Apparatus and method for controlling a rated system pressure

• US 6,273,686 B1
• Filed: 01/31/2000
• Issued: 08/14/2001
• Est. Priority Date: 01/29/1999
• Status: Expired due to Fees

• Current Assignee: A Roemheld GmbH & Company KG
• Original Assignee: A Roemheld GmbH & Company KG
• Inventors: Pitz, Walter, Kroell, Harald
• Primary Examiner(s): Thorpe, Timothy S.
• Assistant Examiner(s): GRAY, MICHAEL KUHN
• Application Number:
  US09/494,575
• Time in Patent Office: 561 Days
• Field of Search: 417/307, 417/440, 417/300, 417/63, 417/282, 417/292, 137/557, 137/115.18
• US Class Current: 417/307
• CPC Class Codes: F15B 11/028 for controlling the actuating force F15B11/024 takes precedence
• CPC Class Codes: F15B 21/087 Control strategy, e.g. with block diagram
• CPC Class Codes: F15B 2211/20515 Electric motor
• CPC Class Codes: F15B 2211/20538 constant capacity
• CPC Class Codes: F15B 2211/25 Pressure control functions
• CPC Class Codes: F15B 2211/30515 Load holding valves
• CPC Class Codes: F15B 2211/50536 using unloading valves controlling the supply pressure by diverting fluid to the return line
• CPC Class Codes: F15B 2211/5151 being connected to a pressure source and a directional control valve
• CPC Class Codes: F15B 2211/55 for limiting a pressure up to a maximum pressure, e.g. by using a pressure relief valve
• CPC Class Codes: F15B 2211/6309 the pressure being a pressure source supply pressure
• CPC Class Codes: F15B 2211/6653 Pressure control
• CPC Class Codes: G05D 16/2066 using controlling means acting on the pressure source
• CPC Class Codes: Y10T 137/2622 Bypass or relief valve responsive to pressure downstream of outlet valve
• CPC Class Codes: Y10T 137/8326 Fluid pressure responsive indicator, recorder or alarm

Abstract

The rated system pressure in a pressure control system is adjusted through a pressure relief valve (2). In addition to the pressure relief valve (2), the system includes a check valve (4), a pressure sensor (3), a position switch (10), a first pressure adjustment member (13) for the relief valve, a second pressure adjustment member (12) for the check valve (4), an actuator (16), and a microcontroller (15) with a memory (6) and a display (7). Faults caused by pressure adjustment interactions are prevented by permitting an adjustment of the pressure relief valve only if the check valve is fully open and a pump provides pressure. For this purpose the actuator (16) of the check valve in its normal position prevents an adjustment of the pressure relief valve. Opening the check valve by the actuator permits adjusting the pressure relief valve (2) and the switch (10) operated through the actuator sends a signal to the microcontroller to drive the pump. When the check valve is opened, the pressure is equalized throughout the system, so that adjusting the response pressure of the pressure relief valve automatically adjusts the system pressure to a desired rated pressure.

Claims

1. A pressure control system for maintaining a rated system pressure at a pressure input (I) and at a pressure output (O), said pressure control system comprising a pressure supply line (11, 8) for feeding fluid under pressure from said pressure input (I) to said pressure output (O), a pressure return line (9) for returning fluid to a pressure pump (1), a pressure relief valve (2) for connecting said pressure supply line (11) to said pressure return line (9) in response to an excess pressure in said pressure supply line (11, 8), a first pressure adjustment member (13) for adjusting a response pressure of said pressure relief valve (2), a check valve (4) connected in said pressure supply line (11, 8) between said input (I) and said output (O), a second pressure adjustment member (12) for adjusting a response pressure of said check valve (4), a pressure sensor (3) arranged for sensing an actual pressure in said pressure supply line to provide a respective actual pressure signal for operating said pump, a microcontroller (5) having an input connected to receive an output signal from said pressure sensor (3) for generating in said microcontroller (5) a pump control signal, a switch (10) for enabling said pump control signal when said pressure relief valve is to be adjusted to a higher or lower system pressure, a conductor (10A) connecting said switch (10) to said microcontroller (5), and means (16, 17) cooperating with said first and second pressure adjustment members for permitting an adjustment of said pressure relief valve (2) through said first pressure adjustment member (13) only if said second pressure adjustment member (12) is in a position signifying that said check valve (4) is open and said pump (1) is enabled through a signal from said switch (10).

2. The pressure control system of claim 1, wherein said cooperating means (16, 17) comprise an actuator (16) for operating said second pressure adjustment member (12) to open said check valve, said actuator (16) having a configuration normally covering access to said first pressure adjustment member (13) for preventing an adjustment of said first pressure adjustment member (13) under normal working conditions, said actuator (16) comprising an opening (17) so positioned in said actuator (16) that an alignment of said opening (17) with said first pressure adjustment member (13) is enforced when said second pressure adjustment member (12) has opened said check valve (4) in response to an operation of said actuator (16), whereby said pressure relief valve (2) can be adjusted to a rated pressure by said first pressure adjustment member (13) only when said check valve (4) is open and said switch has been activated by the operation of said actuator (16).

3. The pressure control system of claim 2, wherein said switch (10) is ineffective during said normal working conditions of said pump (1) under which the pump is driven only in response to a control signal (14) generated by said microcontroller (5) in response to a measured actual pressure signal from said pressure sensor (3), and wherein said switch (10) provides a pump enabling signal when said actuator begins to move and at the latest when said opening (17) is in alignment with said first pressure adjustment member (13) for enabling a pumping operation when said alignment exists for adjusting said pressure relief valve (2) to a higher rated system pressure.

4. The pressure control system of claim 1, wherein said microcontroller (5) further comprises a first output terminal (14) for providing a pump control signal for operating said pump (1) under normal operating conditions, and a second output terminal (15) for providing system status signals for making corrections in said pressure control system.

5. The pressure control system of claim 1, wherein said microcontroller (5) further comprises a memory (6) for storing any currently adjusted rated system pressure, and a display (7) for displaying any actual pressure sensed in said pressure control system by said sensor (3).

6. The pressure control system of claim 1, wherein said microcontroller (5) comprises a memory (6) for storing at least one rated system pressure, a comparator (CO) for comparing a rated system pressure with an actual system pressure as sensed by said sensor (3) to provide a pump control feedback signal for maintaining said actual system pressure substantially equal to said rated system pressure during normal working conditions.

7. The pressure control system of claim 1, wherein said switch (10) is a reed switch responsive to magnetic action, and wherein said actuator (16) comprises a magnet (10B) for operating said reed switch (10).

17. The pressure control valve system of claim 1, further comprising an analog-to-digital converter connected between an output of said pressure sensor (3) and said microcontroller (5).

8. A pressure control valve system comprising a check valve (4) responsive to a rated system pressure for keeping said check valve open under normal operating conditions as long as a pump is running, a pressure relief valve (2) responsive to an excess pressure exceeding said rated system pressure for detouring fluid under excess pressure to maintain said rated system pressure, a first pressure adjustment member (13) for adjusting said pressure relief valve (2), a second pressure adjustment member (12) for opening said check valve (4), an actuator (16) for operating said second pressure adjustment member (12), said actuator (16) having a configuration for preventing an adjusting of said first pressure adjustment member (13) under normal working conditions by preventing access to said first pressure adjustment member (13), said actuator (16) comprising an opening (17) so positioned in said actuator (16) that an alignment of said opening (17) with said first pressure adjustment member (13) is enforced when said second pressure adjustment member (12) has opened said check valve (4) by an operation of said actuator (16), whereby said pressure relief valve (2) can be adjusted to a rated system pressure by said first pressure adjustment member (13) only when said check valve (4) is open.

9. The valve system of claim 8, further comprising a switch (10) responsive to a movement of said actuator (16) for generating a pump enabling signal when said actuator (16) is moved to or in a position permitting access to said first pressure adjustment member (13).

10. The valve system of claim 9, wherein said switch (10) is a switch responsive to magnetic action, and wherein said actuator (16) comprises a magnet (10B) for operating said switch (10).

11. The valve system of claim 8, further comprising a pressure pump (1) responsive to said switch (10) so that said pump (1) is enabled (ON) when there is access to said first pressure adjustment member (13), and wherein said pump is operable under normal operating conditions without said switch (10), to maintain a rated system pressure.

12. A method for adjusting a rated system pressure in a pressurized fluid supply system including a pump, by means of a pressure relief valve (2) and a check valve (4), said method comprising the following steps:

(a) disabling an adjustment of said pressure relief valve (2) when said check valve (4) is in a normal operating position,

(b) opening said check valve (4), simultaneously enabling an operation of said pump (1) and an adjustment of said pressure relief valve (2) in response to said opening of said check valve (4),

(c) adjusting said pressure relief valve (2) to said rated system pressure, and

(d) returning said check valve (4) to its normal operating position, simultaneously enabling said pump (1) for normal operation and again disabling an adjustment of said pressure relief valve (2) in response to said returning of said check valve into its normal operating position.

13. The method of claim 12, further comprising sensing a position of said check valve (4) to provide a check valve position signal, sensing an actual pressure in said system, and controlling said pump (1) in response to said check valve position signal and in response to said sensed actual pressure in said system when said check valve is open.

14. The method of claim 12, further comprising generating a pump activating feedback signal in response to a sensed actual pressure falling below a stored rated system pressure.

15. The method of claim 12, further comprising storing a rated system pressure, sensing an actual system pressure, comparing said rated system pressure with said actual system pressure for generating a pump control signal for controlling said pump in response to a difference between said actual system pressure and said rated system pressure.

16. The method of claim 15, further comprising generating said pump control signal for driving said pump when said difference indicates that said actual system pressure is below said rated system pressure.