27 and extends from the central air line 63 to the suspension port 58, and a second portion that is disposed outside of the manifold block 27 and extends from the suspension port 58 to one of the air springs 22.

The manifold block 27 further includes a plurality of suspension valves 30, each disposed along one of the spring air lines 60 for inhibiting and allowing air to be conveyed between the manifold block 27 and the respective air springs 22. The suspension valves 30 are each electrically connected with the electronic control unit 44 for being selectively moved between an open position and a closed position. More specifically, each suspension valve 30 allows the passage of air between the air spring 22 and the central air line 63 while in the open position, and each suspension valve 30 inhibits the passage of air between the air spring 22 and the central air line 63 while the suspension valve 30 is in the closed position.

The reservoir tank 38 stores compressed air from the compressor assembly 24 for being distributed to the air springs 22. Because of the stored energy of the compressed air in the reservoir tank 38, the air management system 20 is able to adjust the height of each wheel independently and can elevate the vehicle much quicker due than it would be able to without the reservoir tank 38. The manifold block 27 defines a reservoir port 64 that is fluidly connected to the central air line 63. A portion of the reservoir air line 66 extends from the reservoir tank 38 to the central air line 63 for conveying air between the manifold block 27 and the reservoir tank 38. The reservoir air line 66 includes an inner segment inside the manifold block 27 between the central air line 63 and the reservoir port 64, and an outer segment disposed outside of the manifold block 27 between the reservoir tank 38 and the reservoir port 64 as well as the reservoir port 51.

The manifold block 27 further includes a first reservoir valve 32 and a second reservoir valve 34 that are each disposed in-line with the reservoir port 64 along the reservoir air line 66 inside the manifold block 27 for selectively inhibiting and allowing air to be conveyed between the manifold block 27 and reservoir tank 38. The first and second reservoir valves 32, 34 are each electrically connected with the electronic control unit 44 for selectively opening and closing the reservoir valves 32, 34.

The first and second reservoir valves 32, 34 are positioned in parallel relationship to one another, allowing one or both of the first and second valves 32, 34 to be closed at any given time. More specifically, the reservoir air line 66 splits into a first branch 69 and a second branch 74, and join back together along a portion of the reservoir air line 66 that is connected to the central air line 63. The first reservoir valve 32 is disposed along the first branch 69, and the second reservoir valve 34 is disposed along the second branch 74.

Each of the reservoir valves 32, 34 includes an orifice therein through which air passes. The size of the orifice of the first reservoir valve 32 is smaller than that of the orifice of the second reservoir valve 34. The size of the orifices of the reservoir valves 32, 34 may vary to provide different flow rates between the reservoir tank 38 and manifold block 27. Because of the presence of the pair of reservoir valves 32, 34, three distinct flow rates of air being conveyed through the reservoir valves 32, 34 are possible: 1) maximum flow-when both the first and second reservoir valves 32, 34 are open, 2) first reservoir valve half flow-when the first reservoir valve 32 is opened and the other is closed, and 3) second reservoir valve half flow when the second reservoir valve 34 is opened and the other is closed. It should be appreciated that under certain operating conditions, it can be desirable to utilize different flow rates of air into the air springs 22 to fill the air springs 22 at faster or slower rates.

As illustrated in FIG. 1, the manifold block 27 includes a boost valve 39 arranged in the inner segment of the reservoir air line 66, and defines a boost outlet port 65. The compressor assembly 24 defines a boost inlet port 81, and a boost air line 83 extends between the boost outlet port 65 and the boost inlet port 81. The boost valve 39 is pneumatically connected to the boost air line 83 for selectively directly connecting the reservoir tank 38 and compressor 21. The boost valve 39 may be electrically connected to the electronic control unit 44 for selectively opening and closing the boost valve 39. It should be appreciated that the boost valve 39 may be utilized to provide a reduction in startup torque of the compressor assembly 24 without exhausting the manifold block 27. The boost valve 39 can send additional air pressure via the boost inlet port 81 to the compressor 21 between stages to improve flow output in order to lift the vehicle more quickly.

A pressure sensor 42 is disposed in the manifold block 27 for measuring the pressure in the compressor assembly 24, reservoir tank 38 and/or air springs 22. In order to obtain individual readings of each of the air springs 22 or the reservoir tank 38, the manifold block 27 is evacuated and then the valve(s) 30, 32, 34 for the device in question are momentarily opened such that the pressure that corresponds with the device in question may be measured. As such, it should be appreciated that the pressure sensor 42 may be utilized to verify that the compressor assembly 24, reservoir tank 38 and valves 30, 32, 34 are operating properly.

A dryer control valve 36 is provided in-line with the compressor inlet port 54. The dryer control valve 36 is electrically connected to the electronic control unit 44 for selectively opening and closing the dryer control valve 36. Except when venting in most circumstances, the dryer control valve 36 is left closed to permit one-way flow from the compressor 24 to the manifold block 27 via the lightly sprung valve seat. Thus, when an individual pressure reading is required of either the reservoir tank 38 or of any combination of the air springs 22, the dryer control valve 36 isolates the dryer volume from the manifold block 27. Since the manifold block 27 consists largely of small drilled holes connecting the components together, with the dryer control valve 36 closed, there is very little air volume exposed to the pressure sensor 42 as opposed to the volume of the manifold block 27, dryer 40 and base air line 56. This allows the pressure reading of a specific device to stabilize almost instantaneously and with very little air volume loss, thus making them much faster and more efficient. Accordingly, implementing the dryer control valve 36 improves the speed and efficiency of taking pressure readings.

FIG. 4