Heat dissipation structure suitable for thrust bearing of air compressor and air compressor

Abstract

The utility model provides a heat dissipation structure suitable for an air compressor thrust bearing and an air compressor, and belongs to the technical field of air compressors, the heat dissipation structure suitable for the air compressor thrust bearing comprises a water cooling structure and an air cooling structure, the water cooling structure comprises end cooling water channels distributed in the circumferential direction of an air compressor shell, the end cooling water channel is located at the front end of the shell, and the width direction of the end cooling water channel extends into the integrated radial bearing seat. The air cooling structure comprises an air cooling groove formed in the back side of the thrust bearing seat and a ventilation hole penetrating through the thrust bearing seat. And a notch of the air cooling groove is attached to the front end face of the integrated radial bearing seat to form an air cooling channel, and the air cooling channel and the end cooling water channel are horizontally arranged at intervals. According to the heat dissipation structure suitable for the thrust bearing of the air compressor, provided by the utility model, the end cooling water channel extends into the integrated radial bearing seat, so that the distance between an air cooling channel and a water cooling channel is shortened; and the air cooling effect is improved, and then the cooling effect on the thrust bearing is achieved.

Description

Technical Field

[0001] The utility model belongs to the technical field of air compressors, and more specifically relates to a heat dissipation structure suitable for a thrust bearing of an air compressor and an air compressor. Background Art

[0002] Existing air compressors mostly use a cooling method that combines water cooling and air cooling, wherein air cooling is mostly used to cool the thrust bearing and the center shaft, while water cooling is mostly used to cool the housing structure and the inner cavity of the housing.

[0003] At present, the heat dissipation of thrust bearings of air compressor products in the industry is mostly achieved through air cooling. Due to space and environmental limitations, the air cooling inlet channels are mostly irregular, the air flow direction is irregular, and the gas with excessively high temperature enters the air compressor, which will have a negative impact on the use of the thrust bearing, such as high energy consumption, high-temperature gas impacting the air compressor shaft system and causing instability. Since the air cooling flow channel structure is limited to the design of a fixed area, when the temperature of the thrust bearing is too high, the air cooling effect is not significant.

[0004] In view of the situation of internal air bleed of the air compressor, the internal air cooling method avoids the trouble of connecting the external cooling air duct and the problem that the external cooling air duct is easily damaged. However, the cooling temperature of the internal air is higher than the cooling temperature of the external air. Therefore, the cooling effect of the thrust bearing and other structures is poor when the internal air cooling method is used to cool the thrust bearing. In fact, the thrust bearing cannot be cooled in time, resulting in excessive temperature and burning failure. Utility Model Content

[0005] The purpose of the utility model is to provide a heat dissipation structure suitable for a thrust bearing of an air compressor and an air compressor, aiming to solve the problem of poor heat dissipation effect of the thrust bearing.

[0006] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is: to provide a heat dissipation structure suitable for the thrust bearing of an air compressor, including a water-cooling structure and an air-cooling structure, the water-cooling structure including an end cooling water channel distributed along the circumference of the air compressor casing, the end cooling water channel being located at the front end of the casing, and the width direction of the end cooling water channel extending into the integrated radial bearing seat; the air-cooling structure including an air-cooling groove opened on the back side of the thrust bearing seat and a ventilation hole passing through the thrust bearing seat; the notch of the air-cooling groove is fitted to the front end surface of the integrated radial bearing seat to form an air-cooling channel, and the air-cooling channel is horizontally spaced apart from the end cooling water channel.

[0007] As another embodiment of the present application, the air cooling groove is a spiral groove body distributed along the radial direction of the thrust bearing seat.

[0008] As another embodiment of the present application, the air-cooling groove further includes an annular cooling cavity located inside the air-cooling groove, the annular cooling cavity extends to the center hole of the thrust bearing seat, and the annular cooling cavity is connected to the air-cooling groove.

[0009] As another embodiment of the present application, there are multiple connecting grooves between the annular cooling cavity and the air cooling groove, and the multiple connecting grooves are arranged at intervals.

[0010] As another embodiment of the present application, a plurality of reinforcement parts are provided in the circumference of the center hole of the thrust bearing seat, the plurality of reinforcement parts are arranged at equal intervals, and a radial groove connected to the annular cooling cavity is provided between two adjacent reinforcement parts.

[0011] As another embodiment of the present application, the end cooling water channel axially includes a first cooling part located in the shell and a second cooling part located in the integrated radial bearing seat, and the first cooling part and the second cooling part are connected.

[0012] As another embodiment of the present application, the first cooling portion and the second cooling portion are connected via a conformal bending portion.

[0013] As another embodiment of the present application, the second cooling portion extends radially to the middle of the integrated radial bearing seat.

[0014] As another embodiment of the present application, the end cooling water channel includes a first end water channel and a second end water channel distributed at intervals, both ends of the first end water channel are connected to a middle cooling water channel opened in the air compressor casing, and both ends of the second end water channel are respectively connected to the outlet end and the liquid outlet of the middle cooling water channel, and the liquid outlet is opened on the side wall of the casing.

[0015] The beneficial effect of the heat dissipation structure for the thrust bearing of an air compressor provided by the utility model is that: compared with the prior art, the heat dissipation structure for the thrust bearing of an air compressor provided by the utility model increases the cooling coverage area of the radial bearing seat and the front end face of the shell by making a water channel in the radial bearing seat integrally arranged with the shell, thereby cooling and reducing the temperature of the integrated radial bearing seat and the thrust bearing seat attached to the integrated radial bearing seat. In addition, the end cooling water channel extends into the integrated radial bearing seat, which is close to the air cooling channel and is spaced apart from the air cooling channel, shortening the distance between the air cooling channel and the water cooling channel; the air in the air cooling channel is cooled by the end cooling water channel, thereby improving the air cooling effect, thereby improving the cooling effect of the air cooling channel on the thrust bearing.

[0016] An air compressor is also provided, comprising the heat dissipation structure applicable to the thrust bearing of the air compressor.

[0017] The beneficial effects of the air compressor provided by the present invention are as follows: compared with the prior art, the air compressor of the present invention increases the cooling coverage area of the radial bearing seat and the front end face of the housing by providing a water channel in the radial bearing seat integrally arranged with the housing, thereby cooling and reducing the temperature of the radial bearing seat and the thrust bearing seat, thereby improving the cooling effect; at the same time, the air cooling channel is attached to the integrated radial bearing seat, and the water channel will further cool the gas in the air cooling channel while cooling the integrated radial bearing seat, thereby achieving the effect of reducing the gas temperature in the air cooling channel and cooling the thrust bearing. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 A schematic structural diagram of an air compressor provided in an embodiment of the present utility model;

[0020] Figure 2 A longitudinal cross-sectional view of an air compressor housing provided by an embodiment of the present utility model;

[0021] Figure 3 A rear view of a thrust bearing seat provided in an embodiment of the present utility model;

[0022] Figure 4 A top view of the air compressor housing provided by an embodiment of the present utility model;

[0023] Figure 5 For the Figure 4 Cross-sectional view along line AA;

[0024] Figure 6 For the Figure 4 Cross-sectional view along the midline BB;

[0025] Figure 7 For the Figure 4 Cross-sectional view along the mid-CC line;

[0026] Figure 8 For the Figure 4 Cross-sectional view along the DD line.

[0027] In the figure: 1. Shell; 2. Liquid inlet pipe; 3. Liquid outlet pipe; 4. Tail cooling water channel; 5. Liquid inlet section; 6. Liquid outlet section; 7. First end water channel; 8. Thrust bearing seat; 9. Air cooling groove; 10. First filter section; 11. Second filter section; 12. Second end water channel; 13. Annular cooling chamber; 14. Reinforcement section; 15. Radial groove; 16. Ventilation hole. DETAILED DESCRIPTION

[0028] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0029] See also Figures 1 to 8 The heat dissipation structure for an air compressor thrust bearing and an air compressor provided by the present invention are now described. The heat dissipation structure for an air compressor thrust bearing includes a water-cooling structure and an air-cooling structure. The water-cooling structure includes end cooling water channels distributed along the circumference of the air compressor housing 1. The end cooling water channels are located at the front end of the housing 1, and the width direction of the end cooling water channels extends into the integrated radial bearing seat. The air-cooling structure includes an air-cooling groove 9 provided on the back side of the thrust bearing seat 8 and a ventilation hole 16 penetrating the thrust bearing seat 8. The notch of the air-cooling groove 9 is fitted on the front end surface of the integrated radial bearing seat to form an air-cooling channel. The air-cooling channel and the end cooling water channels are arranged horizontally and spaced apart.

[0030] The heat dissipation structure provided by the utility model is suitable for the thrust bearing of the air compressor. Compared with the existing technology, the integrated radial bearing seat and the thrust bearing seat 8 are cooled by a water cooling structure and an air cooling structure. The end cooling water channel extends to the shell 1 in the integrated bearing seat. By making a water channel in the radial bearing seat integrally arranged with the shell 1, the cooling coverage area of the water channel on the radial bearing seat and the front end face of the shell 1 is increased, thereby cooling and lowering the temperature of the integrated radial bearing seat and the thrust bearing seat 8 attached to the integrated radial bearing seat. In addition, the end cooling water channel extends into the integrated radial bearing seat, which is close to the air cooling channel and is spaced apart from the air cooling channel, shortening the distance between the air cooling channel and the water cooling channel; the air in the air cooling channel is cooled by the end cooling water channel, thereby improving the air cooling effect, thereby improving the cooling effect of the air cooling channel on the thrust bearing.

[0031] In some possible embodiments, see Figure 3 The air cooling groove 9 is a spiral groove body distributed along the radial direction of the thrust bearing seat 8.

[0032] Air cooling groove 9 is provided on the back end surface of thrust bearing seat 8. The trajectory of air cooling groove 9 is a gradually increasing groove shape along a spiral trajectory. The inner side of air cooling groove 9 covers approximately half of the end surface of thrust bearing seat 8. Ventilation holes 16 are provided at the bottom of air cooling groove 9 at any position and extend through thrust bearing seat 8.

[0033] The air cooling groove 9 also includes an annular cooling cavity 13 located inside the air cooling groove 9. The annular cooling cavity 13 extends to the center hole of the thrust bearing seat 8 and communicates with the air cooling groove 9. The air cooling groove 9 has at least two spiral turns. An annular cooling cavity 13 is also provided inside the spiral groove body and communicates with the notch of the air cooling groove 9.

[0034] Multiple connecting grooves are spaced between the annular cooling cavity 13 and the air cooling groove 9. Multiple connecting grooves are spaced apart on the sidewall of the innermost ring of the spiral groove body, near the annular cooling cavity 13. These connecting grooves can be either open slots or notches, and are integrally formed during processing. The multiple connecting grooves are evenly spaced, and the distance between the connecting groove closest to the air cooling groove 9 and the slot opening is equal to the spacing between the two connecting grooves.

[0035] In some possible embodiments, see Figure 3 A plurality of reinforcement portions 14 are provided around the center hole of the thrust bearing seat 8 . The plurality of reinforcement portions 14 are arranged at equal intervals. A radial groove 15 communicating with the annular cooling cavity 13 is provided between two adjacent reinforcement portions 14 .

[0036] Multiple equally spaced reinforcements 14 are used to increase the thickness of the central portion of the thrust bearing seat 8, thereby enhancing the strength of the thrust bearing seat 8. The annular cooling cavity 13 on the back side of the thrust bearing seat 8 has radial grooves 15 formed between adjacent reinforcements 14, extending from the annular cooling cavity 13 to the central hole of the thrust bearing seat 8 via the radial grooves 15 between the reinforcements 14.

[0037] In some possible embodiments, see Figure 2 The end cooling water channel includes a first cooling part located in the shell 1 and a second cooling part located in the integrated radial bearing seat along the axial direction, and the first cooling part is connected to the second cooling part.

[0038] The end cooling water channel is an arc-shaped water channel cavity in the water channel body located at the end of the shell 1, and the annular water channel cavity is located in the same plane.

[0039] The end cooling water channel is limited by the structural constraints of the housing 11's end. The front end of the housing 1 is equipped with a radial bearing seat, integral with the housing 1, known as an integrated radial bearing seat. This integrated radial bearing seat is radially close to the central axis of the housing 1. To improve cooling of the integrated radial bearing seat, a second cooling section is provided within the integrated radial bearing seat. The first cooling section is located at the front of the housing 1 and communicates with the second cooling section. Liquid in the first cooling section flows into the second cooling section, cooling the integrated radial bearing seat.

[0040] The first cooling part and the second cooling part can be connected through a plurality of through holes; the first cooling part and the second cooling part can be separated and through holes can be provided at the inlet and outlet ends of both to form parallel cold water channels.

[0041] Alternatively, the first cooling section and the second cooling section are connected via a conformal bend. The conformal bend is an inclined connecting notch located at the front connection of the housing 1 and the integrated radial bearing seat, connecting the first cooling section and the second cooling section to form an integrated cooling water channel.

[0042] The second cooling section extends radially to the middle of the integrated radial bearing seat; its coverage area is larger than one-third of the thrust bearing seat 8. By increasing the depth of the second cooling section, it is closer to the air cooling structure, shortening the distance between the water cooling channel and the air cooling channel, and achieving a more significant air cooling effect.

[0043] The second cooling part is connected to the edge of the transversely arranged first cooling part by means of a conformal bending part. The second cooling part is distributed along the thickness direction of the integrated radial bearing seat, that is, the thickness direction of the second cooling part is consistent with the axial direction of the shell 1, and the width direction of the second cooling part extends along the radial direction of the shell 1 toward the central axis until it extends to the middle of the integrated radial bearing seat, so as to increase the coverage area of water cooling and further improve the cooling effect of the integrated radial bearing seat.

[0044] During air compressor installation, the thrust bearing seat 8 is mounted in close proximity to the front of the integrated radial bearing seat. The air-cooling structure, which complements the water-cooling structure, must pass through the thrust bearing seat 8 and form an air-cooling channel behind it. Since the second cooling section extends into the interior of the integrated radial bearing seat, it is spaced apart from the air-cooling channel between the thrust bearing seat 8 and the integrated radial bearing seat. The cryogenic liquid within the second cooling section can transfer heat through the integrated radial bearing seat, cooling the integrated radial bearing seat, which in turn cools the gas within the air-cooling channel. This lowers the temperature of the gas within the air-cooling channel. The cooled gas has a more effective cooling effect on the thrust bearing.

[0045] The arrangement of the first and second cooling sections, as well as the conformal bend, optimizes the water-cooling channel structure. The addition of a sloped surface allows for smoother water flow within the channel, evenly distributing heat to the air-cooled system and ensuring a stable flow of air at a uniform temperature. By creating a sloped structure that facilitates water flow and increasing the channel depth, the distance between the air-cooling and water-cooling channels is significantly shortened, optimizing heat dissipation within the thrust bearing.

[0046] In some possible embodiments, see Figure 2 、 Figures 4 to 8 The water channel body also includes a tail cooling water channel 4 and a middle cooling water channel. The end cooling water channel is located at the front end of the middle cooling water channel and is connected to the middle cooling water channel; the middle cooling water channel includes a first middle arc-shaped water channel and a second middle arc-shaped water channel that are arranged opposite to each other. The inlet and outlet of the tail cooling water channel 4 are respectively connected to the rear end of the first middle arc-shaped water channel and the rear end of the second middle arc-shaped water channel; the liquid inlet is connected to the second middle arc-shaped water channel, and the liquid outlet is connected to the end cooling water channel.

[0047] The water channel body of the shell 1 comprises, arranged from rear to front, a tail cooling channel 4, a middle cooling channel, and end cooling channels. The tail cooling channel 4 is an annular structure with a clearance notch, primarily used to make way for the air cooling channel. To ensure its strength and to make way for the air cooling channel, the middle cooling channel is divided into two separate halves, each of which is disconnected. A first middle curved channel and a second middle curved channel are located within each half, connecting to the two ports of the tail cooling channel 4, forming a connected waterway.

[0048] According to the installation positions of the liquid inlet and outlet, the liquid inlet is positioned on the middle cooling water channel, and the liquid outlet is positioned on the end cooling water channel. Based on the space given to the air cooling channel and the distribution of the water cooling structure, the middle cooling water channel is divided into two groups, namely the first middle curved water channel and the second middle curved water channel. After the liquid enters the second middle curved water channel from the liquid inlet, it enters the tail cooling water channel 4, the first middle curved water channel, and the end cooling water channel in sequence, and finally discharges from the liquid outlet.

[0049] like Figures 4 to 8 As shown, the first middle arc-shaped water channel includes a first transition section and a second transition section arranged at intervals along the axial direction. The first transition section is located on the rear side of the second transition section. The inlet of the first transition section is connected to the outlet of the tail cooling water channel 4. The first transition section, the second transition section and the first end water channel 7 are connected in sequence.

[0050] After the liquid enters the tail cooling water channel 4 through the second middle curved water channel, it enters the first transition section of the first middle curved water channel from the tail cooling water channel 4. The first and second transition sections are both curved structures, with the outlet of the first transition section and the inlet of the second transition section located at the same end, connected by a notch in the housing 1. The inlet and outlet of the first transition section are located at the two ends of its length.

[0051] The second transition section is communicated with the end cooling water channel and is connected to the liquid outlet via the end cooling water channel.

[0052] like Figures 4 to 8 As shown, the second middle arc-shaped water channel includes a liquid inlet section 5 and a liquid outlet section 6 arranged at intervals along the axial direction. The liquid inlet section 5 is located on the rear side of the liquid outlet section 6. The inlet of the liquid inlet section 5 is connected to the liquid inlet, and the outlet of the liquid inlet section 5 is connected to the inlet of the tail cooling water channel 4; the end cooling water channel includes a first end water channel 7 and a second end water channel 12 distributed at intervals. The first end water channel 7 and the second end water channel 12 are arranged opposite to each other, and the inlet and outlet of the first end water channel 7 are respectively connected to the outlet of the first middle arc-shaped water channel and the inlet of the liquid outlet section 6; the inlet and outlet of the second end water channel 12 are respectively connected to the outlet and the liquid outlet of the liquid outlet section 6.

[0053] The second central curved water channel is connected to the liquid inlet and is positioned opposite the first central curved water channel. Correspondingly, the second central curved water channel is divided into two axially spaced arcuate segments: a liquid inlet segment 5 and a liquid outlet segment 6. Considering the spacing between the liquid inlet and outlet, the liquid inlet segment 5, which connects to the liquid inlet, is located at the rear, while the liquid outlet segment 6 is located in front of the liquid inlet segment 5, but is not connected to the liquid inlet segment 5.

[0054] The outlet of the liquid inlet section 5 is connected to the inlet of the tail cooling water channel 4. The liquid enters the tail cooling water channel 4 from the liquid inlet section 5, then passes through the first transition section, the second transition section, and the first end water channel 7 in sequence before entering the liquid outlet section 6. Finally, it enters the second end water channel 12 from the liquid outlet section 6 and is finally discharged from the liquid outlet connected to the second end water channel 12.

[0055] The first transition section and the liquid inlet section 5 are located in the same plane and are arranged opposite to each other. The second transition section and the liquid outlet section 6 are located in the same plane and are arranged opposite to each other.

[0056] like Figure 6 、 Figure 7 As shown, the central angle of the arc of the liquid outlet section 6 is greater than the central angle of the arc of the second end water channel 12, the inlet end of the liquid outlet section 6 extends to one side of the outlet of the first end water channel 7, the liquid outlet section 6 and the first end water channel 7 are connected by a notch extending in the axial direction, and the outlet end of the liquid outlet section 6 is flush with the inlet end of the second end water channel 12.

[0057] The coverage area of the liquid outlet section 6 is larger than that of the second end water channel 12. One end of the liquid outlet section 6 is flush with the end of the second end water channel 12, while the other end extends beyond the other end of the second end water channel 12 and covers one side of the first end water channel 7. The inlet end of the liquid outlet section 6 is connected to the first end water channel 7 through a notch, and the outlet end is connected to the second end water channel 12.

[0058] The liquid flow path is: liquid inlet → liquid inlet section 5 → tail cooling water channel 4 → first transition section → second transition section → first end water channel 7 → liquid outlet section 6 → second end water channel 12 → liquid outlet. The liquid inlet section 5 and first transition section are opposite each other, the liquid outlet section 6 and second transition section are opposite each other, and the first end water channel 7 and second end water channel 12 are opposite each other.

[0059] An air compressor is also provided, comprising the heat dissipation structure applicable to the thrust bearing of the air compressor.

[0060] Compared with the prior art, the air compressor provided by the present invention increases the cooling coverage area of the radial bearing seat and the front end face of the housing 1 by providing a water channel in the radial bearing seat integrally provided with the housing 1, thereby cooling and reducing the temperature of the radial bearing seat and the thrust bearing seat 8, thereby improving the cooling effect; at the same time, the air cooling channel is attached to the integrated radial bearing seat, and the water channel will further cool the gas in the air cooling channel while cooling the integrated radial bearing seat, thereby achieving the effect of reducing the gas temperature in the air cooling channel and cooling the thrust bearing.

[0061] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. Suitable for heat dissipation structure of thrust bearing of air compressor, characterized by: The invention comprises a water-cooling structure and an air-cooling structure, wherein the water-cooling structure comprises an end cooling water channel distributed along the circumference of the air compressor housing (1), the end cooling water channel is located at the front end of the housing (1), and the width direction of the end cooling water channel extends into the integrated radial bearing seat; the air-cooling structure comprises an air-cooling groove (9) opened on the back side of the thrust bearing seat (8) and a ventilation hole (16) passing through the thrust bearing seat (8); the notch of the air-cooling groove (9) is fitted on the front end surface of the integrated radial bearing seat to form an air-cooling channel, and the air-cooling channel is arranged horizontally with respect to the end cooling water channel.

2. The heat dissipation structure for an air compressor thrust bearing according to claim 1, characterized in that: The air cooling groove (9) is a spiral groove body distributed along the radial direction of the thrust bearing seat (8).

3. The heat dissipation structure for an air compressor thrust bearing according to claim 2, characterized in that: The air-cooling groove (9) further includes an annular cooling cavity (13) located inside the air-cooling groove (9), wherein the annular cooling cavity (13) extends to the center hole of the thrust bearing seat (8), and the annular cooling cavity (13) is connected to the air-cooling groove (9).

4. The heat dissipation structure for an air compressor thrust bearing according to claim 3, characterized in that: There are multiple communication grooves between the annular cooling cavity (13) and the air cooling groove (9), and the multiple communication grooves are arranged at intervals.

5. The heat dissipation structure for an air compressor thrust bearing according to claim 3, characterized in that: A plurality of reinforcement parts (14) are provided in the circumferential direction of the central hole of the thrust bearing seat (8), the plurality of reinforcement parts (14) are arranged at equal intervals, and a radial groove (15) communicating with the annular cooling cavity (13) is provided between two adjacent reinforcement parts (14).

6. The heat dissipation structure for an air compressor thrust bearing according to claim 1, characterized in that: The end cooling water channel axially comprises a first cooling portion located in the housing (1) and a second cooling portion located in the integrated radial bearing seat, and the first cooling portion and the second cooling portion are in communication.

7. The heat dissipation structure for an air compressor thrust bearing according to claim 6, characterized in that: The first cooling portion and the second cooling portion are connected via a conformal bending portion.

8. The heat dissipation structure for an air compressor thrust bearing according to claim 6, characterized in that: The second cooling portion extends radially to a middle portion of the integrated radial bearing seat.

9. The heat dissipation structure for an air compressor thrust bearing according to claim 6, wherein: The end cooling water channel comprises a first end water channel (7) and a second end water channel (12) which are spaced apart. Both ends of the first end water channel (7) are connected to a middle cooling water channel opened in the air compressor housing (1). Both ends of the second end water channel (12) are respectively connected to the outlet end and the liquid outlet of the middle cooling water channel. The liquid outlet is opened on the side wall of the housing (1).

10. Air compressor, characterized in that, The invention comprises a heat dissipation structure suitable for an air compressor thrust bearing as described in any one of claims 1 to 9.

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