WO2014198065A1

WO2014198065A1 - Engine power boost system and method

Info

Publication number: WO2014198065A1
Application number: PCT/CN2013/077265
Authority: WO
Inventors: Weiqing LIN; Johannes Dehn
Original assignee: Robert Bosch Gmbh
Priority date: 2013-06-14
Filing date: 2013-06-14
Publication date: 2014-12-18
Also published as: DE112013007158T5; CN105658936B; CN105658936A

Abstract

An engine power boost system for an internal combustion engine, a corresponding method and an excavator are disclosed. The system comprises sensing means for sensing a load intended to be overcome by the engine during the operation of the engine, and an engine controller connected with the engine and the sensing means for receiving load information from the sensing means and controlling the operation of the engine. The engine controller is configured to activate an engine power boost by increasing the limit of fuel injection quantity of the engine from a standard injection quantity limit to an increased injection quantity limit when the load information indicates that the load is increased over a load threshold, and to end the engine power boost by recovering the standard injection quantity limit after the engine power boost has been activated for a preset duration. The engine can be protected effectively by means of the system and method of the disclosure.

Description

ENGINE POWER BOOST SYSTEM AND METHOD

Technical Field

The invention relates to an engine power boost system and method which may be applied in vehicles or machinery equipped with an internal combustion engine.

Background Art

A vehicle or a machine driven by an electrically controlled internal combustion engine is equipped with an electric controller for controlling the torque/speed of the engine. Once an overload risk is detected, the engine is controlled to increase the engine full load limit to enable the engine operating with a higher torque. The increased limit may work within a short period, after which, the original limit will turn back to control engine power again.

For example, patent application publication US2007028892A1 discloses an internal combustion engine with speed recovery power boost, in which, when an operating speed reduction of the engine is determined to be caused by an external load, the operation of a fuel supply system is controlled to increase the injection quantity of fuel above a normal maximum fuel output. Then, the operation of the fuel supply system returns to normal after the engine speed is recovered.

For engine speed recovery by engine power boost, engine endurance capability is challenged by increased fuel injection quantity for long time running. Further, it is desired to cooperatively control the functional components, which are also driven by the engine, during the speed recovery period for protecting the engine and these functional components.

Summary of the Invention

An object of the invention is to provide an improved engine power boost function by means of which the engine is effectively protected from damage during power boost.

According to one aspect of the invention, there provides an engine power boost system for an internal combustion engine, comprising: sensing means for sensing a load intended to be overcome by the engine during the operation of the engine; and an engine controller connected with the engine and the sensing means for receiving load information from the sensing means and controlling the operation of the engine; wherein the engine controller is configured to activate an engine power boost by increasing the limit of fuel injection quantity of the engine from a standard injection quantity limit to an increased injection quantity limit when the load information indicates that the load is increased over a load threshold, and to end the engine power boost by recovering the standard injection quantity limit after the engine power boost has been activated for a preset duration.

Preferably, the engine controller is further configured to disable the engine power boost in a disable duration which follows directly the preset duration.

Preferably, the engine controller is further configured to monitor the output torque of the engine, and to activate the engine power boost when the output torque of the engine is close to or on a standard engine full load curve which corresponds to the standard injection quantity limit.

Preferably, the engine controller is further configured to monitor the fuel injection quantity of the engine, and to activate the engine power boost when the fuel injection quantity of the engine is higher than a fuel injection quantity threshold.

Preferably, the fuel injection quantity threshold is about 90% to about 100% of the standard injection quantity limit.

Preferably, the engine controller is further configured to monitor the speed of the engine, and to activate the engine power boost when the speed loss of the engine is higher than a speed loss threshold.

Preferably, the speed loss threshold is about 40 rpm to about 60 rpm.

Preferably, the engine power boost system further comprises functional-component controlling means which is integrated in or coupled with the engine controller for controlling a functional component which is driven by the engine to create an operating power against the load; wherein the functional-component controlling means is configured to increase the operating power of the functional component during the preset duration.

Preferably, the functional-component controlling means is further configured to reduce the operating power of the functional component during preset duration when the speed loss and/or the torque of the engine are higher than preset maximum levels.

Preferably, the engine is an engine of a vehicle or a machine, such as a construction machine.

According to another aspect of the invention, there provides an excavator comprising an engine; a hydraulic system driven by the engine; and an engine power boost system as described above, for providing engine power boost function to the engine. Preferably, the engine power boost system further comprises a hydraulic protection module which is configured to increase the fluid pressure in the hydraulic system when the engine power boost is activated and to decrease or release the fluid pressure in the hydraulic system during the preset duration when the speed loss and/or the torque of the engine are higher than preset maximum levels.

Preferably, the hydraulic protection module is either integrated in the engine controller or formed as a separate hydraulic controller coupled between the engine controller and the hydraulic system.

According to yet another aspect of the invention, there provides an engine power boost method for an internal combustion engine, comprising: sensing a load intended to be overcome by the engine during the operation of the engine; activating an engine power boost by increasing the limit of fuel injection quantity of the engine from a standard injection quantity limit to an increased injection quantity limit when the load information indicates that the load is increased over a load threshold; and ending the engine power boost by recovering the standard injection quantity limit after the engine power boost has been activated for a preset duration.

Preferably, the engine power boost method further comprises: disabling the engine power boost in a disable duration which follows directly the preset duration.

Preferably, the engine power boost method further comprises: increasing the operating power of a functional component during the preset duration, the functional component being driven by the engine to create an operating power against the load.

Preferably, the engine power boost method further comprises: reducing the operating power of the functional component during preset duration when the speed loss and/or the torque of the engine are higher than preset maximum levels.

According to the invention, the engine is effectively protected from damage in engine power boost period.

Brief Description of the Drawings

Figure 1 is schematic view of a machine which comprises an engine power boost function according to a first embodiment of the invention;

Figure 2 is a diagram showing the full load limit curve of an engine.

Figure 3 is a diagram showing the shift of the full load limit curve according to the engine power boost function of the invention. Figure 4 is a diagram showing some conditions which are considered in the engine power boost function of the invention.

Figure 5 is a logic chart for the engine power boost function of the invention.

Figure 6 is schematic view of a machine which comprises an engine power boost function according to a second embodiment of the invention;

Figure 7 is a diagram showing cooperative control of the full load limit curve and a hydraulic system of the machine according to an embodiment of the invention;

Figure 8 is a diagram showing exemplary fuel injection control strategies of the engine power boost function of the invention.

Figure 9 is flow chart showing the power boost function according to an embodiment of the invention; and

Figure 10 is flow chart showing the hydraulic protection function according to an embodiment of the invention.

Detailed Description of Preferred Embodiments

Now some preferred embodiments of the engine power boost function according to the invention will be described with reference to the drawings.

First, it is noted that the engine power boost function of the invention can be used in various vehicles and machinery equipped with an internal combustion engine, such as construction machinery, for example, the excavator shown in Figure 1.

As can be seen from Figure 1 , the excavator comprises an internal combustion engine 10 for driving the excavator to move on the ground, a hydraulic system 20, two pumps of which are illustrated, also driven by the engine 10 for conducting digging operations, and an electronical engine controller 30 which is connected with the engine 10 and the hydraulic system 20 for receiving operation parameters of them and controlling operations of them.

The hydraulic system 20 is subjected to a load 40 during a digging operation, which results in pressure change in the hydraulic system 20. The engine controller 30 receives the pressure in the hydraulic system 20 sensed by sensing means as a representative of the load, operation parameters of hydraulic system 20, such as the velocities of the pumps, and operations of the engine 10, such as the velocity and torque of it, to control operations of the engine 10 and the hydraulic system 20. It is known that each engine has a fixed full load (speed-torque) curve for a given fuel injection quantity, as shown in Figure 2. That is to say, at each speed, the engine can only deliver a fixed maximum torque. Generally, the engine shall work at a point under the full load curve, for example, point 1 in Figure 2. The torque may be increased to point 2 which is near the full load curve if the load of the engine increases. Then, if the torque is continuously increased, the operation state moves to point 3 along the full load curve from point 2. At point 3, the torque is increased to the maximum level, but the engine speed is decreased relative to that at point 2. The decreasing of engine speed may result in lowering down of the engine performance. For example, if the engine speed is decreased form point 3 where the maximum torque is presented, the torque is also decreased along with the engine speed, so that point 4 with both low torque and low speed may be reached, or even the engine may stop at point 5.

With a given fuel injection quantity, the engine can be operated with the fixed full load curve for any time. Thus, once the excavator is overloaded, engine speed drop is detected, and then hydraulic fluid will be relieved back to an oil tank, which results in energy loss.

Turning to the excavator shown in Figure 1, once an overload is detected in the hydraulic system 20, such as the excavator hitting a big stone during an earth digging operation, the engine 10 coupled with hydraulic system has the risk to be overloaded. In this situation, according to a basic concept of the engine power boost function of the invention, the quantity of the fuel injected into the engine 10 is controlled by the engine controller 30 to increase within a short preset duration At, so that the engine 10 runs out of the standard engine full load curve El and operates by an increased engine full load curve E2 to perform an engine power boost function, as shown in Figure 3. The arrowed curve T may represent the real operating torque of the engine 10, showing the change of the real operating torque in a digging operation. It can be seen that, for each engine speed n, the maximum possible torque Tl defined by the standard engine full load curve El can be increased to the maximum possible torque T2 defined by the increased engine full load curve E2, while the real operating torque T_acti_ve of the engine can be between the maximum possible torques Tl and T2.

It can be seen also from Figure 3 that there are two intersecting points CI and C2 between the real operating torque curve T and the standard engine full load curve El . When the real operation state of the engine 10 reaches or will reach the first intersecting point CI, the engine controller 30 increases the fuel injection quantity to present the increased engine full load curve E2. Then, after the preset duration At, the engine controller 30 recovers the standard fuel injection quantity to present the standard engine full load curve El . The preset duration At is determined so that, on one hand, the engine overload ability is increased effectively to overcome increased loads generally met in digging operation, and on the other hand, deterioration of the engine endurance performance is limited.

Ideally, the preset duration At is determined so that, for most cases, the second intersecting point C2 falls with the preset duration At. However, in the condition that the load is too large to be overcome even by the increased engine full load curve E2, the engine controller 30 also recovers the standard engine full load curve El after the preset duration At to protect the engine 10, as discussed below.

It is noted that the engine power boost function can be triggered either automatically by the engine controller 30 as described above or manually by an operator of the excavator via a button.

For triggering the engine power boost function, some or all the conditions as described below shall be met.

1) An > a limit, wherein An equals to the current engine speed n at an operating point PI in the standard engine full load curve El minus the engine speed nO which corresponds to the maximum torque level Tlmax on the standard engine full load curve El, as shown in Figure 4 (if An is too small, quick decreasing of the engine speed may happen even after the engine power boost function is triggered);

2) the engine torque reaches or is close to the standard engine full load curve El (at operating point P2);

3) the pump out pressure of the hydraulic system 20 increases over a limit; and

4) the engine speed drop is over a limit.

At operating point P2, the engine power boost function is triggered so that the engine torque may be increased from that presented at operating point P2 to that presented at operating point P3 which is close to the increased engine full load curve E2, without significant decreasing of the engine speed.

Then, if the engine torque increases further, the operation state shifts from operating point P3 to operating point P4 along the increased engine full load curve E2, wherein operating point P4 is the maximum torque level T2max on the increased engine full load curve E2, and T2max is higher than Tlmax by AT. In this stage, the engine speed decreases more quickly than that happens in the stage from operating point P2 to operating point P3.

After the preset duration At, the engine power boost function is ended, regardless whether the operating state of the engine 10 falls into the area under the standard engine full load curve El . Then, in a further duration directly after the preset duration Δΐ, the engine power boost function is disabled for protecting the engine 10 from being damaged by repetitive initiating the engine power boost function. Thus, this further duration may be referred to as disable duration.

Figure 5 is a logic chart for the engine power boost function conducted by the engine controller 30. In block Bl, the engine speed and/or the hydraulic pressure is sensed. Block Bl is coupled with Block B2 in which the first or standard engine full load torque limit is stored and Block B3 in which the second or increased engine full load torque limit is stored. Blocks B2 and B3 are coupled with Block B4 which performs a switch function.

On the other hand, Block B5 is a trigger which sends out a trigger signal as indicated in Block B6. Block B7, which is downstream of Block B6, reverses the trigger signal in Block B6. Block B8, which is downstream of Block B7, allows the trigger signal in Block B7 to be transmitted to Block B9 after a preset duration. The trigger signal in Block B6 is also transmitted to Block B9. Block B9 performs an "and" function to the trigger signals from Blocks B6 and B8 and sends a result signal to Block B4, which selectively connect one of Blocks B2 and B3 to a downstream Block B10 in which the engine torque limit is set as either standard or increased. In a downstream Block Bl l, the fuel injection quantity is determined.

When Block B9 receives the same signal from Blocks B6 and B8, it sends a signal to Block B4 to switch on Block B3 to start the engine power boost function. Then, after the preset duration, Block B9 receives opposite signals from Blocks B6 and B8 and sends a signal to Block B4 to switch on Block B2 to recover the standard engine operation by ending the engine power boost function.

In the excavator shown in Figure 1 as the first embodiment of the invention, an engine power boost function can be achieved by the electronical engine controller 30. The electronical engine controller 30 may be either an ECU (electronical control unit) of the engine 10 or a separate controller coupled with the engine ECU.

According to a second embodiment of the invention, a hydraulic protection function is added in addition to the power boost function as described in the first embodiment. Specifically, the excavator shown in Figure 6 comprises an internal combustion engine 10 for driving the excavator to move on the ground, a hydraulic system 20 also driven by the engine 10 for conducting digging operations, an electronical engine controller 30 which is connected with the engine 10 for receiving operation parameters of it and controlling the operation of it, and a hydraulic controller 50 coupled with or integrated in the electronical engine controller 30 and connected with the hydraulic system 20 for receiving the pressure in the hydraulic system 20 caused by a load 40 and controlling the operation of the hydraulic system 20.

The excavator shown in Figure 6 can perform the engine power boost function and the hydraulic protection function cooperatively. Specifically, Figure 7 shows in its right and left parts the shift of the full load limit curves of the engine 10 and the hydraulic system 20 respectively.

The shift of the full load limit curve of the engine 10 is similar to that shown in Figure 3, that is to say, the engine 10 has a standard engine full load curve El and an increased engine full load curve E2, while the hydraulic system 20 has a standard hydraulic full load curve LI and an increased hydraulic full load curve L2 correspondingly. When the engine 10 is controlled by the engine controller 30 to run out of the standard engine full load curve El and operates by the increased engine full load curve E2 to perform an engine power boost function, the hydraulic system 20 is controlled by the hydraulic controller 50 to shift from the standard hydraulic full load curve LI to the increased hydraulic full load curve L2.

According to the excavator shown in Figure 6 and with reference to Figure 7, when the load 40 is increased, the engine power boost function is initiated either automatically by the engine controller 30 or manually by an operator of the excavator via a button at an operating point PI of the engine which is close to the standard engine full load curve El . Then the engine full load curve is increased from El to E2. The operating point of the engine may be shifted from PI to P2 which is on or slightly higher than the standard engine full load curve El . The engine torque and the hydraulic pressure at operating point P2 are both higher than that at operating point PI .

As the load 40 is increased continuously, the operating point of the engine may be shifted from P2 to P3 which is on the increased engine full load curve E2. In this condition, the engine controller 30 will judge whether the load 40 can be overcome. If so, the engine torque and the hydraulic pressure will be decreased and the operating point of the engine will be shifted to an operating point P2' which is on the standard engine full load curve El, and then the engine controller 30 will stop the engine power boost function. On the other hand, if the engine controller 30 judges that the load 40 can not be overcome, for example, by continuous increasing of engine torque and the hydraulic pressure from operating point P3, the engine controller 30 instructs the hydraulic controller 50 to actively reduce the pressure in the hydraulic system 20 to force the operating point of the engine to be shifted from P3 to P2, so that the hydraulic system 20 is protected from being damaged under continued high pressure. When the pressure in the hydraulic system 20 is actively reduced, the torque of the engine 10 is also reduced thereby. Thus, the engine 10 is also protected by the hydraulic protection function.

As a supplementary protection to the engine, two timers are provided in the engine power boost function, as shown in Figure 8. Specifically, Timer 1 provides the preset duration At in which the engine power boost function is activated, and Timer 2, which follows Timer 1, provides the disable duration in which the engine power boost function is disabled. In the disable duration provided by Timer 2, the engine power boost function cannot be activated even if the boost condition is satisfied, such as engine torque reached full load limit or speed drop over the trigger setting. Specifically, in Figure 8, horizontal line "Q lim" represents a standard fuel injection quantity limit, horizontal line "Q lim" represents a fuel injection quantity when engine power boost is triggered, and horizontal line "Boost" represents an increased fuel injection quantity limit in the engine power boost state. Curve "Case 1" illustrates an condition of fuel injection control where overload has been overcome in the preset duration At, and curve "Case 2" illustrates an condition of fuel injection control where overload has not been overcome in the preset duration At. According to the invention, the engine power boost function cannot be activated in the disable duration no matter whether the hydraulic pressure is reduced below the trigger condition (for example, Case 1) or not (for example, Case 2). After the disable duration provided by Timer 2, the engine controller 30 will judge whether the engine power boost function should be re-activated.

By means of the disable duration, deterioration of the engine endurance performance can be further limited.

Figure 9 shows a flow chart of an engine power boost process which can be performed by both the first and second embodiments as described above.

In step S 1 , the engine power boost process is initiated.

Then, in step S2, the engine controller judges whether the engine power boost function is switched on. If the result is "No", then the process goes to step S20 to keep the engine power boost function off; and if the result is "Yes", then the process goes to step S3.

In step S3, the engine controller waits, with the engine power boost function in an active or ready to be activated state.

Then, in step S4, the engine controller judges whether the fuel injection quantity is higher than a certain high percentage (such as about 90%) of a standard limit of fuel injection quantity (which corresponds to the standard engine full load curve) and the speed loss of the engine is higher than a preset level (such as about 40 rpm to about 60 rpm, for example, 40 rpm). If the result is "No", then the process goes back to step S3; and if the result is "Yes", then the process goes to step S5.

In step S5, the engine controller sets an increased limit of fuel injection quantity (which corresponds to the increased engine full load curve).

Then, in step S6, the engine controller judges whether the real fuel injection quantity is less than a certain percentage (such as about 70%) of the increased limit of fuel injection quantity. If the result is "Yes", then the process goes back to step S3; and if the result is "No", then the process goes to step S7.

In step S7, the engine controller judges whether the fuel injection quantity is higher than the standard limit of fuel injection quantity (higher than 100% of it). If the result is "No", then the process goes back to step S5; and if the result is "Yes", then the process goes to step S8.

In step S8, the engine power boost function is activated and/or kept by the engine controller. Meanwhile, the count of Timer 1 is increased by an increment.

Then, in step S9, the engine controller judges whether the count of Timer 1 is larger than a predetermined value. If the result is "No", then the process goes back to step S8 so that the engine power boost state is continued; and if the result is "Yes", then the process goes to step S10.

In step S10, the engine power boost function is disabled. Meanwhile, the count of Timer 2 is increased by an increment.

Then, in step S 11 , the engine controller judges whether the count of Timer 2 is larger than a predetermined value. If the result is "No", then the process goes back to step S10 so that the engine power boost is continued to be disabled; and if the result is "Yes", then the process goes back to step S3.

Figure 10 shows a flow chart of a hydraulic protection process which can be performed by both the first and second embodiments as described above in combination with the engine power boost process shown in Figure 9.

In step S101, the hydraulic protection process is initiated by the hydraulic controller or the engine controller.

Then, in step SI 02, the hydraulic controller or the engine controller judges whether the speed loss and/or the torque of the engine are higher than preset maximum levels. If the result is "No", then the process goes back to step S101; and if the result is "Yes", then the process goes to step SI 03.

In step SI 03, the hydraulic controller or the engine controller reduces the hydraulic output of the hydraulic system to actively lower down the hydraulic pressure.

According to the invention, by means of the preset duration during which the engine power boost function is activated and after which the engine power boost function is ended, the engine is effectively protected from damage during power boost, and deterioration of the engine endurance performance is limited.

Further, by means of the disable duration which follows directly the preset duration and in which the engine power boost function is disabled, the engine endurance performance is further limited from deterioration.

Furthermore, by means of a hydraulic protection function which can be activated in combination with the engine power boost function, the hydraulic system and the engine are both protected from damage under extremely large loads.

It is appreciated that, although the invention has been described above with reference to an excavator, the concept of the invention is applicable in various vehicles and machinery equipped with an internal combustion engine.

It is further appreciated that, although the hydraulic protection function has been described above for protecting the hydraulic system of the excavator, similar protection function can be applied to various functional components or the vehicles and machinery which are also driven by the engine of them and are subjected to the load.

While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the invention. The attached claims and their equivalents are intended to cover all the modifications, substitutions and changes as would fall within the scope and spirit of the invention.

Claims

CLAIMS:

1. An engine power boost system for an internal combustion engine, comprising: sensing means for sensing a load intended to be overcome by the engine during the operation of the engine; and an engine controller connected with the engine and the sensing means for receiving load information from the sensing means and controlling the operation of the engine; wherein the engine controller is configured to activate an engine power boost by increasing the limit of fuel injection quantity of the engine from a standard injection quantity limit to an increased injection quantity limit when the load information indicates that the load is increased over a load threshold, and to end the engine power boost by recovering the standard injection quantity limit after the engine power boost has been activated for a preset duration.

2. The engine power boost system of claim 1, wherein the engine controller is further configured to disable the engine power boost in a disable duration which follows directly the preset duration.

3. The engine power boost system of claim 1 or 2, wherein the engine controller is further configured to monitor the output torque of the engine, and to activate the engine power boost when the output torque of the engine is close to or on a standard engine full load curve which corresponds to the standard injection quantity limit.

4. The engine power boost system of any one of claims 1 to 3, wherein the engine controller is further configured to monitor the fuel injection quantity of the engine, and to activate the engine power boost when the fuel injection quantity of the engine is higher than a fuel injection quantity threshold.

5. The engine power boost system of claim 4, wherein the fuel injection quantity threshold is about 90% to about 100% of the standard injection quantity limit.

6. The engine power boost system of any one of claims 1 to 5, wherein the engine controller is further configured to monitor the speed of the engine, and to activate the engine power boost when the speed loss of the engine is higher than a speed loss threshold.

7. The engine power boost system of claim 6, wherein the speed loss threshold is about 40 rpm to about 60 rpm.

8. The engine power boost system of any one of claims 1 to 7, further comprising functional-component controlling means which is integrated in or coupled with the engine controller for controlling a functional component which is driven by the engine to create an operating power against the load; wherein the functional-component controlling means is configured to increase the operating power of the functional component during the preset duration.

9. The engine power boost system of claim 8, wherein the functional-component controlling means is further configured to reduce the operating power of the functional component during preset duration when the speed loss and/or the torque of the engine are higher than preset maximum levels.

10. The engine power boost system of any one of claims 1 to 9, wherein the engine is an engine of a vehicle or a machine, such as a construction machine.

11. An excavator comprising: an engine; a hydraulic system driven by the engine; and an engine power boost system of any one of claims 1 to 7, for providing engine power boost function to the engine.

12. The excavator of claim 11, wherein the engine power boost system further comprises a hydraulic protection module which is configured to increase the fluid pressure in the hydraulic system when the engine power boost is activated and to decrease or release the fluid pressure in the hydraulic system during the preset duration when the speed loss and/or the torque of the engine are higher than preset maximum levels.

13. The excavator of claim 11 or 12, wherein the hydraulic protection module is either integrated in the engine controller or formed as a separate hydraulic controller coupled between the engine controller and the hydraulic system.

14. An engine power boost method for an internal combustion engine, comprising: sensing a load intended to be overcome by the engine during the operation of the engine; activating an engine power boost by increasing the limit of fuel injection quantity of the engine from a standard injection quantity limit to an increased injection quantity limit when the load information indicates that the load is increased over a load threshold; and ending the engine power boost by recovering the standard injection quantity limit after the engine power boost has been activated for a preset duration.

15. The engine power boost method of claim 14, further comprising: disabling the engine power boost in a disable duration which follows directly the preset duration.

16. The engine power boost method of claim 14 or 15, further comprising: increasing the operating power of a functional component during the preset duration, the functional component being driven by the engine to create an operating power against the load.

17. The engine power boost method of claim 16, further comprising: reducing the operating power of the functional component during preset duration when the speed loss and/or the torque of the engine are higher than preset maximum levels.