A low-wear mechanical commutator and motor

Abstract

The present application discloses a low-wear mechanical commutator and a motor, comprising: a rotating shaft, a swinging assembly, a commutation wobble plate and a commutation assembly, wherein the center point of the commutation assembly is on the center line of the rotating shaft, the center line of the commutation assembly forms an angle α with the center line of the rotating shaft, the commutation assembly is a fixed part, a conductive ring is provided on the commutation wobble plate, the conductive ring is formed by a plurality of contacts in close contact, the conductive ring is connected to a power supply, a plurality of contacts evenly spaced are provided on the commutation assembly, the rotating shaft is connected to the commutation wobble plate through the swinging assembly, and when the rotating shaft rotates, the commutation wobble plate periodically swings at a certain inclination angle in any circumferential direction thereof to switch the contacts to contact the contacts on the commutation assembly, thereby realizing non-sliding swing commutation. The present application improves the existing commutator sliding commutation into a swinging non-sliding commutation, thereby solving the problems of easy wear and electric sparks caused by sliding contact in current brushed motors.

Description

Technical Field

[0001] The present application relates to the field of commutators and motors, and specifically to a low-wear mechanical commutator and motor. Background Art

[0002] The sliding commutation motor, also known as the brushed DC motor or brushed DC motor, is a common type of motor that uses mechanical contacts to achieve the commutation of the current. Although this motor performs well in many applications, it also has some significant disadvantages, as follows:

[0003] 1. Limited life due to wear: The mechanical contact between the brushes and the commutator causes wear. Over time, the brushes gradually become shorter and the commutator is damaged. This not only increases maintenance costs, but may also lead to motor failure. Due to wear, the life of the sliding commutation motor is usually shorter than that of the brushless motor.

[0004] 2. Not suitable for high reliability applications: For applications that require long-term continuous operation or high reliability, sliding commutation motors cannot meet the requirements.

[0005] 3. Cost: Although the initial cost of a sliding-commutation motor is generally low, the total cost of long-term operation may be high due to the cost of maintenance and replacement parts.

[0006] In summary, sliding commutation motors are still widely used in many traditional applications, but the defects caused by friction in sliding commutation have not been properly resolved. Summary of the invention

[0007] The present application provides a low-wear mechanical commutator and a motor, which have the advantages of low wear and low cost and can solve the problems in the above-mentioned background technology.

[0008] The technical solution adopted by the present application to solve its technical problems is: a low-wear mechanical commutator, including a rotating shaft, a swinging assembly, a commutation wobble plate and a commutation assembly, the center point of the oscillating assembly is on the center line of the rotating shaft, the center line of the oscillating assembly forms an angle α with the center line of the rotating shaft, the commutation assembly is a fixed part, a conductive ring is provided on the commutation wobble plate, the conductive ring is formed by a plurality of contacts in close contact, the conductive ring is connected to a power supply, a plurality of evenly spaced contacts are provided on the commutation assembly, the rotating shaft is connected to the commutation wobble plate through the swinging assembly, and under the action of the swinging assembly, when the rotating shaft rotates, the commutation wobble plate periodically swings at a certain inclination angle along any circumferential direction thereof to switch the contacts to contact the contacts on the commutation assembly, thereby realizing non-sliding swing commutation.

[0009] Preferably, the swing component is a bearing.

[0010] Preferably, the phase-changing assembly includes a first phase-changing disk and a second phase-changing disk, the first phase-changing disk and the second phase-changing disk are arranged in parallel, and a plurality of evenly spaced contacts are provided on opposite sides of the two phase-changing disks, and the plurality of evenly spaced contacts are arranged in a quasi-annular manner. The phase-changing wobble disk is located between the first phase-changing disk and the second phase-changing disk, and the conductive ring is arranged on the outer circumference of both sides of the phase-changing wobble disk. When the rotating shaft rotates, the phase-changing wobble disk, under the action of the swinging assembly, periodically swings toward the first phase-changing disk or the second phase-changing disk at a certain inclination angle in any direction of its circumference, so that the switching contacts contact the contacts on the first phase-changing disk and the second phase-changing disk, thereby realizing non-sliding swing phase-changing.

[0011] Preferably, the phase-changing assembly includes a phase-changing ring, an inner ring of the phase-changing ring is provided with a phase-changing ring groove, contacts are arranged on both side surfaces of the phase-changing ring groove, a phase-changing wobble plate is located parallel to the inner ring of the phase-changing ring and the outer ring is placed inside the phase-changing ring groove, and a conductive ring is arranged on both sides of the outer ring of the phase-changing wobble plate. When the rotating shaft rotates, the phase-changing wobble plate, under the action of the swinging assembly, periodically swings toward both sides of the phase-changing ring groove at a certain inclination angle along any circumferential direction thereof, so that the switching contacts contact the contacts on the phase-changing ring, thereby realizing non-sliding swing phase-changing.

[0012] Preferably, the phase-changing component includes a phase-changing ring, the inner ring of the phase-changing ring is a protrusion structure, the contacts are arranged on both sides of the protrusion of the phase-changing ring, the outer ring of the phase-changing wobble plate is matched with the protrusion structure of the phase-changing ring and has a groove, the phase-changing wobble plate is located parallel to the inside of the phase-changing ring, and the conductive rings are arranged on both sides of the groove of the phase-changing wobble plate. When the rotating shaft rotates, the phase-changing wobble plate, under the action of the swinging component, periodically swings along any direction of its circumference at a certain inclination angle toward both sides of the protrusion of the phase-changing ring to contact the contacts on the phase-changing ring, thereby realizing non-sliding swing phase-changing.

[0013] Preferably, the phase-changing wobble plate is connected to an anti-rotation assembly, and the anti-rotation assembly limits the phase-changing wobble plate to prevent the phase-changing wobble plate from rotating during the swinging process.

[0014] Preferably, the anti-rotation assembly includes a latch, which connects the commutation wobble plate to the inside of the commutation device to prevent the commutation wobble plate from rotating during the swaying process.

[0015] Preferably, the anti-rotation assembly includes a latch and a slide slot, the latch is connected to the phase-changing wobble plate via the slide slot, the slide slot is a fixed part, and the latch and the slide slot cooperate to prevent the phase-changing wobble plate from rotating during the swinging process.

[0016] Preferably, the contacts on the conductive ring, the first commutation disk and the second commutation disk are tooth-type three-dimensional contacts. When the contacts on the conductive ring are in contact with the contacts of the first commutation disk and the second commutation disk respectively, the rotation of the commutation wobble disk during the swinging process is limited by the meshing of equal teeth between the teeth while power is turned on.

[0017] Preferably, the phase-changing ring groove is an annular groove, the contacts are arranged on both side surfaces of the annular groove, and the phase-changing wobble plate is an annular structure.

[0018] Preferably, the commutation ring groove is a conical groove, the contacts are arranged on both side surfaces of the conical groove, and the outer ring of the commutation wobble plate is a conical protrusion.

[0019] Preferably, the inner ring of the commutation ring is a conical protrusion, the contacts are arranged on both sides of the conical protrusion, and the outer ring of the commutation wobble plate is matched with the conical protrusion of the commutation ring and is provided with a conical groove.

[0020] Preferably, the rotating shaft is a common motor rotor shaft or is directly connected to the motor rotor shaft as a power input end.

[0021] Preferably, the angle α ranges from 0° to 10°.

[0022] An electric motor comprises any one of the low-wear mechanical commutators described above.

[0023] A vehicle adopts any one of the low-wear mechanical commutator or motor described above.

[0024] The substantial effects of this application are:

[0025] 1. When the shaft of the low-wear mechanical commutator rotates, under the action of the swing assembly, the commutation wobble plate periodically swings at a certain inclination angle along any direction of its circumference to switch the contact points on the commutation assembly, realizing non-sliding swing commutation. By switching the commutation electrodes in a non-sliding manner, the high wear problem caused by the sliding manner of the traditional commutator is solved;

[0026] 2. This low-wear mechanical commutator connects the commutation wobble plate to the anti-rotation assembly, which limits the commutation wobble plate to prevent the commutation wobble plate from rotating during the swaying process, thereby further reducing friction;

[0027] 3. This low-wear mechanical commutator adopts gear-type three-dimensional contacts. When the contacts on the conductive ring contact the first commutation disk and the second commutation disk respectively, the commutation wobble disk is restricted from rotating during the swinging process by the meshing of equal teeth between the teeth while power is turned on. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a schematic cross-sectional structural diagram of a phase converter according to a first embodiment of the present application at one angle;

[0029] Figure 2 is a schematic diagram of a three-dimensional cross-sectional structure of a phase converter according to a first embodiment of the present application at one angle;

[0030] Figure 3 It is a schematic diagram of the three-dimensional structure of the phase converter of the first embodiment of the present application from one angle;

[0031] Figure 4 It is a schematic diagram of the three-dimensional structure of the phase-changing wobble plate of the first embodiment of the present application;

[0032] Figure 5 This is a schematic diagram of the structure of the first commutation disk of the first embodiment of the present application;

[0033] Figure 6 This is a schematic diagram of the structure of the second commutation disk of the first embodiment of the present application;

[0034] Figure 7 is a schematic structural diagram of the phase converter of Embodiment 2 of the present application;

[0035] Figure 8 is a schematic structural diagram of a phase converter according to a third embodiment of the present application;

[0036] Fig. 9 It is a structural schematic diagram of the inverter of the fourth embodiment of the present application.

[0037] In the figure: 1, rotating shaft; 2, swing assembly; 3, phase-changing wobble plate; 31, conductive ring; 4, first phase-changing plate; 5, second phase-changing plate; 6, phase-changing ring; 61, phase-changing ring groove. DETAILED DESCRIPTION

[0038] The technical solution of the present application is further described below through specific embodiments. Embodiment 1

[0039] like Figure 1-6 As shown, a low-wear mechanical commutator comprises a rotating shaft 1, a swinging assembly 2, a commutation wobble plate 3 and a commutation assembly. The rotating shaft 1 is a common motor rotor shaft or is directly connected to the motor rotor shaft as a power input end. The swinging assembly 2 uses a bearing, the center point of the bearing is on the center line of the rotating shaft 1, and the center line of the bearing forms an angle α with the center line of the rotating shaft 1. The angle α ranges from 0 to 10°. The commutation assembly is a fixed part, and the commutation assembly can be fixed on the commutator housing, such as Figure 1 , 2 As shown in , 3, 5 and 6, the phase-changing assembly includes a first phase-changing disk 4 and a second phase-changing disk 5, the first phase-changing disk 4 and the second phase-changing disk 5 are arranged in parallel, and a plurality of evenly spaced contacts are arranged on opposite sides of the two phase-changing disks, and the plurality of evenly spaced contacts are arranged in a quasi-annular manner, and the phase-changing wobble disk 3 is located between the first phase-changing disk 4 and the second phase-changing disk 5, as shown in FIG. Figure 4As shown, the commutation wobble disc 3 is provided with a conductive ring 31, which is formed by a number of contacts in close contact. The conductive ring 31 is connected to the power supply and is arranged at the outer circumference of the two sides of the commutation wobble disc 3. When the shaft 1 rotates, the commutation wobble disc 3 periodically swings and switches the contacts to the first commutation disc 4 or the second commutation disc 5 at a certain inclination angle along any direction of its circumference under the action of the swing assembly 2, and contacts are contacted with the contacts on the first commutation disc 4 and the second commutation disc 5 to realize non-sliding swing commutation. After the commutator is connected to the power supply, the power passes through the commutation wobble disc 3 and passes through the contacts to the conductive contacts of the first commutation disc 4 and the second commutation disc 5 respectively, and is loaded to the corresponding motor electrodes. The motor stator coil is energized and starts to rotate. When the motor rotates to the magnetic field commutation point, the commutation wobble disc 3 also swings to the commutation point and continues to rotate. The commutation wobble disc 3 starts to replace the contacts with the commutation disc. After replacing to the next contact, a commutation is completed to ensure that the motor continues to rotate, and this cycle repeats. Embodiment 2

[0040] like Figure 7 As shown, in this embodiment, the phase-changing component includes a phase-changing ring 6, and the inner ring of the phase-changing ring 6 is provided with a phase-changing ring groove 61, which is an annular groove, and the contacts are arranged on both side surfaces of the annular groove. The phase-changing wobble plate 3 is an annular structure, and the phase-changing wobble plate 3 is parallelly arranged in the inner ring of the phase-changing ring 6 and the outer ring is arranged inside the phase-changing ring groove 61, and the conductive ring 31 is arranged on both sides of the outer ring of the phase-changing wobble plate 3. When the rotating shaft 1 rotates, the phase-changing wobble plate 3, under the action of the swinging component 2, periodically swings along any direction of its circumference at a certain inclination angle to both sides of the phase-changing ring groove 61 to switch the contacts to contact the contacts on the phase-changing ring 6, thereby realizing non-sliding swing commutation, and solving the high wear problem caused by the sliding of the traditional phase converter. Embodiment 3

[0041] like Figure 8 As shown, in this embodiment, the phase-changing component includes a phase-changing ring 6, the inner ring of the phase-changing ring 6 is a conical protrusion, and the contacts are arranged on both sides of the conical protrusion. The outer ring of the phase-changing wobble plate 3 is matched with the conical protrusion of the phase-changing ring 6 and has a conical groove. The phase-changing wobble plate 3 is located parallel to the inside of the phase-changing ring 6, and the conductive ring 31 is arranged on both sides of the groove of the phase-changing wobble plate 3. When the rotating shaft 1 rotates, the phase-changing wobble plate 3, under the action of the swinging component 2, periodically swings along any direction of its circumference at a certain inclination angle toward both sides of the conical protrusion of the phase-changing ring 6 to contact the contacts on the phase-changing ring 6, thereby realizing non-sliding swing phase-changing, and solving the high wear problem caused by the sliding of the traditional phase converter. Embodiment 4

[0042] like Fig. 9As shown, in this embodiment, the phase-changing component includes a phase-changing ring 6, the phase-changing ring groove 61 is a conical groove, the contacts are arranged on the two side surfaces of the conical groove, the phase-changing wobble plate 3 is an annular structure, the outer ring of the phase-changing wobble plate 3 is a conical protrusion, the phase-changing wobble plate 3 is parallel to the inner ring of the phase-changing ring 6 and the outer ring is placed inside the phase-changing ring groove 61, and the conductive ring 31 is arranged on both sides of the outer ring of the phase-changing wobble plate 3. When the rotating shaft 1 rotates, the phase-changing wobble plate 3, under the action of the swinging component 2, periodically swings along any direction of its circumference at a certain inclination angle to both sides of the phase-changing ring groove 61 to contact the contacts on both side surfaces of the phase-changing ring 6 groove, thereby realizing non-sliding swing phase-changing, and solving the high wear problem caused by the sliding of the traditional phase converter. Embodiment 5

[0043] In order to prevent the phase-changing wobble plate 3 from rotating, the phase-changing wobble plate 3 can be connected to the phase-changing housing or the phase-changing assembly by using a rotation-stop assembly. The rotation-stop assembly can be a latch. For example, the phase-changing wobble plate 3 is connected to the phase-changing housing by using a latch. When the rotating shaft 1 rotates, the phase-changing wobble plate 3 is prevented from rotating during the swinging process. The rotation-stop assembly can be a latch and a slide. The slide is fixedly connected to the phase-changing housing. The latch connects the slide and the phase-changing wobble plate 3. When the rotating shaft 1 rotates, the latch and the slide cooperate to prevent the phase-changing wobble plate 3 from rotating during the swinging process. The slide can be a single slide, a double slide or a cross slide. The rotation-stop assembly is used to prevent the phase-changing wobble plate 3 from rotating during the swinging process, which solves the high wear problem caused by the sliding mode of the traditional phase-changing device. Embodiment 6

[0044] Based on the first embodiment, in order to prevent the phase-changing wobble plate 3 from rotating, the contacts of the phase-changing wobble plate 3, the first phase-changing plate 4 and the second phase-changing plate 5 are designed as tooth-type three-dimensional contacts. When the shaft 1 rotates, the contacts on the conductive ring 31 contact the contacts of the first phase-changing plate 4 and the second phase-changing plate 5 respectively, and when power is turned on, the rotation of the phase-changing wobble plate 3 during the swinging process is limited by the meshing of the teeth with equal numbers of teeth, thereby solving the problem of high wear caused by sliding of the traditional phase converter. Embodiment 7

[0045] A motor comprises a low-wear mechanical commutator as described in any one of embodiments 1 to 6. Embodiment 8

[0046] A vehicle adopts any low-wear mechanical commutator of embodiments 1 to 6 or the motor of embodiment 7.

[0047] The above-described embodiment is only a preferred solution of the present application and does not limit the present application in any form. There are other variations and modifications without exceeding the technical solution described in the claims.

Claims

1. A low-wear mechanical commutator, characterized in that: The invention comprises a rotating shaft (1), a swinging assembly (2), a phase-changing wobble plate (3) and a phase-changing assembly, wherein the center point of the swinging assembly (2) is located on the center line of the rotating shaft (1), the center line of the swinging assembly (2) and the center line of the rotating shaft (1) form an angle α, the phase-changing assembly is a fixed component, a conductive ring (31) is provided on the phase-changing wobble plate (3), the conductive ring (31) is formed by a plurality of contacts in close contact, the conductive ring (31) is connected to a power source, a plurality of contacts are provided on the phase-changing assembly at even intervals, the rotating shaft (1) is connected to the phase-changing wobble plate (3) through the swinging assembly (2), and the phase-changing wobble plate (3) is under the action of the swinging assembly (2), when the rotating shaft (1) rotates, the phase-changing wobble plate (3) periodically swings at a certain inclination angle along any direction of its circumference to switch the contacts to contact the contacts on the phase-changing assembly, thereby realizing non-sliding swing phase-changing. The phase-changing assembly comprises a first phase-changing disk (4) and a second phase-changing disk (5), the first phase-changing disk (4) and the second phase-changing disk (5) are arranged in parallel, and a plurality of evenly spaced contacts are arranged on opposite sides of the two phase-changing disks, and the plurality of evenly spaced contacts are arranged in a quasi-annular manner. The phase-changing wobble disk (3) is located between the first phase-changing disk (4) and the second phase-changing disk (5), and the conductive ring (31) is arranged at the outer circumference of the two side surfaces of the phase-changing wobble disk (3). When the rotating shaft (1) rotates, the phase-changing wobble disk (3) periodically swings at a certain inclination angle along any direction of its circumference toward the first phase-changing disk (4) or the second phase-changing disk (5) under the action of the swing assembly (2), and the switching contact contacts contact the contacts on the first phase-changing disk (4) and the second phase-changing disk (5), thereby realizing non-sliding swing phase-changing.

2. A low-wear mechanical commutator, characterized in that: The invention comprises a rotating shaft (1), a swinging assembly (2), a phase-changing wobble plate (3) and a phase-changing assembly, wherein the center point of the swinging assembly (2) is located on the center line of the rotating shaft (1), the center line of the swinging assembly (2) and the center line of the rotating shaft (1) form an angle α, the phase-changing assembly is a fixed component, a conductive ring (31) is provided on the phase-changing wobble plate (3), the conductive ring (31) is formed by a plurality of contacts in close contact, the conductive ring (31) is connected to a power source, a plurality of contacts are provided on the phase-changing assembly at even intervals, the rotating shaft (1) is connected to the phase-changing wobble plate (3) through the swinging assembly (2), and the phase-changing wobble plate (3) is under the action of the swinging assembly (2), when the rotating shaft (1) rotates, the phase-changing wobble plate (3) periodically swings at a certain inclination angle along any direction of its circumference to switch the contacts to contact the contacts on the phase-changing assembly, thereby realizing non-sliding swing phase-changing. The phase-changing assembly comprises a phase-changing ring (6), the inner ring of the phase-changing ring (6) is provided with a phase-changing ring groove (61), contacts are arranged on both side surfaces of the phase-changing ring groove (61), a phase-changing wobble plate (3) is arranged parallel to the inner ring of the phase-changing ring (6) and the outer ring is arranged inside the phase-changing ring groove (61), and a conductive ring (31) is arranged on both sides of the outer ring of the phase-changing wobble plate (3). When the rotating shaft (1) rotates, the phase-changing wobble plate (3) periodically swings along any direction of its circumference at a certain inclination angle to both sides of the phase-changing ring groove (61) under the action of the swing assembly (2), and the switching contacts contact the contacts on the phase-changing ring (6), thereby realizing non-sliding swing phase-changing.

3. A low-wear mechanical commutator, characterized in that: The invention comprises a rotating shaft (1), a swinging assembly (2), a phase-changing wobble plate (3) and a phase-changing assembly, wherein the center point of the swinging assembly (2) is located on the center line of the rotating shaft (1), the center line of the swinging assembly (2) and the center line of the rotating shaft (1) form an angle α, the phase-changing assembly is a fixed component, a conductive ring (31) is provided on the phase-changing wobble plate (3), the conductive ring (31) is formed by a plurality of contacts in close contact, the conductive ring (31) is connected to a power source, a plurality of contacts are provided on the phase-changing assembly at even intervals, the rotating shaft (1) is connected to the phase-changing wobble plate (3) through the swinging assembly (2), and the phase-changing wobble plate (3) is under the action of the swinging assembly (2), when the rotating shaft (1) rotates, the phase-changing wobble plate (3) periodically swings at a certain inclination angle along any direction of its circumference to switch the contacts to contact the contacts on the phase-changing assembly, thereby realizing non-sliding swing phase-changing. The phase-changing component comprises a phase-changing ring (6), the inner ring of the phase-changing ring (6) is a protruding structure, contacts are arranged on both sides of the protrusion of the phase-changing ring (6), the outer ring of the phase-changing wobble plate (3) is matched with the protruding structure of the phase-changing ring (6) and has a groove, the phase-changing wobble plate (3) is parallelly arranged inside the phase-changing ring (6), and the conductive ring (31) is arranged on both sides of the groove of the phase-changing wobble plate (3), when the rotating shaft (1) rotates, the phase-changing wobble plate (3) is periodically swung along any direction of its circumference at a certain inclination angle toward both sides of the protrusion of the phase-changing ring (6) under the action of the swing component (2), and the switching contacts contact the contacts on the phase-changing ring (6), thereby realizing non-sliding swing phase-changing.

4. The low-wear mechanical commutator according to any one of claims 1 to 3, characterized in that: The swing component (2) is a bearing.

5. The low-wear mechanical commutator according to any one of claims 1 to 3, characterized in that: The phase-changing wobble plate (3) is connected to the anti-rotation component, and the anti-rotation component limits the phase-changing wobble plate (3) to prevent the phase-changing wobble plate (3) from rotating during the swinging process.

6. The low-wear mechanical commutator according to claim 5, characterized in that: The anti-rotation assembly comprises a latch, which connects the phase-changing wobble plate (3) to the inside of the phase-changing device to prevent the phase-changing wobble plate (3) from rotating during the swinging process.

7. The low-wear mechanical commutator according to claim 5, characterized in that: The anti-rotation assembly comprises a latch and a slide slot, the latch being connected to the phase-changing wobble plate (3) via the slide slot, the slide slot being a fixed part, and the latch and the slide slot cooperate to prevent the phase-changing wobble plate (3) from rotating during the swinging process.

8. The low-wear mechanical commutator according to any one of claims 1 to 3, characterized in that: The contacts on the conductive ring (31), the first commutation disk (4) and the second commutation disk (5) are tooth-type three-dimensional contacts. When the contacts on the conductive ring (31) are in contact with the contacts of the first commutation disk (4) and the second commutation disk (5), respectively, the commutation disk (3) is restricted from rotating during the oscillation process by meshing the teeth with equal numbers of teeth when electricity is supplied.

9. The low-wear mechanical commutator according to claim 1, characterized in that: The phase-changing ring groove (61) is an annular groove, the contacts are arranged on both side surfaces of the annular groove, and the phase-changing wobble plate (3) is an annular structure.

10. The low-wear mechanical commutator according to claim 1, characterized in that: The phase-changing ring groove (61) is a conical groove, the contacts are arranged on both side surfaces of the conical groove, and the outer ring of the phase-changing wobble plate (3) is a conical protrusion.

11. The low-wear mechanical commutator according to claim 3, characterized in that: The inner ring of the phase-changing ring (6) is a conical protrusion, and the contacts are arranged on both sides of the conical protrusion. The outer ring of the phase-changing wobble plate (3) is provided with a conical groove to match the conical protrusion of the phase-changing ring (6).

12. The low-wear mechanical commutator according to any one of claims 1 to 4, characterized in that: The rotating shaft (1) is a common motor rotor shaft or is directly connected to the motor rotor shaft as a power input end.

13. The low-wear mechanical commutator according to any one of claims 1 to 4, characterized in that: The angle α ranges from 0 to 10°.

14. A motor, characterized in that: It comprises a low-wear mechanical commutator as described in any one of claims 1-13.

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