testing the motor performance during the motor shaking process, so as to solve the problems raised in the above background technology.

[0006] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a dynamic testing device for automobile motor performance, comprising a base, a fixing mechanism, a shaking mechanism, a connecting mechanism and a humidifying mechanism, wherein a performance testing device is fixedly connected to the base, a mounting frame is fixedly connected to the base, a slide groove is provided on the base, a scene simulation box is slidably connected in the slide groove, the fixing mechanism is installed on the base, and is used to install and test the motor to be tested, the shaking mechanism is installed on the base, and is used to shake the fixing mechanism to simulate the performance stability of the motor under shaking, and the connecting mechanism is installed on the performance testing device, and is used to transmit the rotation data of the motor output end during the shaking process to the performance testing device. The input end of the detection equipment, the humidifying mechanism is installed in the scene simulation box, and is used to link the humidification simulation in the scene simulation box when the shaking mechanism is running. The device is convenient for testing the performance of the motor during shaking by setting a shaking mechanism and a connecting mechanism, and at the same time, the output end of the shaking motor can be rotated and stably transmitted to the input end of a performance detection device fixed on the base. The device is convenient for triggering the operation of the humidifying mechanism by the amplitude of the shaking when the shaking mechanism is working, so that the humidifying mechanism can continuously humidify the motor to detect the performance of the motor under high humidity conditions. The device is simple and quick to operate, improves the detection efficiency, makes the detection more comprehensive, and is convenient for people to use.

[0007] Preferably, the fixing mechanism includes two first side plates fixedly mounted on the base, a first spring fixedly connected to the first side plate, a shaking block slidably connected to the base fixedly connected to the first spring, a second spring fixedly connected to the top of the shaking block, a mounting plate fixedly connected to the second spring, second side plates slidably connected to the mounting plate fixedly connected to both sides of the shaking block, a sliding block slidably connected to the mounting plate, a limiting member for limiting the position of the sliding block is provided on the sliding block, so as to facilitate fixing the motor under test on the equipment for testing.

[0008] Preferably, the connecting mechanism includes a first gear column fixedly connected to the output end of the motor to be tested, the first gear column is plugged with a first disc, the first disc is provided with a first gear groove, the base is fixedly connected to a fixing frame, the fixing frame is fixedly connected to a first ring, the first ring is provided with a transmission part for transmission, so as to facilitate the stable transmission of the output power of the motor during the shaking process to the input end of the performance detection equipment fixed on the base.

[0009] Preferably, the transmission member includes a plurality of third springs fixedly installed on the inner wall of the first ring and fixedly connected thereto. The plurality of third springs are fixedly connected to a second ring. The inner wall of the second ring is rotatably connected to a second disc. A second gear groove is formed in the second disc. The input end of the performance detection device is fixedly connected to a first gear, and the second disc is coaxially fixedly connected to a second gear.

[0010] Preferably, the jitter mechanism includes a motor mount fixedly installed in the scene simulation box. A motor is fixedly installed on the motor mount. The output end of the motor is fixedly connected to a second gear column. An internal gear tube inserted with the second gear column is rotatably connected to the mounting frame. A plurality of cams are fixedly connected to the internal gear tube. The shaking block is provided with a first inclined surface and a second inclined surface, which are convenient for driving the motor to jitter in the horizontal and vertical directions.

[0011] Preferably, the limiting member includes a stopper fixedly installed on the sliding block. A fourth spring is fixedly connected to the stopper. The fourth spring is fixedly connected to a plug block slidably connected to the stopper. A plurality of helical tooth grooves inserted with the plug block are formed on the mounting plate, which is convenient for fixing the motor.

[0012] Preferably, the humidifying mechanism includes two water tanks fixedly installed in the scene simulation box. A plurality of atomizing nozzles are provided on the two water tanks. A one-way valve for adding water to the water tank and having a one-way air intake function is threadedly connected to the scene simulation box. A humidifying member for driving the atomizing nozzles to spray water when the mounting plate shakes is provided in the scene simulation box, which is convenient for simulating a high-humidity environment in the scene simulation box.

[0013] Preferably, the humidifying member includes a fifth spring fixedly installed in the scene simulation box. A push plate is fixedly connected to the fifth spring. A water spraying button is provided on the water tank. Third inclined surfaces slidably connected to the water spraying button are formed at both ends of the push plate, which is convenient for driving the atomizing nozzles to spray water mist by the shaking of the mounting plate.

[0014] Preferably, the first disc, the second disc, the first gear and the second gear are all made of high-strength impact-resistant alloy material, which is more durable and prolongs the service life of the equipment.

[0015] Compared with the prior art, the beneficial effects of the present invention are:

[0016] The present invention solves the problems that it is difficult to detect the performance of an automotive motor during the jitter process when using an existing dynamic test device for automotive motor performance, and the jitter of the device affects its service life. By setting up a jitter mechanism and a connection mechanism, the device facilitates the testing of the performance of the motor during the jitter process. At the same time, the rotating output end of the jittering motor can be stably transmitted to the input end of a performance detection device fixed on the base. By setting up a humidifying mechanism, it is convenient to continuously trigger the operation of the humidifying mechanism using the amplitude of the jitter when the jitter mechanism is working, so that the humidifying mechanism can continuously humidify the motor to detect the performance of the motor under high humidity conditions. The device is simple and fast to operate, improves the detection efficiency, makes the detection more comprehensive, and is convenient for people to use. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic diagram of the overall structure of the present invention;

[0018] Figure 2 is a schematic diagram of the internal structure of the present invention;

[0019] Figure 3 is a schematic diagram of a partial structure of the connection mechanism of the present invention;

[0020] Figure 4 is Figure 3 an enlarged view of area A in

[0021] Figure 5 is a schematic diagram of a partial structure of the humidifying mechanism of the present invention;

[0022] Figure 6 is Figure 5 an enlarged view of area B in

[0023] Figure 7 is Figure 5 an enlarged view of area C in

[0024] Figure 8 is a schematic diagram of a partial structure of the jitter mechanism of the present invention;

[0025] Figure 9 is a schematic diagram of a partial structure of the fixing mechanism of the present invention;

[0026] Figure 10 is Figure 9 an enlarged view of area D in

[0027] In the figure: 1-base; 2-performance testing equipment; 3-mounting frame; 4-slide; 5-scene simulation box; 6-fixing mechanism; 7-shaking mechanism; 8-connecting mechanism; 9-humidifying mechanism; 10-first side plate; 11-first spring; 12-shaking block; 13-second spring; 14-mounting plate; 15-second side plate; 16-sliding block; 17-limiting member; 18-first gear column; 19-first disc; 20-first gear slot; 21-fixing frame; 22-first ring; 23-third spring; 24-second ring ; 25-second disc; 26-second gear groove; 27-first gear; 28-second gear; 29-motor frame; 30-motor; 31-second gear column; 32-inner gear tube; 33-cam; 34-first inclined plane; 35-second inclined plane; 36-stopper; 37-fourth spring; 38-plug-in block; 39-oblique tooth groove; 40-water tank; 41-atomizing nozzle; 42-one-way valve; 43-humidifying element; 44-fifth spring; 45-push plate; 46-water spray button; 47-third inclined plane; 48-transmission member. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] Example 1

[0030] See also Figures 1 - 4 A dynamic test device for automobile motor performance shown in the figure includes a base 1, a fixing mechanism 6, a shaking mechanism 7, a connecting mechanism 8 and a humidifying mechanism 9. A performance detection device 2 is fixedly connected to the base 1, a mounting frame 3 is fixedly connected to the base 1, a slide groove 4 is provided on the base 1, and a scene simulation box 5 is slidably connected in the slide groove 4. The fixing mechanism 6 is installed on the base 1 for installing and testing the motor to be tested. The shaking mechanism 7 is installed on the base 1 for shaking the fixing mechanism 6 to simulate the performance stability of the motor under shaking. The connecting mechanism 8 is installed on the performance detection device 2 for transmitting the rotation data of the motor output end during the shaking process to the input end of the performance detection device 2. The humidifying mechanism 9 is installed in the scene simulation box 5 for humidifying the scene simulation box 5 when the shaking mechanism 7 is running.

[0031] See also Figures 5 - 10, the fixing mechanism 6 in the figure includes two first side plates 10 fixedly installed on the base 1. A first spring 11 is fixedly connected to the first side plate 10. The first spring 11 is fixedly connected to a swaying block 12 slidably connected to the base 1. The top of the swaying block 12 is fixedly connected to a second spring 13. The second spring 13 is fixedly connected to a mounting plate 14. Both sides of the swaying block 12 are fixedly connected to second side plates 15 slidably connected to the mounting plate 14. A sliding block 16 is slidably connected to the mounting plate 14. A limiting member 17 for limiting the position of the sliding block 16 is provided on the sliding block 16.

[0032] Please refer to Figures 3 - 7 , the connecting mechanism 8 in the figure includes a first gear column 18 fixedly connected to the output end of the motor to be tested. The first gear column 18 is inserted into a first disc 19. A first gear groove 20 is formed in the first disc 19. A fixing frame 21 is fixedly connected to the base 1. A first ring 22 is fixedly connected to the fixing frame 21. A transmission member 48 for transmission is provided on the first ring 22.

[0033] Please refer to Figures 3 - 7 , the transmission member 48 in the figure includes multiple groups of third springs 23 fixedly installed and fixedly connected to the inner wall of the first ring 22. The multiple groups of third springs 23 are fixedly connected to a second ring 24. The inner wall of the second ring 24 is rotatably connected to a second disc 25. A second gear groove 26 is formed in the second disc 25. The input end of the performance detection device 2 is fixedly connected to a first gear 27. The second disc 25 is coaxially fixedly connected to a second gear 28. The first disc 19, the second disc 25, the first gear 27, and the second gear 28 are all made of high-strength impact-resistant alloy material.

[0034] In this embodiment, slide open the scene simulation box 5, place the motor to be tested on the mounting plate 14, slide the sliding block 16 to clamp the motor, fix the sliding block 16 by the limiter 17, so that the first gear column 18 at the output end of the motor is plugged and fixed with the first disc 19, close the scene simulation box 5, start the motor, and start the shaking mechanism 7 at the same time. The shaking mechanism 7 drives the shaking block 12 to shake left and right and drives the mounting plate 14 to shake up and down, so that the motor shakes up and down. At this time, the motor drives the first disc 19 to rotate. The first disc 19 drives the first gear slot 20 to rotate. The outer diameter of the second gear 28 is slightly smaller than the inner diameter of the first gear slot 20, so that the first gear slot 20 can continuously drive the second gear 28 to rotate. At the same time, the first disc 19 can shake to a certain extent, and the second gear 28 will always be rotated by the first gear slot 20. At the same time, The second gear 28 drives the second disc 25 to rotate. The second disc 25 can rotate and at the same time can shake to a certain extent under the action of the second ring 24 and the third spring 23. The rotation of the second disc 25 drives the second gear slot 26 and the first gear 27 to rotate. The outer diameter of the first gear 27 is slightly smaller than the inner diameter of the second gear slot 26, so that the second gear slot 26 can continuously drive the first gear 27 to rotate while the second disc 25 can shake to a certain extent. In this way, the motor can stably transmit the rotation of the output end to the input end of the performance testing device 2 while constantly shaking. At the same time, the performance testing device 2 will not shake, thereby avoiding the long-term shaking that affects the service life of the performance testing device 2. At the same time, the mounting plate 14 will drive the humidification mechanism 9 to continuously spray water mist in the scene simulation box 5 while shaking, thereby jointly simulating a high humidity environment.

[0035] Example 2

[0036] See also Figures 5 - 10 Embodiment 2 is described. This embodiment further describes Embodiment 1. The shaking mechanism 7 shown in the figure includes a motor frame 29 fixedly mounted in the scene simulation box 5. A motor 30 is fixedly mounted on the motor frame 29. The output end of the motor 30 is fixedly connected to a second gear column 31. An internal gear tube 32 that is plugged into the second gear column 31 is rotatably connected to the mounting frame 3. A plurality of cams 33 are fixedly connected to the internal gear tube 32. A first inclined surface 34 and a second inclined surface 35 are provided on the shaking block 12.

[0037] See also Figures 9 - 10 The limiting member 17 shown in the figure includes a stopper 36 fixedly mounted on the sliding block 16, to which a fourth spring 37 is fixedly connected, and the fourth spring 37 is fixedly connected to a plug-in block 38 slidably connected to the stopper 36, and a plurality of groups of oblique tooth grooves 39 plugged into the plug-in block 38 are provided on the mounting plate 14.

[0038] In this embodiment, the model of the motor 30 is preferably YYHS-40. When the scene simulation box 5 is pulling the switch, the second gear column 31 is always plugged into the inner gear tube 32, ensuring that the transmission between the motor 30 and the inner gear tube 32 will not be disconnected. When the motor 30 is started, the motor 30 drives the second gear column 31 to rotate, thereby driving the inner gear tube 32 to rotate, and the cam 33 can be driven to rotate. When the cam 33 hits the bottom surface of the mounting plate 14, it pushes the mounting plate 14 to move up, the second spring 13 is stretched, and the cam 33 continues to rotate and hits the first inclined surface 34 to push the shaking block 12 moves to compress the first spring 11 on that side, and then the cam 33 rotates and hits the second inclined surface 35 to push the shaking block 12 to move to the other side to compress the first spring 11 on that side. Thereafter, the cam 33 continues to hit the bottom surface of the mounting plate 14. This reciprocating process can realize the horizontal and vertical shaking of the motor. The plug-in block 38 is pushed upward to compress the fourth spring 37 to release the plug-in block 38 from the oblique tooth groove 39, and the sliding block 16 can be slid to release the fixation of the motor. The sliding block 16 is provided with a fixing ring (not shown) for clamping the upper and lower ends of the motor to prevent the motor from shaking upward when it shakes.

[0039] Example 3

[0040] See also Figures 1 - 4 The figure includes a base 1, a fixing mechanism 6, a shaking mechanism 7, a connecting mechanism 8 and a humidifying mechanism 9. A performance testing device 2 is fixedly connected to the base 1. A mounting frame 3 is fixedly connected to the base 1. A slide groove 4 is provided on the base 1. A scene simulation box 5 is slidably connected in the slide groove 4. The fixing mechanism 6 is installed on the base 1 for installing and testing the motor to be tested. The shaking mechanism 7 is installed on the base 1 for shaking the fixing mechanism 6 to simulate the performance stability of the motor under shaking. The connecting mechanism 8 is installed on the performance testing device 2 for transmitting the rotation data of the motor output end during the shaking process to the input end of the performance testing device 2. The humidifying mechanism 9 is installed in the scene simulation box 5 for humidifying the scene simulation box 5 when the shaking mechanism 7 is running.

[0041] See also Figures 5 - 7 Embodiment 3 is described. This embodiment further describes Embodiment 1. The humidifying mechanism 9 shown in the figure includes two water tanks 40 fixedly installed in the scene simulation box 5. The two water tanks 40 are provided with multiple groups of atomizing nozzles 41. A one-way valve 42 for adding water to the water tank 40 and having a one-way air intake function is threadedly connected to the scene simulation box 5. A humidifying component 43 is provided in the scene simulation box 5 for linking the atomizing nozzle 41 to spray water when the mounting plate 14 shakes.

[0042] See also Figures 5 - 7, in the illustrated diagram, the humidifying member 43 includes a fifth spring 44 fixedly installed in the scene simulation box 5. A push plate 45 is fixedly connected to the fifth spring 44. A water spraying button 46 is provided on the water tank 40. Third inclined surfaces 47 for slidably connecting with the water spraying button 46 are formed at both ends of the push plate 45.

[0043] In this implementation, slide the scene simulation box 5 to one side of the mounting frame 3 to form a relatively sealed environment. Start the motor 30 to drive the mounting plate 14 to shake. The mounting plate 14 will continuously push the push plate 45 to move up and down. When the push plate 45 moves up to compress the fifth spring 44, the third inclined surface 47 will toggle the water spraying button 46 to spray the water in the water tank 40 from the atomizing nozzle 41. At this time, the one-way valve 42 can only let air in and not out to ensure the air pressure balance inside the water tank 40. Opening the one-way valve 42 can add water to the water tank 40. This device does not require other motors to drive. Only during the process of starting the motor 30 to drive the motor to shake, the force of the motor shaking is used to continuously trigger the water spraying button 46, saving energy.

[0044] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device.

[0045] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A dynamic test device for automobile motor performance, characterized in that: include: A base (1), a performance detection device (2) is fixedly connected to the base (1), a mounting frame (3) is fixedly connected to the base (1), a slide groove (4) is provided on the base (1), and a scene simulation box (5) is slidably connected in the slide groove (4); Also includes: A fixing mechanism (6), the fixing mechanism (6) comprising a shaking block (12) connected to the base (1) in a horizontal sliding direction, a second spring (13) fixedly connected to the top end of the shaking block (12), a mounting plate (14) fixedly connected to the upper end of the second spring (13), and used for fixing motors to be tested of different sizes on the mounting plate (14) for dynamic testing; A shaking mechanism (7), the shaking mechanism (7) comprising a plurality of cams (33) mounted on the base (1), and used to impact and shake the shaking block (12) through the cams (33), thereby causing the motor to be tested to shake in multiple directions, simulating the performance stability of the motor under shaking; A connecting mechanism (8), the connecting mechanism (8) being mounted on the performance detection device (2) and used for transmitting rotation data of the motor output end during the shaking process to the input end of the performance detection device (2); A humidifying mechanism (9), wherein the humidifying mechanism (9) comprises two water tanks (40) fixedly mounted in the scene simulation box (5), and is used to link the water tanks (40) to spray water in parallel when the shaking mechanism (7) is in operation, so as to simulate humidification in the scene simulation box (5); the connecting mechanism (8) comprises a first gear column (18) fixedly connected to the output end of the motor to be tested, the first gear column (18) being plugged with a first disc (19), the first disc (19) being provided with a first gear groove (20), the base (1) being fixedly connected with a fixing frame (21), the fixing frame (21) being fixedly connected with a first ring (22), the first ring (22) being provided with a transmission member (48) for dynamic transmission, the transmission member (48) comprising a plurality of groups of third springs (23) fixedly mounted on the inner wall of the first ring (22), the plurality of groups of the third springs being connected to the inner wall of the first ring (22). (23) is fixedly connected to a second ring (24), the inner wall of the second ring (24) is rotatably connected to a second disk (25), a second gear groove (26) is provided in the second disk (25), the input end of the performance detection device (2) is fixedly connected to a first gear (27), the second disk (25) is coaxially fixedly connected to a second gear (28), the shaking mechanism (7) comprises a motor frame (29) fixedly mounted in the scene simulation box (5), a motor (30) is fixedly mounted on the motor frame (29), the output end of the motor (30) is fixedly connected to a second gear column (31), the mounting frame (3) is rotatably connected to an internal gear tube (32) plugged into the second gear column (31), a plurality of groups of cams (33) are fixedly mounted on the internal gear tube (32), and the shaking block (12) is provided with a first inclined surface (34) and a second inclined surface (35).

2. The automotive motor performance dynamic testing device according to claim 1 is characterized in that: The fixing mechanism (6) further comprises two first side plates (10) fixedly mounted on the base (1), the first side plates (10) being fixedly connected to a first spring (11), one end of the first spring (11) being fixedly connected to the shaking block (12), the two sides of the shaking block (12) being fixedly connected to second side plates (15) slidably connected to the mounting plate (14), the mounting plate (14) being slidably connected to a sliding block (16) in a horizontal direction, the sliding block (16) being provided with a limiting member (17) for limiting position.

3. The automotive motor performance dynamic testing device according to claim 2 is characterized in that: The limiting member (17) comprises a stopper (36) fixedly mounted on the sliding block (16), a fourth spring (37) fixedly connected to the stopper (36), a plug-in block (38) slidably connected to the fourth spring (37), and a plurality of groups of oblique tooth grooves (39) plugged into the plug-in block (38) are provided on the mounting plate (14).

4. The automotive motor performance dynamic testing device according to claim 1 is characterized in that: The humidifying mechanism (9) comprises a plurality of groups of atomizing nozzles (41) respectively mounted on the water tanks (40) on both sides; a one-way valve (42) for adding water to the water tank (40) and having a one-way air intake function is threadedly connected to the scene simulation box (5); a humidifying component (43) is provided in the scene simulation box (5) for linking the atomizing nozzles (41) to spray water when the mounting plate (14) is shaken.

5. The automotive motor performance dynamic testing device according to claim 4 is characterized in that: The humidifying element (43) comprises a fifth spring (44) fixedly mounted in the scene simulation box (5), a push plate (45) being fixedly connected to the fifth spring (44), a water spray button (46) being provided on the water tank (40), and third inclined surfaces (47) slidably connected to the water spray button (46) being provided at both ends of the push plate (45).

6. The automotive motor performance dynamic testing device according to claim 1 is characterized in that: The first disc (19), the second disc (25), the first gear (27) and the second gear (28) are all made of a high-strength, impact-resistant alloy material.

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