Coolant supply system for electrically operated axles

Abstract

The invention relates to a coolant supply system for a power device of an electrically operated vehicle axle, the power device having an electric machine, the electric machine having a cylindrical stator housing (2), in which winding head spaces (27) are present on both axial sides of a rotor / stator assembly, coolant is collected at the bottom of the winding head spaces, two winding head spaces (27) are connected to each other in terms of flow technology via coolant collecting grooves (54, 55), the stator housing structural height (h1) and the coolant collecting groove structural height (h2) in the motor height direction (z) add up to a total structural height (h ges According to the present invention, in order to reduce the overall structural height (h ges ), the coolant collecting grooves (54, 55) are offset from the rotor axis vertical plane (V) by a lateral offset (Δx). Therefore, the stator housing structure height (h1) and the coolant collecting groove structure height (h2) can at least partially overlap with an overlap dimension (Δz) in the motor height direction (z).

Description

Technical Field

[0001] The invention relates to a coolant supply system for a power unit of an electrically operated axle of a two-track vehicle according to the preamble of claim 1 or according to the preamble of claim 10 . Background Art

[0002] In electrically operated two-track vehicles, the electrically driven axle can have an electric motor, for example. The electric motor can be arranged with its axis parallel to the flanged shaft leading to the vehicle wheels. In this case, the electric motor can drive the axle differential via a single-stage or double-stage spur gear transmission stage and further drive the flanged shaft of the axle leading to the vehicle wheels.

[0003] Such an electric machine can be realized as a wet-running electric machine, which has a cylindrical stator housing. A stator / rotor assembly is mounted in the cylindrical stator housing. A winding head space is present on both sides of the stator / rotor assembly in the axial direction, and coolant flowing out into the coolant collecting tank is collected at the bottom of the winding head space. The two winding spaces are connected to each other in terms of flow technology via the coolant collecting tank.

[0004] In the prior art, the coolant collecting tank is arranged vertically aligned and centered at the lowest point below the rotor axis. The coolant collecting tank extends substantially over the entire axial length of the stator housing. This stator housing geometry is problematic in terms of packaging optimization, because the stator housing structural height and the coolant collecting tank structural height add up to a relatively large total structural height. Reducing the total structural height by reducing the coolant collecting tank flow cross section is not feasible in terms of the functionality of the coolant collecting tank. In addition, from the perspective of manufacturing technology (i.e., casting technology), such a reduction in the coolant collecting tank flow cross section is not easy to achieve.

[0005] An oil pan with a collecting space divided into two parts is known from DE 10 2019 114 476 A1. An oil pan for a motor is known from DE 2 139 740 A. A transmission oil chamber is known from DE 10 2008 040 691 A1.

[0006] CN 112 271 876 A discloses a coolant supply system. DE 11 2011 103349 T5 discloses a coolant discharge system and method for an electric motor. EP 3 411 941 B1 discloses a cooling device for an electric motor. CN 109 997 296 A discloses a rotor, an electric motor and a method for manufacturing a rotor. CA 2 116900 A1 discloses a similar coolant supply system. Summary of the invention

[0007] The object of the present invention is to provide a coolant supply system for a drive unit of an electrically operated axle of a two-track vehicle which coolant supply system requires less installation space in the direction of the height of the electric machine than in the prior art.

[0008] This object is achieved by the features of the independent claim. Preferred developments of the invention are disclosed in the dependent claims.

[0009] The present invention proposes a coolant supply system for a power device of an electrically operated axle of a two-track vehicle. The power device has a wet-running motor. A rotor / stator assembly is installed in a cylindrical stator housing of the motor. Winding head spaces are respectively present on both sides of the rotor / stator assembly. The coolant flowing out into the coolant collecting trough is collected at the bottom of the winding head space. The two winding head spaces are connected to each other in terms of flow technology through the coolant collecting trough. According to the characterizing portion of claim 1, the overall structural height of the motor is reduced in the following manner: the coolant collecting trough is positioned to be offset from the vertical plane of the rotor axis by a lateral offset. In this way, the structural height of the stator housing and the structural height of the coolant collecting trough can be at least partially overlapped with an overlapping dimension in the motor height direction. Therefore, compared with the prior art, the overall structural height of the motor is reduced by the overlapping dimension.

[0010] The coolant collecting trough can extend continuously along the axial direction of the stator housing over the entire axial length of the stator housing. In addition, taking into account different driving operating conditions, such as accelerating, turning, uphill driving or downhill driving, the coolant collecting trough is designed in the following manner: the coolant collecting trough is divided into two overflow channels / swing channels (Schwappkanal) according to the present invention. The overflow channels are arranged on both sides of the vertical plane of the rotor axis with a transverse offset.

[0011] According to the invention, the motor is installed in a transverse installation with the axis parallel to the axle. In this case, the first suction point can be located in particular on the left side of the vehicle, and the second suction point can be located on the right side of the vehicle. Therefore, when the vehicle turns left, the coolant in the coolant collecting tank (or in the overflow channel) moves to the right suction point due to the centrifugal force. In contrast, when turning right, the coolant in the coolant collecting tank (or in the overflow channel) moves to the left suction point due to the centrifugal force. Therefore, the coolant can be reliably guided back to the coolant tank from the first suction point or from the second suction point when turning.

[0012] Furthermore, when the vehicle is traveling uphill or downhill, an operationally reliable coolant circulation is ensured by the two overflow channels. When traveling uphill, the overflow channel at the rear in the direction of travel ensures a fluidic connection between the winding head spaces. When traveling downhill, the overflow channel at the front in the direction of travel ensures a fluidic connection between the winding head spaces.

[0013] In the axle, the electric machine can drive the axle differential via a single-stage or double-stage spur gear transmission stage and from there further drive the flanged shaft of the axle leading to the vehicle wheels. In this case, it is preferred that the coolant supply system additionally has a transmission hydraulic circuit. The transmission hydraulic circuit can include a coolant tank, a transmission interior and a transmission sump formed at the bottom of the transmission. In the transmission sump, the coolant flowing out of the transmission components is collected at the transmission suction point and from there is returned to the coolant tank by means of a transmission return pump. The transmission can be flange-connected directly to an axial side of the stator housing of the electric machine, so that the stator housing extends axially together with the transmission housing.

[0014] In a preferred embodiment variant, the end wall of the stator housing close to the transmission can have a coolant passage. This coolant passage connects the winding head space close to the transmission with the transmission sump. The coolant passage can be positioned, for example, vertically aligned with the rotor axis. In this way, the suction point on the transmission side can suck out not only the coolant collected in the transmission sump, but also the coolant transferred from the stator housing in a dual-function manner.

[0015] For a flawless flow connection between two axially spaced winding head spaces, it is preferred that the overflow channel is connected to the corresponding winding head space at the coolant passage. It is also preferred that at least one of the two overflow channels is connected to the transmission sump via a channel opening.

[0016] In a particularly preferred embodiment variant, two suction locations can be positioned in a diagonal arrangement as described below. In this case, the suction location on the transmission side can be positioned on the same side with the overflow channel configured with a channel opening with reference to the rotor axis vertical plane. In contrast, the suction location away from the transmission and the overflow channel not connected to the transmission sump can be arranged on the opposite side with reference to the rotor axis vertical plane. Preferably, a return pump can be assigned to each suction location in the two suction locations. In an embodiment variant that is advantageous to the structural space, the return pump can be arranged on the same axial side of the stator housing, more precisely, in particular, arranged on the same axial side of the stator housing with the transmission. In this case, the suction location arranged on the axial side of the stator housing away from the pump or away from the transmission can be connected to the motor return pump through a return line. The stator housing can be implemented as a casting, and the overflow channel and the return line and the transverse channel material described later are identical and formed in one piece at the stator housing. The return line and the two overflow channels can extend parallel to the rotor axis.

[0017] A transverse channel can be formed on one of the axial sides of the stator housing, in particular on the axial side of the stator housing remote from the transmission. The two overflow channels and preferably the return line lead into the transverse channel. The transverse channel can establish a flow connection between the two overflow channels and the winding head space.

[0018] For this purpose, the transverse channel is connected to the winding head space at the coolant passage. The transverse channel can provide a dual function, not only as a flow connection, but also as a receiving space in which a sieve element that filters the coolant flowing through can be installed.

[0019] Furthermore, according to the invention, a coolant supply system for a power device of an electrically operated axle is provided, the power device having an electric machine, the electric machine having a cylindrical stator housing, in which winding head spaces are present on both axial sides of the rotor / stator assembly, in which coolant is collected at the bottom of the winding head spaces, wherein the two winding head spaces are connected to each other in terms of flow technology via a coolant collecting trough, and wherein the stator housing structural height and the coolant collecting trough structural height add up to a total structural height in the motor height direction, and wherein, in order to reduce the total structural height, the coolant collecting trough is offset from a rotor axis vertical plane by a transverse offset, so that the stator housing structural height and the coolant collecting trough structural height at least partially overlap in the motor height direction with an overlapping dimension, wherein a motor hydraulic circuit is provided, in which a coolant collecting trough is incorporated, and the coolant can be returned from the coolant collecting trough to a coolant tank at a suction point by means of at least one return pump. According to the invention, a transverse channel is formed on an axial side of the stator housing, into which the two transfer channels open, wherein the transverse channel connects the two transfer channels to one another. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The following is an explanation of the embodiments of the present invention with reference to the accompanying drawings.

[0021] Figure 1 An electric machine equipped with a coolant supply system is shown in a roughly schematic cross-sectional view;

[0022] Figures 2 to 4 Different sectional views of the electric machine are shown accordingly. DETAILED DESCRIPTION

[0023] exist Figure 1 , a power unit for an axle of a two-track vehicle is shown. The power unit has an electric motor which is arranged in a transverse mounting with its axis parallel to a flange shaft 3 leading to the vehicle wheels. A stator 4 and a rotor 5 interacting with the stator are arranged in a stator housing 2 of the electric motor. A rotor shaft 6 is rotatably supported in a bearing opening at axially opposite housing walls 8, 9 of the stator housing 2. The rotor shaft 6 of the electric motor is connected to a transmission input shaft 17 of a transmission 19 in a rotationally fixed manner, for example, by a key connection. Figure 1 In the embodiment, the transmission mechanism 19 is realized as a two-pole spur gear transmission stage, which transmits to the axle differential 20. Figure 1 In the figure, for the sake of clarity, the axle differential 20 is positioned outside the transmission housing 21. In practice, the axle differential 20 can be positioned in the transmission housing 21 together with the two-pole spur gear transmission.

[0024] exist Figure 1 In the embodiment, the stator 4 has a plurality of stator windings. Figure 1 Only two of the stator windings 21 are roughly shown in the figure. Each stator winding 21 has winding heads on both sides of the axial direction, and the winding heads extend into the winding head space 27. Each winding head space 27 is incorporated into the motor hydraulic circuit E described later, with the help of which the corresponding winding head space 27 can be loaded with coolant to cool the winding heads of the stator 4. In each winding head space 27, the coolant / air mixture moves in the form of a vortex around the rotor shaft 5 rotating at high speed.

[0025] Also like Figure 1As shown, the motor hydraulic circuit E has a coolant tank 35, which is connected to a suction pump 37 via a suction line. The pressure line leads from the suction pump 37 to the coolant supply lines 41, 43. The coolant is provided to the annular gap 45 surrounding the radial outside through the supply line 41. From the annular gap, the coolant is guided to another annular gap 49 in the right winding head space 27 through the radially outer stator channel 47. The two annular gaps 45, 47 are separated from the corresponding winding head space 27 by a splash ring 44. Each splash ring 44 has nozzles 46 distributed in the circumferential direction, through which the coolant (i.e., oil) can be splashed into the corresponding winding head space 27.

[0026] The coolant is guided by means of the supply line 43 through the rotor shaft 6 and through the flow connection 51 into the radially inner stator channel 53 until it is guided into the right winding head space 27. Furthermore, the coolant is thrown radially outwards in the direction of the winding head starting from the flow connection 51 and from the right confluence opening of the radially inner stator channel 53.

[0027] The two winding head spaces 27 are separated from each other in a substantially coolant-tight manner in the stator housing interior space by means of the stator / rotor assembly. In order to provide a flow connection between the winding head spaces 27, two overflow channels 54, 55 ( Figure 2 ), the overflow extends in the axial direction over the entire axial length of the stator housing outside the stator housing. In order to reduce the overall structural height h ges ,exist Figure 2 In the embodiment, each of the two overflow channels 54, 55 is arranged to be offset by a transverse offset Δx relative to the rotor axis vertical plane V. In this way, the stator housing structural height h 1 In the motor height direction z, part of the overflow channel structure height h 2 The total structure height h ges The overlap size Δz is reduced.

[0028] exist Figure 1 In the figure, the transmission mechanism 19 is flange-connected to the axial side of the stator housing on the left. The internal space of the transmission mechanism 19 and the transmission mechanism sump 56 constructed at the bottom of the transmission mechanism are incorporated into the transmission mechanism hydraulic circuit G. In the transmission mechanism hydraulic circuit G, the coolant flowing out from the transmission mechanism components is collected at the suction point A1 on the transmission mechanism side. The suction point A1 on the transmission mechanism side is connected to the transmission mechanism return pump 58 through a return line 67 to return the coolant to the coolant storage tank 35. In addition, a coolant passage 60 is constructed in the housing end wall 8 of the stator housing 2 close to the transmission mechanism. The coolant passage connects the winding head space 27 close to the transmission mechanism with the transmission mechanism sump 56. In Figure 1or Figure 2 In the embodiment, the coolant passage 60 is positioned so as to be vertically aligned with the rotor axis R. In addition, the overflow channel 55 located at the rear in the travel direction FR is connected to the rotor axis R by means of a channel opening 61 ( Figure 2 ) is directly connected to the transmission sump 56, while the overflow channel 54 located in front in the travel direction FR is not directly connected to the transmission sump 56. Figure 2 In the embodiment, the two overflow channels 54, 55 are also connected to the winding head space 27 close to the transmission mechanism at the coolant passages 48, 50.

[0029] As already mentioned, in Figure 1 In the case of a transverse installation, the motor is installed with its axis parallel to the axle. Figure 1 In the embodiment, the suction part A1 on the transmission side is located on the left side of the vehicle, and the suction part A2 away from the transmission is located on the right side of the vehicle. When the vehicle turns left, the coolant moves toward the right suction part A2 through the overflow channels 54 and 55 due to the centrifugal force. On the contrary, when the vehicle turns right, the coolant moves toward the left suction part A1 through the overflow channels 54 and 55 due to the centrifugal force. Therefore, when turning, the coolant can be reliably introduced into the coolant tank 35 through the left suction part A1 or through the right suction part A2.

[0030] exist Figure 4 In the embodiment, a transverse channel 65 is constructed at the bottom of the stator housing on the axial side of the stator housing away from the transmission mechanism, into which two overflow channels 54, 55 and a return line 66 described later are led. The transverse channel 65 establishes a flow connection between the two overflow channels 54, 55 and the winding head space 27 away from the transmission mechanism. For this purpose, the transverse channel 65 is connected to the winding head space 27 away from the transmission mechanism at the coolant passage 69. A sieve element 64 can also be installed in the transverse channel 65, which filters the coolant flowing through.

[0031] exist Figure 1 In the embodiment, the suction pump 37, the transmission return pump 58 and the motor return pump 71 are components of a multi-pump (combination pump). In this multi-pump, each individual pump is driven via a common drive shaft. The common drive shaft is in turn connected to the motor used as a power device. Figure 1 In the embodiment, all pumps 37, 58, 71 are advantageously positioned on the left axial side of the stator housing in terms of structural space. The suction point A2 arranged on the axial side of the stator housing away from the pump is connected to the motor return pump 71 through a return line 66. In the drawings, the return line 66 axis is parallel to the two overflow channels 54, 55. The stator housing 2 can preferably be realized as a casting, and the two overflow channels 54, 55 and the return line 66 are formed in the same material and in one piece at the stator housing.

[0032] In order to ensure reliable coolant circulation in different driving operating conditions (i.e., cornering and / or uphill and downhill driving), it is preferred that the two suction points A1, A2 are arranged diagonally with reference to the rotor axis vertical plane V. For this purpose, the suction point A1 on the transmission side and the channel opening 61 of the overflow channel 55 located at the rear in the driving direction FR are arranged at the rear and on the left side of the vehicle with reference to the rotor axis vertical plane V. Figure 2 The suction point A2 away from the transmission (i.e., the confluence opening of the return line 66 away from the transmission) is located on the right side of the vehicle and in the driving direction FR (i.e., with reference to the vertical plane V of the rotor axis) is located in front ( Figure 1 and Figure 4 ).

[0033] List of reference numerals:

[0034] 2 Stator housing

[0035] 3 Flange shaft

[0036] 4 Stator

[0037] 5 Rotor

[0038] 6 Rotor shaft

[0039] 8,9 Shell wall

[0040] 17 Transmission input shaft

[0041] 19 Transmission mechanism

[0042] 21 Stator winding

[0043] 27 Winding head space

[0044] 35 Coolant tank

[0045] 37 Suction pump

[0046] 41, 43 Coolant supply lines

[0047] 44 Coolant Splash Ring

[0048] 45 Annular gap

[0049] 46 Nozzle

[0050] 47 Radially outer stator channel

[0051] 48 Coolant passage

[0052] 49 Annular gap

[0053] 50 Coolant passage

[0054] 51 Flow connection

[0055] 53 Radially inner stator channel

[0056] 54, 55 Overflow channel

[0057] 56 Transmission mechanism sump

[0058] 58 Transmission return pump

[0059] 59 Motor return pump

[0060] 60 Coolant passage

[0061] 61 Channel opening

[0062] 63 Transmission mechanism internal space

[0063] 64 Screen element

[0064] 65 Horizontal channel

[0065] 66 Return pipeline

[0066] 67 Return pipeline

[0067] 69 Coolant passage

[0068] 71 Motor return pump

[0069] V Vertical plane of rotor axis

[0070] 54, 55 Overflow channel

[0071] R Rotor axis

[0072] h 1 Stator housing structure height

[0073] h 2 Overflow channel structure height

[0074] h ges Overall structure height

[0075] Δz overlap size

[0076] Δx lateral misalignment

[0077] E Motor hydraulic circuit

[0078] G Transmission hydraulic circuit

[0079] A1 Suction area on the transmission side

[0080] A2 A suction point away from the transmission mechanism

[0081] R Rotor axis

[0082] V Vertical plane of rotor axis

[0083] Z tooth meshing position

Claims

1. A coolant supply system for a power device of an electrically operated vehicle axle, the power device having an electric machine, the electric machine having a cylindrical stator housing (2), in which there are winding head spaces (27) on both axial sides of the rotor / stator assembly, and coolant is collected at the bottom of the winding head space, wherein: The two winding head spaces (27) are connected to each other in terms of flow technology via a coolant collecting trough, wherein the stator housing structural height (h1) and the coolant collecting trough structural height (h2) are added in the height direction (z) of the motor to form a total structural height (h ges ), In order to reduce the total structure height (h ges ), the coolant collecting tank is offset from the rotor axis vertical plane (V) by a lateral offset (Δx), so that the stator housing structure height (h1) and the coolant collecting tank structure height (h2) at least partially overlap in the machine height direction (z) by an overlap dimension (Δz), The motor is installed in a transverse manner parallel to the axle axis. It is characterized in that The coolant collecting tank is divided into two overflow channels, and the two overflow channels are arranged on both sides of the vertical plane (V) of the rotor axis with a lateral offset (Δx). When the vehicle is traveling uphill, a first overflow channel (55) located at the rear in the driving direction (FR) ensures the overflow of coolant between the winding head spaces (27) due to the lateral force, or when the vehicle is traveling downhill, a second overflow channel (54) located at the front in the driving direction (FR) ensures the overflow of coolant between the winding head spaces (27) due to the lateral force.

2. The coolant supply system according to claim 1, characterized in that: The coolant collecting groove continuously extends along the axial direction of the stator housing over the entire axial length of the stator housing.

3. The coolant supply system according to claim 1 or 2, characterized in that: A motor hydraulic circuit (E) is provided, in which a coolant sump is incorporated, from which coolant can be returned to a coolant tank (35) at a suction point by means of at least one return pump (58, 71).

4. The coolant supply system according to claim 3, characterized in that: The suction part comprises a first suction part (A1) and a second suction part (A2), wherein the first suction part (A1) close to the transmission mechanism is located on one side of the vehicle, and the second suction part (A2) far from the transmission mechanism is located on the other side of the vehicle.

5. The coolant supply system according to claim 3, characterized in that: The suction part comprises a left suction part and a right suction part. When the vehicle turns left, the coolant in the coolant collecting tank moves to the right suction part due to the action of centrifugal force, or when the vehicle turns right, the coolant in the coolant collecting tank moves to the left suction part due to the action of centrifugal force, so that the coolant can be reliably guided back to the coolant storage tank (35) at the left suction part or the right suction part when turning.

6. The coolant supply system according to claim 3, characterized in that: In the power device, the motor drives a flange shaft (3) leading to a vehicle wheel through a transmission mechanism (19), and a transmission mechanism hydraulic circuit (G) is provided, in which a transmission mechanism space (63) and a transmission mechanism sump (56) constructed at the bottom of the transmission mechanism are incorporated, and the coolant flowing out of the transmission mechanism components is collected in the transmission mechanism sump at the suction position on the transmission mechanism side. The coolant can be returned from the transmission mechanism sump to the coolant storage tank (35) through a transmission mechanism return pump (58). The transmission mechanism (19) is arranged on the axial side of the stator housing.

7. The coolant supply system according to claim 6, characterized in that: The end wall (8) of the stator housing (2) close to the transmission mechanism has a first coolant passage (60), which connects the winding head space (27) close to the transmission mechanism with the transmission mechanism collecting tank (56), so that the suction part on the transmission mechanism side not only sucks out the coolant collected in the transmission mechanism collecting tank (56) but also sucks out the coolant transferred from the stator housing (2) in a dual-function manner.

8. The coolant supply system according to claim 7, characterized in that: The first coolant passage (60) is positioned to be vertically aligned with the rotor axis (R), and / or the two overflow channels are connected to the corresponding winding head spaces (27) through additional coolant passages.

9. The coolant supply system according to claim 7, characterized in that: At least one of the two overflow channels is connected to the transmission mechanism liquid collecting tank (56) through a channel opening (61).

10. The coolant supply system according to claim 3, characterized in that: The return pumps (58, 71) are arranged on the same axial side of the stator housing, the suction portion arranged on the axial side away from the pump is connected to the motor return pump (71) through a return pipeline (66), and / or the first overflow channel (55) having a channel opening (61) and the suction portion on the transmission side are positioned on the same side with reference to the vertical plane (V) of the rotor axis, and / or the suction portion away from the transmission or away from the pump and the second overflow channel (54) not connected to the transmission sump (56) are arranged on opposite sides with reference to the vertical plane (V) of the rotor axis, so that the suction portion on the transmission side and the suction portion away from the transmission are arranged and positioned in a diagonal manner with reference to the vertical plane (V) of the rotor axis.

11. The coolant supply system according to claim 1 or 2, characterized in that: A transverse channel (65) is formed on the axial side of the stator housing, into which both overflow channels and a return line (66) open, and the transverse channel (65) connects the two overflow channels to one another.

12. The coolant supply system according to claim 11, characterized in that: The transverse channel is located on the axial side of the stator housing remote from the transmission mechanism.

13. The coolant supply system according to claim 11, characterized in that: The transverse channel (65) is connected to the winding head space (27) at a coolant passage.

14. The coolant supply system according to claim 11, characterized in that A sieve element (64) for filtering the coolant flowing through can be installed in the transverse channel (65).

15. A coolant supply system for a power device of an electrically operated vehicle axle, the power device having an electric machine, the electric machine having a cylindrical stator housing (2), in which there are winding head spaces (27) on both axial sides of the rotor / stator assembly, and coolant is collected at the bottom of the winding head space, in, The two winding head spaces (27) are fluidically connected to one another via a coolant collecting trough, wherein the stator housing structural height (h1) and the coolant collecting trough structural height (h2) are added together in the height direction (z) of the electric machine to form a total structural height (hges). In order to reduce the overall structural height (hges), the coolant collecting tank is offset from the rotor axis vertical plane (V) by a transverse offset (Δx), so that the stator housing structural height (h1) and the coolant collecting tank structural height (h2) at least partially overlap in the machine height direction (z) by an overlap dimension (Δz), A motor hydraulic circuit (E) is provided, in which a coolant sump is incorporated, from which coolant can be fed back into a coolant tank (35) at a suction point by means of at least one return pump (58, 71). It is characterized in that The coolant collecting tank is divided into two overflow channels, and the two overflow channels are arranged on both sides of the vertical plane (V) of the rotor axis with a lateral offset (Δx). A transverse channel (65) is formed on the axial side of the stator housing, into which the two overflow channels open, and the transverse channel (65) connects the two overflow channels to one another.

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