Method for controlling the discharge pressure of an engine-driven pump

• US 8,162,619 B2
• Filed: 08/11/2006
• Issued: 04/24/2012
• Est. Priority Date: 08/11/2006
• Status: Active Grant

• Current Assignee: Hale Products, Inc.
• Original Assignee: Hale Products, Inc.
• Inventors: Laskaris, Michael A.
• Primary Examiner(s): Kramer, Devon
• Assistant Examiner(s): STIMPERT, PHILIP EARL
• Application Number:
  US11/464,177
• Publication Number:
  US 20080292472A1
• Time in Patent Office: 2,083 Days
• Field of Search: 417/34, 137/492.5
• US Class Current: 417/34
• CPC Class Codes: F02D 29/04 peculiar to engines driving pumps
• CPC Class Codes: F02D 31/001 Electric control of rotation speed
• CPC Class Codes: F02D 41/021 Introducing corrections for particular conditions exterior to the engine conjoint control of vehicle sub-units for propelling the vehicle B60W30/18
• CPC Class Codes: F02D 41/083 taking into account engine load variation, e.g. air-conditionning
• CPC Class Codes: F04B 49/24 Bypassing
• CPC Class Codes: Y10T 137/777 Spring biased

Abstract

A system for controlling the pressure output of an engine-driven centrifugal fire pump includes a discharge pressure sensor mounted in the discharge line of the pump. A governor varies the rpms of the engine in response to pressure changes detected by the discharge pressure sensor. If the pressure in the system is higher than the desired output pressure when the engine is running at its idle speed an electronically controlled hydraulic relief valve responsive to the discharge pressure sensor operates to relieve the excess pressure in over pressure situations. If the pressure in the system is lower than the desired output pressure when the relief valve is fully closed, the engine speed is increased.

Claims

1. A method for controlling the discharge pressure of an engine-driven centrifugal pump in a system including

the engine having an idle speed Si,

the pump being driven by the engine,

an intake line coupled to the pump for receiving a liquid,

a discharge line coupled to the pump for discharging the liquid,

a pencil strainer mounted on the discharge line,

a pilot control line connected to the discharge line at the pencil strainer, the pencil strainer directing liquid from the discharge line into the pilot control line,

an internal pressure sensor in the pilot control line sensing an actual internal pressure Pa in the discharge line,

a conduit downstream of the internal pressure sensor,

a relief valve in the discharge line and coupled to the conduit, the relief valve being actuatable in a first direction away from a fully closed initial condition, the internal pressure sensor being located upstream of the relief valve, and

a controller operatively connected to the engine, the internal pressure sensor and the relief valve, for varying a speed of the engine, and a condition of the relief valve,

the method comprising the steps of:

a) selecting a desired internal pressure Pd for the discharge line;

b) operating the engine to drive the pump and generate pressure in the discharge line,

c) increasing engine speed if Pa<

Pd while maintaining the relief valve in the fully closed initial condition;

d) decreasing engine speed if Pa>

Pd and the engine speed is greater than Si, while maintaining the relief valve in the fully closed condition;

e) opening the relief valve if Pa>

Pd and the engine speed is equal to or less than Si without adjusting the engine speed; and

f) closing the relief valve if Pa<

Pd and the engine speed is less than or equal to Si; and

g) repeating steps c) through f).

2. The method of claim 1, further comprising the step of e1) maintaining the relief valve in an open condition until Pa<

Pd.

3. The method of claim 1, wherein the relief valve has an outer housing and a rod with a piston on a distal end thereof that sealingly mates with a valve seat within the housing, the housing including a first open end fluidly coupled to the discharge line via a bypass conduit and a side opening coupled to an overflow conduit to allow liquid to flow from the discharge line, a spring being located between a proximal end of the rod and an outside of the housing to bias the rod upwardly toward a fully closed initial condition.

4. A method for controlling the discharge pressure of an engine-driven centrifugal pump in a system including

the engine having an idle speed Si,

the pump being driven by the engine,

an intake line coupled to the pump for receiving a liquid,

a discharge line coupled to the pump for discharging the liquid,

an internal pressure sensor in the discharge line sensing an actual internal pressure Pa in the discharge line,

a relief valve in the discharge line, the relief valve being actuatable in a first direction away from a fully closed initial condition, the relief valve having an outer housing and a rod with a piston on a distal end thereof that sealingly mates with a valve seat within the housing, the housing including a first open end fluidly coupled to the discharge line via a bypass conduit and a side opening coupled to an overflow conduit to allow liquid to flow from the discharge line, a spring acting to bias the rod upwardly toward the fully closed initial condition, a seat located between the spring and the piston which receives pressure to move the rod downwardly away from the fully closed initial condition, and

a controller operatively connected to the engine, the internal pressure sensor and the relief valve, for varying a speed of the engine, and a condition of the relief valve,

the method comprising the steps of:

a) selecting a desired internal pressure Pd for the discharge line;

b) operating the engine to drive the pump and generate pressure in the discharge line and operating the engine above the idle speed Si only when the relief valve is in the fully closed initial condition;

c) increasing engine speed if Pa<

Pd while maintaining the relief valve in the fully closed initial condition;

d) decreasing engine speed if Pa>

Pd and the engine speed is greater than Si, while maintaining the relief valve in the fully closed condition;

e) opening the relief valve if Pa>

Pd and the engine speed is equal to or less than Si without adjusting the engine speed; and

f) closing the relief valve if Pa<

Pd and the engine speed is less than or equal to Si; and

g) repeating steps c) through f).

5. The method of claim 4, wherein the system further includes:

a pencil strainer mounted on the discharge line,

a pilot control line connected to the discharge line at the pencil strainer, the pencil strainer directing liquid from the discharge line into the pilot control line,

the internal pressure sensor in the pilot control line sensing an actual internal pressure Pa in the discharge line,

a conduit downstream of the internal pressure sensor, and

the relief valve coupled to the conduit.

6. A method for controlling the discharge pressure of an engine-driven centrifugal pump in a system including

the engine having an idle speed Si,

the pump being driven by the engine,

an intake line coupled to the pump for receiving a liquid,

a discharge line coupled to the pump for discharging the liquid,

a pencil strainer mounted on the discharge line,

a pilot control line connected to the discharge line at the pencil strainer, the pencil strainer directing liquid from the discharge line into the pilot control line,

an internal pressure sensor in the pilot control line sensing an actual internal pressure Pa in the discharge line,

a conduit downstream of the internal pressure sensor,

a relief valve coupled to the conduit, the relief valve being actuatable in a first direction away from a fully closed initial condition, wherein the first direction is away from a valve seat against the pressure from the discharge line flowing through a bypass conduit to allow liquid to pass through the relief valve, and

a controller operatively connected to the engine, the internal pressure sensor and the relief valve, for varying a speed of the engine, and a condition of the relief valve,

the method comprising the steps of:

a) selecting a desired internal pressure Pd for the discharge line;

b) operating the engine to drive the pump and generate pressure in the discharge line;

c) increasing engine speed if Pa<

Pd while maintaining the relief valve in the fully closed initial condition;

d) decreasing engine speed if Pa>

Pd and the engine speed is greater than Si, while maintaining the relief valve in the fully closed condition;

e) opening the relief valve if Pa>

Pd and the engine speed is equal to or less than Si without adjusting the engine speed; and

f) closing the relief valve if Pa<

Pd and the engine speed is less than or equal to Si; and

g) repeating steps c) through f).

7. The method of claim 6, wherein the relief valve has an outer housing and a rod with a piston on a distal end thereof that sealingly mates with a valve seat within the housing, the housing including a first open end fluidly coupled to the discharge line via a bypass conduit and a side opening coupled to an overflow conduit to allow liquid to flow from the discharge line, a spring being located between a proximal end of the rod and an outside of the housing to bias the rod upwardly toward a fully closed initial condition.