JP5095252B2 - Construction machine and control method thereof - Google Patents

Description

  The present invention relates to a construction machine including an engine and a motor generator, and more particularly to a construction machine such as a wheel loader that repeatedly accelerates and decelerates and a control method thereof.

  A construction machine such as a wheel loader rarely travels at a constant speed, and requires a travel performance different from that of a general moving body such as an automobile.

  FIG. 50 is a plan view for explaining the V-shaped work that occupies most of the total work by the wheel loader. As shown in FIG. 50A, the wheel loader 100 moves forward toward the earth and sand 102 in order to scoop the earth and sand 102. Next, as shown in FIG. 50 (b), the wheel loader 100 scoops the earth and sand 102. In this case, a strong traction force from zero speed to extremely low speed is required (stall state).

  After the scooping of the earth and sand 102 is completed, as shown in FIG. 50 (c), the wheel loader 100 once moves backward and then turns to start moving forward toward the track 101 (switchback). 50D, after the wheel loader 100 continues to move toward the track 101, the wheel loader 100 loads the earth and sand 102 onto the track 101 as shown in FIG. I do.

  After the loading of the earth and sand 102 is completed, as shown in FIG. 50 (f), the wheel loader 100 once moves backward and then changes its direction and moves forward again toward the earth and sand 102 (switchback).

  In the V-shaped work as described above, a strong traction force is required in an extremely low speed range, and repeated acceleration and deceleration in a low speed range and repeated switchback are forced. Such a requirement is unique to construction machinery.

  Incidentally, in recent years, a hybrid vehicle configured by combining an engine and a motor generator has attracted attention, and various related devices have been developed. As an example, Patent Document 1 proposes a starter for a hybrid vehicle (hereinafter referred to as Conventional Example 1), and Patent Document 2 proposes a drive device for a hybrid vehicle (hereinafter referred to as Conventional Example 2).

  In the first conventional example, the target rotational speed of the gear element connected to the output shaft of the engine is set based on the operation amount of the accelerator, and the electric rotating device is driven to generate the braking torque. The motor generator is controlled so that the rotational speed becomes the set target rotational speed. With such a configuration, the vehicle can be started efficiently.

Conventional example 2 connects the ring gear of the planetary gear device and the motor generator, connects the sun gear of the planetary gear device and the engine, and outputs from the carrier of the planetary gear device to the drive wheel side, while these ring gears. When the carrier and the sun gear have the same coupled rotational speed, two of them are coupled together, and the carrier and the sun gear are integrally rotated at or above the coupled rotational speed. With such a configuration, the vehicle can be started smoothly.
Japanese Patent No. 3344848 JP-A-9-14385

  In order to obtain the traveling performance peculiar to the construction machine as described above, a wheel loader of a medium size or more generally includes a torque converter. FIG. 51 is a graph showing the relationship between the torque ratio to the speed ratio and the efficiency / absorption torque coefficient in the torque converter. FIG. 52 is a graph showing the relationship between the input torque in the torque converter and the engine speed.

  Referring to FIG. 51, it can be confirmed that the torque converter is generally inefficient, and in particular, the efficiency at the low speed ratio is extremely bad (see the R1 region). As described above, the wheel loader requires acceleration and deceleration, travel performance in the low speed region of stall and switchback, and the frequency of use of the low efficiency region of the torque converter is high, so there is room for improvement in terms of efficiency. .

  Referring to FIG. 52, it can be confirmed that the transmission torque depends on the rotational speed of the input shaft (the output shaft of the engine), and therefore, the transmitted torque becomes small when the rotational speed of the engine is low. (See R2 region). Therefore, at the time of acceleration, sufficient torque cannot be transmitted until the engine speed increases. This is a disadvantage for a construction machine that repeatedly accelerates and decelerates over a short distance.

  By the way, when a construction machine such as a wheel loader is used as a hybrid vehicle, in order to achieve a running performance equivalent to or better than that of a torque converter, the driving is mainly performed in a state in which the direct clutch is released in a low speed range, and in this state, It is necessary to control the motor generator torque and the number of shift stages.

  In the conventional examples 1 and 2 described above, the engine torque, the motor generator torque, and the number of shift stages are controlled, although control is performed at the time of starting from the state where the vehicle is stopped until the direct clutch is connected. There is no control. Therefore, it is difficult to realize a hybrid construction machine by applying these conventional examples 1 and 2.

  The present invention has been made to solve such a problem, and the object thereof is to realize good running performance in a low speed range in a state where the direct coupling clutch is not coupled, that is, the direct coupling clutch is released. An object of the present invention is to provide a construction machine that can be used and a control method thereof.

  The inventors of the present invention have intensively studied what kind of configuration should be adopted in order to make a construction machine such as a wheel loader a hybrid vehicle.

  It is known that hybrid systems such as automobiles, trucks, and railways are generally classified into (1) series system, (2) parallel system, and (3) series parallel (split) system. Here, (2) in the case of a parallel system, a torque converter is required. However, as described above, the torque converter has extremely low efficiency in the low speed range. Therefore, it can be said that the parallel system is not suitable for construction machines. In addition, in the case of the parallel system, except for regenerative power generation at the time of deceleration, power is generated when there is a margin in engine output during slow acceleration or constant speed driving, etc., but in the case of a wheel loader when there is such a margin rare. Also, the amount of power generated by deceleration regeneration is small. Therefore, when the parallel system is adopted for the wheel loader, there is a problem that the amount of power generation becomes poor.

  On the other hand, in the case of automobiles of (1) series system and (3) series / parallel system, the torque at the time of starting is only required to accelerate itself. Therefore, when a motor generator that generates a strong torque from zero speed is provided, a transmission is often unnecessary.

  However, as described above, in the case of a wheel loader that requires a strong traction force in a low speed range, it can be said that a transmission is indispensable as long as a practical motor generator is used. 53 to 55 are travel characteristic diagrams showing the relationship between the vehicle speed and the traction force when the wheel loader is driven by a motor generator. In order to obtain the maximum traction force when the gear stage is 1st gear, the reduction ratio is increased to obtain the required driving force with the maximum torque of the motor generator, but on the other hand, the maximum speed of the motor generator Due to this limitation, the maximum speed is limited (in the example shown in FIG. 53, the maximum speed at the first speed is about 7 km / h). The cases where the gear stage is the second speed and the third speed are shown in FIGS. 54 and 55, respectively.

  Thus, since the maximum torque and the maximum rotation speed of the motor generator are in a trade-off relationship, it is difficult to obtain a motor generator that generates a high torque at a low rotation speed and a high maximum rotation speed. Therefore, a transmission is essential in the wheel loader.

  Thus, in the case of a wheel loader, since a transmission is essential, even if a series method or a series-parallel method is adopted, it is not possible to enjoy the advantage that the transmission in these methods is unnecessary. Further, in the series method and the series / parallel method, two sets of motor generators and inverters are required, which causes a problem of increasing the cost.

  In order to solve the above problems, a construction machine of the present invention includes a motor generator connected to a capacitor, an engine, and a planetary gear that couples the motor generator and the output shaft of the engine, and the motor generator A construction machine capable of traveling by transmitting torque generated by the machine and / or the engine to drive wheels, and capable of switching to a plurality of shift stages provided between the planetary gear and the drive wheels. In a state in which the transmission, the direct coupling clutch that directly connects the engine and the transmission, and the direct coupling clutch are released, the number of revolutions of the engine is controlled based on the accelerator opening and the storage amount of the battery, Based on the accelerator opening, the operating state (powering or regeneration) of the motor generator, and the amount of electricity stored in the battery, the shift position of the transmission is controlled and the accelerator opening Comprising vehicle speed, and based on the gear position of the transmission, and a controller configured to determine the torque generated in the engine and the motor generator.

  If comprised in this way, it will become possible to drive | work, repeating charging / discharging within the range of the electrical storage capacity with which the electrical storage device was limited, in the state where engine torque and motor generator torque were kept in balance.

  In the construction machine according to the invention, when the control device has a small amount of electricity stored in the capacitor and the accelerator is depressed, the engine speed is increased while the amount of electricity stored in the capacitor is increased. If the accelerator is depressed, the engine speed may be reduced.

  In the construction machine according to the invention, when the accelerator is depressed and the motor generator is in a power running state, and the amount of power stored in the capacitor is small, While increasing the gear position, the accelerator is depressed and the motor generator is in a regenerative braking state, and when the amount of power stored in the capacitor is large, the gear position of the transmission is decreased. May be.

  The construction machine according to the invention further includes reverse rotation preventing means for preventing reverse rotation of the engine, and the control device is a case where the motor generator is in a regenerative braking state, and The engine may be configured to stop when it is determined that the amount is excessive.

  The construction machine according to the invention further includes a hydraulic pump that drives a cargo handling device, the hydraulic pump is directly connected to the engine, and the control device includes an accelerator opening, a vehicle speed, and a transmission The torque to be generated in the engine and the motor generator may be determined based on the torque required for the operation of the hydraulic pump together with the shift speed.

  In addition, the construction machine according to the invention further includes a hydraulic pump directly connected to the engine, and when the control device is decelerating, by controlling the discharge flow rate and the relief pressure of the hydraulic pump, The engine may be configured to generate a negative torque.

  The construction machine control method of the present invention includes a motor generator connected to a capacitor, an engine, and a planetary gear that couples the motor generator and an output shaft of the engine, and the motor generator and / or the motor A method of controlling a construction machine capable of traveling by transmitting torque generated by an engine to drive wheels, wherein a transmission capable of switching to a plurality of shift stages is provided between the planetary gear and the drive wheels. The engine and the transmission are configured to be directly coupled by a direct clutch, and in a state where the direct clutch is released, the rotation of the engine is determined based on the accelerator opening and the charged amount of the battery. A step of controlling the number of gears, and a step of controlling the switching of the shift stage of the transmission based on the accelerator opening, the operating state of the motor generator, and the amount of charge stored in the battery And a step of, based on the gear position of the accelerator opening, vehicle speed, and the transmission, determining the torque generated in the engine and the motor generator.

  In the construction machine control method according to the invention, the step of controlling the engine speed increases the engine speed when the amount of power stored in the capacitor is small and the accelerator is depressed. On the other hand, when the amount of power stored in the battery is large and the accelerator is depressed, the engine speed may be decreased.

  Further, in the method for controlling a construction machine according to the invention, the step of controlling the switching of the shift speed is a case where an accelerator is depressed and the motor generator is in a power running state, and the amount of power stored in the capacitor Is low, the shift stage of the transmission is raised, while the accelerator is depressed and the motor generator is in a regenerative braking state, and the amount of power stored in the capacitor is large, The gear stage of the machine may be lowered.

  In the construction machine control method according to the invention, the construction machine further includes a hydraulic pump that drives a cargo handling device, the hydraulic pump is directly connected to the engine, and the step of determining the torque includes: The torque to be generated by the engine and the motor generator may be determined based on the torque required for the operation of the hydraulic pump, together with the accelerator opening, the vehicle speed, and the gear position of the transmission.

  ADVANTAGE OF THE INVENTION According to this invention, the construction machine which can drive | work while repeating charging / discharging within the range of the electrical storage capacity with which the electrical storage device was limited, and its control method can be provided.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 is a block diagram showing a configuration of a main part of the construction machine according to Embodiment 1 of the present invention. As shown in FIG. 1, the construction machine 1 according to the present embodiment includes an engine 10 and a motor generator 11. The output shaft of the engine 10 is connected to the sun gear 16a of the planetary gear device, and the output shaft of the motor generator 11 is connected to the gear 17 connected to the ring gear 16b of the planetary gear device. Further, the carrier shaft 18 of the planetary gear device is connected to an electronically controlled transmission 12 that can be automatically switched to a plurality of shift speeds. Note that the planetary gear device is provided with a clutch that directly connects any two of the sun gear 16a, the ring gear 16b, and the carrier shaft 18 (in FIG. 1, the sun gear 16a and the carrier shaft 18 are directly connected).

  The transmission 12 is connected to drive wheels 20 via a differential gear 19. In addition, the transmission 12 and the drive wheel 20 may be directly connected without using the differential gear 19. The transmission 12 and the engine 10 are connected by a direct coupling clutch 15.

  The motor generator 11 is connected to the battery 14 via the inverter 13. The motor generator 11 functions as a regenerative brake and as a power source by power running.

  Although not shown in FIG. 1, the construction machine 1 includes a brake circuit for electronically controlling the mechanical brake, as will be described later.

  The construction machine 1 also includes a control device 2 for controlling operations of the engine 10, the motor generator 11, and the transmission 12. Details of the control device 2 will be described below.

  FIG. 2 is a functional block diagram showing the configuration of the control device provided in the construction machine according to Embodiment 1 of the present invention.

  As shown in FIG. 2, the control device 2 includes a storage amount of the capacitor, an accelerator and brake operation amount, a vehicle speed, a rotation speed and torque of the motor generator 11 (corresponding to a charge / discharge amount of the capacitor), and a rotation of the engine 10. The number and the lever position of the forward / reverse lever are input. Then, the engine speed setting means 201 sets the engine speed based on the input of the charged amount and the accelerator operation amount. The engine speed control means 202 receives inputs of the set speed determined by the engine speed setting means 201, the actual engine speed of the engine 10, and the actual speed of the motor generator 11. Torque required for the engine 10 and the motor generator 11 is calculated from the input, and an engine torque increase / decrease command and a motor generator torque increase / decrease command indicating the calculated results are output.

  The running torque calculating means 203a included in the calculating means 203 calculates the running torque required for running from the operation amount of the accelerator and the brake, and outputs the calculated result as a running torque command. The output torque limit means 204 receives the travel torque command from the travel torque calculation means 203a, and outputs the output torque in order to limit the output of the generator motor when the storage amount of the capacitor is small or excessive with respect to the travel torque command. The output is limited and output to the motor generator torque distribution means 205. The output torque limiting means 204 may be omitted, and the travel torque command may be directly output from the travel torque calculation processing means 203a to the motor generator engine torque distribution means 205.

  In this running torque calculation means 203a, in order to calculate and output the running torque required for running from the accelerator and the brake operation amount, energy is wasted by applying driving force in a state where the brake is applied, It is possible to prevent an operation that puts an excessive load on the brake.

  The motor / generator engine torque distribution means 205 calculates torque distribution to the motor / generator 11 and the engine 11 based on the running torque command as described later, and as a result, the motor / generator torque command and the engine torque command are calculated. Are output to the motor generator 11 and the engine 10, respectively. A signal obtained by adding the motor generator torque increase / decrease command output by the engine speed control means 202 to the motor generator torque command is input to the motor generator 11. On the other hand, the engine 10 receives a signal obtained by adding the engine torque increase / decrease command that is also output to the engine torque command.

  Further, the shift speed calculation means 203b included in the calculation means 203 calculates the shift speed from the accelerator operation amount, the storage amount of the battery, and the operation state (regenerative braking or power running) of the motor generator, as will be described later. Based on the calculated result, a shift command as to whether or not upshifting or downshifting is necessary is output to the transmission 12.

  Note that when the gear stage is switched during deceleration, the calculation means 203 uses a mechanical brake in order to prevent a decrease in steering feeling due to the clutch being disengaged and the deceleration temporarily weakening (torque loss). A mechanical brake command is output to the electronically controlled brake circuit 21 that controls As a result, the mechanical brake is used supplementarily, and the steering feeling can be maintained well even when torque loss occurs in the deceleration stage when switching between forward and reverse (switchback).

  In the basic control of the present invention, the required driving force is calculated from the accelerator operation amount and the vehicle speed by the traveling torque calculating function means, and accordingly, the torque distribution between the motor generator 11 and the engine 10 (the gear of the planetary gear). The motor generator / engine torque distribution means 205 performs the control (uniquely determined by the ratio) and outputs the result to the motor / generator 11 and the engine 10.

  When the accelerator is released while the construction machine is stopped, the normal engine speed becomes the idling speed. However, in the present invention, the engine speed is basically independent of the accelerator operation amount and is mainly set by the charged amount. This is due to the following reason. First, when the engine speed is low, the upper limit speed (that is, the speed at the time of transition from regenerative braking to power running) due to regenerative braking (power generation) of the motor generator 11 with the same gear is low, and when the engine speed is high. Accordingly, the upper limit speed increases. When the vehicle speed exceeds the upper limit speed due to regenerative braking (power generation), the motor generator 11 is in a power running state, but it is impossible to continue power running for a long time because there is a limit in the amount of power storage. Therefore, as will be described later, by setting the engine speed based on the storage amount, it is possible to perform control such that the storage amount is optimal in the regenerative braking region and the powering region of the motor generator 11.

  The control related to the engine speed needs to change only the engine speed so as not to affect the steering feeling. That is, it is necessary to change only the number of times of the engine in a state where the driving force corresponding to the accelerator operation amount is generated by the motor generator 11 and the engine 10. Therefore, in the present invention, as will be described later, the engine speed is changed by changing the torque distribution between the motor generator 11 and the engine 10 while keeping the torque of the carrier shaft, which is the output shaft of the planetary gear, constant. Increase and decrease the speed.

  The upper limit speed due to the regenerative braking described above varies depending on the engine speed. However, when further accelerating, the upper limit speed of the regenerative braking is increased by increasing the number of shift stages (shifting up). In the present invention, when the vehicle speed is increased by acceleration as described above, the engine speed and the number of shift stages are controlled so that the amount of power stored in the battery is optimized.

  Next, more specific processing in the engine number setting means 201, the motor / generator engine torque distribution means 205, and the gear position number calculation means 203b will be described with reference to a flowchart and the like. The following process is a process in a low-speed range in which the direct clutch is released, that is, a process during a V-shaped operation in which acceleration and deceleration are repeated or switchback is repeated, for example.

  FIG. 3 is a flowchart showing a processing procedure for calculating the engine speed setting in the engine number setting means 201. As shown in FIG. 3, first, the engine number setting means 201 determines whether or not the amount of electricity stored in the battery is smaller than a preset lower limit value (set lower limit value) of the stored electricity amount (S101). Here, when it is determined that the storage amount is smaller than the set lower limit value (YES in S101), that is, when it is determined that the storage amount is insufficient, the engine number setting means 201 is depressing the accelerator (accelerator). (S102). If it is determined that the accelerator is not depressed (NO in S102), the process is terminated, and if it is determined that the accelerator is depressed (YES in S102), the engine set speed is increased (S103).

  On the other hand, when it is determined in step S101 that the charged amount is equal to or greater than the set lower limit (NO in S101), that is, when it is determined that the charged amount is sufficient, the engine number setting means 201 determines that the charged amount of the battery is in advance. It is determined whether or not it is larger than the set upper limit value (set upper limit value) (S104). If it is determined that the charged amount is equal to or less than the set upper limit value (NO in S104), that is, if it is determined that the charged amount is appropriate, the process is terminated and it is determined that the charged amount is greater than the set upper limit value. In the case (YES in S104), it is determined whether or not the accelerator is depressed (S105). If it is determined that the accelerator is not depressed (NO in S105), the process is terminated. If it is determined that the accelerator is depressed (YES in S105), the engine set speed is decreased (S103). .

  By performing such a process, it is possible to set an appropriate engine speed according to the amount of stored electricity.

  FIG. 4 is an explanatory diagram illustrating a procedure of an example of a calculation process of the motor generator torque command and the engine torque command in the motor generator engine torque distribution unit 205. In the following description, the case where the output torque limiting means 204 in FIG. 2 is omitted and the running torque calculation means 203a and the motor generator engine torque distribution means 205 are directly connected will be described as an example.

  First, the basic equation of the planetary gear, which is a precondition for the calculation processing of the motor generator torque command and the engine torque command, is shown below.

a _E · ω _E + a _M · ω _M + a _out · ω _out = 0 (1 formula: relationship of rotation speed)
T _E / a _E = T _M / a _M = T _out / a _out (2 formulas: torque relationship)
a _E + a _M + a _out = 0 (3 formulas: relationship of coefficients)
In the above equations, ω _E , ω _M , and ω _out represent the rotation speeds of the engine (sun gear), the motor generator (ring gear), and the output shaft (carrier shaft), respectively, and T _E , T _M , and T _out are , The torque of the engine (sun gear), motor generator (ring gear), and output shaft (carrier shaft), respectively. Further, a _E , a _M , and a _out represent planetary gear parameters.

As shown in FIG. 4, the traveling torque calculation means 203a calculates a torque required for traveling based on the accelerator opening, the vehicle speed, and the number of shift stages, and outputs a traveling torque command (T _out ) as a result of the calculation. Output to the engine torque distribution means 205.

The motor / generator engine torque distribution means 205 receives the travel torque command (T _out ) and calculates T _M = T _out · a _M / a _out and T _E = T _out · a _M / a _out. The motor generator torque command (T _M ) and the engine torque command (T _E ) are output to the motor generator 11 and the engine 10 as the calculation results.

  In the case of normal traveling that does not require a traction force other than the traction force required for the vehicle to travel, the traveling torque is uniquely determined by the accelerator opening and the vehicle speed (including the rate of change of the vehicle speed). In calculating the running torque, the number of shift stages is also taken into consideration so that the same acceleration is obtained regardless of the shift stage. As a result, even if the gear position differs depending on the amount of stored electricity, the same running torque command is output at the same speed and the same accelerator opening, and the same acceleration force is obtained. Therefore, the operator does not need to be aware of the number of gears at that time.

Further, in a traveling situation where traction force such as heavy material traction and earth and sand scooping is required, the vehicle speed does not increase even if the traveling torque command is output, so that it is necessary to increase the traveling torque command as necessary. In this case, the integrator upper limit of the integral control incorporated in the running torque calculation process may be set by the accelerator opening. This function increases the traction force if the vehicle speed does not increase even when the accelerator is stepped on when towing heavy objects or scooping earth and sand. It will be obtained by the accelerator operation.
In such a driving situation where traction force is required, driving by regenerative braking increases, and the power generation state is sustained. Therefore, a shift down is performed as a result of the processing in the shift speed calculation means 203b described later. As a result, the traction force will also increase. Further, when the operator determines that the traction force needs to be increased in advance during the earth and sand scooping work, the work can be smoothly performed by performing the downshift manually.

  FIG. 5 is a flowchart showing the processing steps of the shift speed calculation in the shift speed calculation means 203b. 5, the gear position number calculation means 203b determines whether or not the accelerator is depressed (the accelerator is turned on) (S or not) (S201). Is determined to be depressed (YES in S201), that is, when it is determined that the vehicle is accelerating, the shift speed calculation unit 203b determines whether the motor generator 11 is in a regenerative braking state or a power running state. (S202).

  In step S202, when it is determined that the motor generator 11 is in a power running state (the motor generator 11 is rotating forward) (“power running” in S202), the shift stage number calculation means 203b determines that the storage amount is the set lower limit value. It is determined whether or not it is smaller (S203), and when it is determined that the charged amount is equal to or greater than the set lower limit value, that is, the charged amount is sufficient (NO in S203), the process ends. On the other hand, when it is determined that the charged amount is smaller than the set lower limit value, that is, the charged amount is insufficient (YES in S203), the gear position number calculating means 203b outputs a shift command to the transmission 12 so as to shift up. (S204).

  Further, when it is determined in step S202 that the motor generator 11 is in the regenerative braking state (the motor generator 11 is reversely rotated) (“regenerative braking” in S202), the gear position number calculating means 203b has a stored amount of electricity. It is determined whether or not it is larger than the set upper limit value (S205), and when it is determined that the charged amount is equal to or less than the set upper limit value, that is, the charged amount is appropriate (NO in S205), the process is terminated. On the other hand, when it is determined that the charged amount is larger than the set upper limit value, that is, the charged amount is excessive (YES in S205), the gear position number calculating means 203b outputs a shift command to the transmission 12 so as to shift down ( S206).

  If it is determined in step S201 that the accelerator is not depressed (NO in S201), that is, if it is determined that the engine brake is operating, the gear position number calculation means 203b indicates that the motor generator 11 is in the regenerative braking state. It is determined whether the power running state is present (S207).

  When it is determined in step S207 that the motor generator 11 is in the power running state (“power running” in S207), the gear position number calculation unit 203b determines whether or not the storage amount is less than the set lower limit value (S208). If it is determined that the amount of power storage is equal to or greater than the set lower limit value, that is, the amount of power storage is sufficient (NO in S208), the process ends. On the other hand, when it is determined that the charged amount is smaller than the set lower limit value, that is, the charged amount is insufficient (YES in S208), gear stage number calculating means 203b outputs a shift command to transmission 12 so as to shift down. (S209).

  Further, when it is determined in step S207 that the motor generator 11 is in the regenerative braking state (“regenerative braking” in S207), the gear position number calculation means 203b determines whether or not the charged amount is greater than the set upper limit value. (S210) When it is determined that the charged amount is equal to or less than the set upper limit value, that is, the charged amount is appropriate (NO in S210), the process ends. On the other hand, when it is determined that the charged amount is larger than the set upper limit value, that is, the charged amount is excessive (YES in S210), the gear position number calculating means 203b outputs a shift command to the transmission 12 to shift up ( S211).

  By performing the processing in this manner, it is possible to perform appropriate gear shift switching according to the state of the motor generator and the amount of stored electricity.

  Next, the traveling operation of the construction machine of the present embodiment when the above-described control is performed will be described with reference to the speed diagram of the planetary gear.

  FIG. 6 is a velocity diagram of the planetary gear in the idling state. When the construction machine 1 is stopped and put in the first speed and the engine 10 is rotating at idling, as shown in FIG. 6, no torque is generated in the engine 10, and the vehicle body stops. Therefore, it is zero speed. In this case, the motor generator 11 is in a no-load state and is rotated in the reverse direction. However, strictly speaking, in order for the engine 10 to maintain the idling speed, torque corresponding to the mechanical friction of the engine 10 and the mechanical friction of the motor generator 11 is generated.

  In this state, when the operator depresses the accelerator, the motor generator torque distribution means 205 distributes the torque, and as shown in FIG. 7, the necessary torque is generated in the motor generator 11 and the engine 10, Thereby, torque according to the accelerator operation amount is generated on the output shaft of the planetary gear. As can be seen from FIG. 7, when the rotational speed of the output shaft is low, the motor generator 11 generates torque in the braking direction, and power is generated by regenerative braking. The electric power generated here is stored in a capacitor. Note that the engine speed and the motor generator speed can be controlled by changing the balance between the torque generated by the engine 10 and the torque generated by the motor generator 11. This point will be described later with reference to FIGS.

  As the vehicle body speed increases, the rotation speed of the output shaft increases. As a result, the rotation speed of the motor generator 11 approaches zero as shown in FIG. If acceleration is continued as it is, the speed further increases. As a result, as shown in FIG. 9, the rotational speed of the motor generator 11 becomes zero. When the speed further increases, as shown in FIG. 10, the state of the motor generator 11 shifts from regenerative braking to power running. Here, the motor generator 11 performs power running using the electric power stored in the electric storage device 14 (electric power stored by acceleration by regenerative braking + electric power stored so far).

  When the motor generator 11 is in a power running state, if acceleration is continued with a small amount of stored power, a shift command for shifting up to the transmission 12 is output from the shift stage number calculation means 203b as described above. The As a result, the gear ratio is changed and the rotational speed of the output shaft is lowered, so that the motor generator 11 is reversely rotated again to enter a regenerative braking state, and acceleration is continued while generating power (FIG. 11). Then, if acceleration continues, as shown in FIG. 12, the motor generator 11 will be in a power running state again.

  Thus, by controlling the number of shift steps by the shift step number calculation means 203b, it is possible to continue traveling while repeating charge and discharge within the limited storage capacity of the capacitor.

  Next, the point of controlling the engine speed and the motor generator speed by changing the balance of the torque generated by the engine 10 and the motor generator 11 will be described.

  In the planetary gear, the torque balances of the respective axes coincide with each other as shown in the two basic equations of the planetary gear described above. Therefore, when the torques of the engine 10 and the motor generator 11 are balanced, the engine 10 and the motor generator 11 both accelerate the vehicle body while increasing the rotation speed (increase the rotation speed of the output shaft). Here, when the torque balance between the engine 10 and the motor generator 11 is changed to increase the engine torque, for example, the engine speed increases while the motor generator speed decreases. Thus, by changing the torque balance between the engine 10 and the motor generator 11 and controlling the rotational speeds of the engine 10 and the motor generator 11, it is possible to continue traveling while repeating charge and discharge. Hereinafter, a specific description will be given with reference to FIGS.

  FIGS. 13 to 15 are velocity diagrams of the planetary gear in the acceleration state at the second speed. In any of the cases shown in FIGS. 13 to 15, the rotational speed of the output shaft of the planetary gear is the same. As shown in FIG. 14, when the motor generator 11 is at a transition point between regenerative braking and power running, charging / discharging of electric power is not performed. Here, when the torque balance between the engine 10 and the motor generator 11 is changed to reduce the engine torque, the engine speed decreases while the motor generator speed increases. As a result, the motor generator 11 enters a power running state as shown in FIG. 13 and consumes the electric power stored in the battery 14. On the other hand, when the engine torque is increased, the engine speed increases while the motor generator speed decreases. As a result, as shown in FIG. 15, the motor generator 11 enters a regenerative braking state, and electric power is stored in the capacitor 14.

  Thus, even if the vehicle speed is the same, the motor generator 11 can take either power running or regenerative braking depending on the number of revolutions of the engine 10. Therefore, charging / discharging by the motor generator 11 is performed at the engine speed. It becomes possible to control.

  Next, the travel operation described above will be described with reference to a travel characteristic diagram showing the relationship between speed and traction force. FIG. 16 and FIG. 17 show the engine characteristics and the motor generator characteristics necessary for creating this travel characteristic diagram. The engine does not rotate below the idling rotational speed (or the lowest rotational speed that generates effective torque), and the torque is within the shaded area shown in FIG. 16 (the torque is constant regardless of the engine rotational speed). Shall occur. In practice, the characteristics shown by the engine-generated torque line shown in FIG. 16 are obtained, but for the convenience of creating a running characteristic chart described later, it is as described above.

  Moreover, as shown in FIG. 17, in the motor generator, when it is rotating forward and generating a normal torque, and when it is rotating reversely and generating a reverse torque Is a power running region, and on the other hand, a regenerative braking region is when the vehicle is rotating forward and generating reverse torque, and when it is rotating in reverse and generating positive torque.

  18 and 19 are travel characteristic diagrams showing the relationship between speed and tractive force in the construction machine according to Embodiment 1 of the present invention. Here, FIG. 18 shows a case where the engine speed is low, and FIG. 19 shows a case where the engine speed is high. FIG. 20 is a running characteristic diagram showing the relationship between the speed and traction force in a conventional torque converter-equipped vehicle (torque converter, three-stage transmission, and wheel loader having a mechanism for locking up the torque converter). .

  18, 19, and 20 indicate the output of the mounted motor generator, and as shown in FIG. 20, this output line is the first to third speeds of the conventional torque converter-equipped vehicle. It is set equal to the tractive force up to.

  First, the running characteristics of a conventional torque converter-equipped vehicle will be described with reference to FIG. The relationship between the maximum traction force and the vehicle speed when the shift speed is the first speed is represented by a line indicated by “first speed + T / C traction force” in the figure. When the vehicle speed is zero, as shown in FIG. 51, the torque ratio (output torque / input torque) is large, and as shown in FIG. 52, the transmission torque becomes maximum when the engine speed is maximum. Therefore, the maximum traction force is generated when the engine speed is maximum. As the vehicle speed increases, the speed ratio increases and the torque ratio decreases, so the traction force decreases. Since the torque ratio is zero when the speed ratio is 1, the traction force is also zero. The same applies to the cases of the second speed and the third speed.

  The relationship between the maximum traction force and the vehicle speed when the torque converter is locked up at the first speed, that is, when the direct coupling clutch is engaged, is represented by a line indicated by “first speed direct coupling clutch coupling traction force” in FIG. . In this case, the torque ratio is 1, there is no torque amplification effect by the torque converter, and the traction force is low. In addition, the vehicle cannot travel at a speed lower than the number of revolutions at which the engine generates effective torque (about 3 km / h in the drawing). The same applies to the cases of the second speed and the third speed.

  In the case of the V-shaped work described with reference to FIG. 50, generally, the forward and backward movement is repeated at a speed of up to about 10 km / h. Therefore, in the case of a vehicle equipped with a conventional torque converter (hereinafter referred to as a conventional vehicle), only the operation by the 2-speed torque converter is performed during traveling, and the first speed is used during operations such as scooping earth and sand. Further, when traveling at a high speed of 20 km / h or higher, the torque converter is locked up.

  In FIG. 20, a constant output line indicating the output equivalent of the motor generator 11 in the present embodiment is shown. Considering a case where the motor generator 11 is simply used for traveling, when the maximum torque and the maximum number of rotations of the motor generator 11 are sufficiently large, the traveling performance equivalent to that of the torque converter equipped vehicle can be obtained even without a transmission. Will be obtained. However, in practice, since there is a limit on the maximum torque and a limit on the maximum number of rotations, it is extremely difficult to obtain excellent running performance without a transmission. Therefore, in this invention, it is the structure provided with a transmission.

  Next, traveling characteristics of the construction machine according to the present embodiment will be described with reference to FIGS. 18 and 19. FIG. 18 is created on the assumption that the engine 10 can generate a higher torque on the planetary gear balance than the maximum torque of the motor generator 11. In addition, it is assumed that the engine speed is constant and low.

  18 is determined by the maximum torque of the motor generator shown in FIG. 17, and the maximum speed is also determined by the maximum number of revolutions of the motor generator. The In FIG. 18, the left half area (shaded area) in the characteristics of each gear stage indicates the regenerative braking area of the motor generator, and the right half area indicates the power running area of the motor generator.

  As shown in FIG. 18, in the construction machine of the present embodiment, when the shift speed is 1st, unlike the case of the conventional vehicle, the same traction force is maintained up to a certain speed (about 3 km / h in FIG. 18). Can do. Here, when the shift speed is increased, the maximum traction force decreases, but the maximum speed in the regenerative braking region increases. For this reason, acceleration is generated while generating power by regenerative braking at a low gear position, and power is further accelerated while consuming the stored electric power from a speed range where the rotational speed of the motor generator is normal. When the amount of stored power decreases, the speed is increased and regenerative braking is performed again to generate power and accelerate. In this way, the construction machine of the present embodiment accelerates while repeating charge and discharge.

  In addition, when the high-speed constant speed running is performed as it is, when the speed at which the direct coupling clutch 15 can be coupled (direct coupling clutch coupling speed) is reached, the direct coupling clutch 15 is coupled and the engine 10 travels alone. Usually, the direct coupling clutch 15 may be coupled while maintaining the third speed from the third speed direct coupling clutch released state (running state using regenerative braking or power running of the motor generator 11). However, for example, since the acceleration and deceleration in the third-speed power running state were repeated before the direct-coupled clutch 15 was directly coupled, the amount of power stored in the battery 14 decreased, and as a result, the third-speed directly-coupled clutch coupling speed was reached with the third speed If acceleration is not possible, the direct clutch 15 may be engaged after first shifting to the second speed. In this case, acceleration is performed in the state where the second-speed direct coupling clutch is engaged, and the speed is changed to the third speed after reaching the third-speed direct coupling clutch coupling speed. In the case of traveling in this speed range (higher than about 10 km / h in FIG. 18), it is only necessary to switch the shift stage of the transmission 12 while the direct clutch 15 is engaged. The operation is the same.

  As shown in FIG. 19, when the engine 10 rotates at a high speed, the traction force moves in parallel to the high speed side as much as the rotation speed increases. For example, the maximum traction force when the shift speed is 1st is the same as that when the speed is zero, and covers about 3 km / h, which is a transition point between regenerative braking and power running. In the case of a conventional vehicle, as shown in FIG. 20, the maximum traction force is reduced to about 60% when the vehicle speed is about 3 km / h compared to the case of zero speed. As described above, in the present embodiment, performance that cannot be achieved by the prior art can be obtained.

  Further, referring to the constant output line in FIG. 19, it can be seen that the regenerative braking region from the first speed to the third speed can be covered until the vehicle speed reaches about 7 km / h. This means that even if the power is not stored in the capacitor 14, at this engine speed, traction force equivalent to that of the conventional vehicle can be obtained by regenerative braking (that is, by regenerative braking without consuming electric power). This performance can be obtained only by power generation). For this reason, if the amount of stored electricity is insufficient, the engine speed is increased to widen the speed region covered by regenerative braking, and the vehicle travels while accelerating power generation. On the other hand, if the amount of stored electricity is sufficient, the vehicle is accelerated by power running by lowering the engine speed. As a result, the vehicle can travel by repeatedly generating power by regenerative braking and discharging by powering within a limited range of power storage.

  Next, the traveling operation of the construction machine of the present embodiment when decelerating will be described with reference to FIGS.

  FIG. 21 shows the speed line of the planetary gear when the speed is 2nd speed and the motor generator 11 decelerates when accelerating in a power running state or running at a constant speed. FIG. As shown in FIG. 21, in this case, the motor generator 11 is decelerated while generating power by regenerative braking.

  FIG. 22 shows the speed of the planetary gear when the gear stage is in the second speed and the motor generator 11 decelerates when it is accelerating in a regenerative braking state or traveling at a constant speed. FIG. As shown in FIG. 22, in this case, the motor generator 11 is decelerated while being discharged by powering.

  If it is a case where it is necessary to discharge because the amount of power storage is close to full charge, the speed may be reduced as shown in FIG. However, charging is usually performed by regenerating deceleration energy. Therefore, by lowering the shift speed from the second speed to the first speed, the motor generator 11 is decelerated by shifting from the power running state to the regenerative braking state as shown in FIG.

  Next, the traveling operation of the construction machine according to the present embodiment when performing switchback will be described with reference to FIGS.

  In the case of a conventional vehicle, at the time of switchback, braking energy is consumed by the friction of the clutch and the resistance of the torque converter. On the other hand, in the present invention, the large regenerative energy at the time of switchback is used to generate power, and the power can be stored in the battery 14 to be reused.

  The travel at the time of switchback is roughly divided into two methods according to the shift timing in forward and backward travel. The first method switches between forward and backward travel at an early stage, and the second method switches between forward and backward travel after sufficiently slowing down.

  First, the first method will be described. FIG. 24 is a speed diagram of the planetary gear when the gear stage is moving backward at the second speed or when moving backward at a constant speed. As shown in FIG. 24, in this case, the motor generator 11 is in a power running state. In this state, when the operator operates the forward / reverse lever to the forward side, the control device 2 instructs the transmission 12 to switch the gear position to forward. As a result, the output shaft of the planetary gear (the input shaft of the transmission 12) rotates in the reverse direction at the same rotational speed (provided that the gear ratios for the second-speed forward and reverse gears are the same). . As a result, as shown in FIG. 25, the motor generator 11 is in a regenerative braking state. In the state shown in FIG. 25, since the forward / reverse shift speed is switched, the direction of the drive torque changes from the reverse travel direction (FIG. 24) to the forward travel direction (FIG. 25) (in FIG. 24, the shift speed is the reverse travel speed). Therefore, upward is the reverse acceleration direction, and in FIG. 25, the shift stage is forward, and upward is the forward acceleration direction). When switching the gear position to forward and backward, the rotational speed of the motor generator 11 is controlled while the shift clutch is released, and matches the rotational speed when the shift clutch is connected after the shift is completed. By doing so, the shift shock is suppressed.

  When the forward / reverse switching is completed, the motor generator 11 is regeneratively braked as shown in FIG. Then, after that, the rotational speed of the motor generator 11 increases, and as shown in FIGS. 26 and 27, a transition is made to a power running state. During this time, the engine 10 is controlled by the control device 2 so as to generate torque that balances with the torque of the motor generator 11 necessary for acceleration. Further, as in the case described above, the engine speed is also controlled in order to control the regenerative power generation amount and the power consumption due to power running.

  Next, the second method will be described. FIG. 28 is a speed diagram of the planetary gear when the gear stage is accelerating at the second speed and moving backward or at a constant speed. As shown in FIG. 28, in this case, the motor generator 11 is in a power running state. In this state, when the operator operates the forward / reverse lever to the forward side, the control device 2 keeps the speed stage reverse, reduces the engine speed, and the motor generator 11 performs braking while generating power by regenerative braking. (Figure 29). Deceleration is continued as it is, and the speed is sufficiently reduced as shown in FIG. Thereafter, the control device 2 instructs the transmission 12 to switch the gear position to forward. As a result, as shown in FIG. 31, the vehicle accelerates in the forward direction.

  As shown in FIGS. 32 and 33, when the motor generator 11 is in a power running state, the motor generator 11 further decelerates, power is run from the reverse drive state to the zero speed or the forward speed, and then the shift stage is advanced. There is also a way to switch to. This method reduces the mechanical burden on the transmission 12.

  Next, when the operator switches the forward / reverse lever when traveling at high speed, the following may be performed. If the forward / reverse switching is performed while traveling at a high speed, the rotational speed of the motor generator exceeds the allowable range. Therefore, if the above first method is adopted, normal regenerative deceleration is performed while the rotational speed of the motor generator is within the allowable range, and then forward / reverse switching is performed. On the other hand, when the second method is employed, no particular problem occurs because the forward / reverse switching is performed after the speed is sufficiently lowered.

  Even if either the first method or the second method is adopted, when the gear position is changed during deceleration, the clutch is disengaged and the deceleration is once weakened (torque loss). It is not preferable in terms of feeling. For this purpose, the control device 2 outputs a mechanical brake command to the electronic control brake circuit 21 as described above. As a result, the mechanical brake is used in an auxiliary manner, and the steering feeling can be kept good even when torque loss occurs during forward / reverse switching.

  Next, traveling characteristics of the construction machine of the present embodiment when performing switchback will be described with reference to FIGS. 34 to 38.

  First, a case where the above first method is employed will be described. 34 and 35 are travel characteristic diagrams showing the relationship between the speed and the traction force in the construction machine according to the first embodiment of the present invention when the switchback is performed by the first method. 34 shows the running characteristics immediately before the switchback, and FIG. 35 shows the running characteristics when the shift stage is switched to forward and the motor generator makes a transition from regenerative braking to power running. Since FIG. 34 shows a case where the vehicle is moving backward, the regenerative braking region and the power running region are reversed from the case of moving forward.

  The circles in FIG. 34 indicate the speed and traction force immediately before the switchback. In addition, the circles in FIG. 35 indicate the speed and traction force immediately after the switchback, and the transition of the speed and traction force when accelerating by switching from the second speed power running state (−5 km / h) to the forward speed. Is shown.

  As can be seen from FIG. 35, when the gear position is switched to forward, a large traction force cannot be produced due to the characteristics of the motor generator, so the traction force decreases until the speed increases to some extent (about +2 km / h in FIG. 35). However, after switching to the forward shift stage, the speed can be accelerated without shifting at the second speed, so that the steering feeling is good.

  Next, a case where the second method is employed will be described. 36 to 38 are travel characteristic diagrams showing the relationship between the speed and the traction force in the construction machine according to the first embodiment of the present invention when the switchback is performed by the second method. 36 shows the running characteristics immediately before the switchback, FIG. 37 shows the running characteristics immediately after the switchback until acceleration by regenerative braking of the motor generator, and FIG. 38 shows the motor characteristics by switching the shift stage to forward. The driving characteristics when transitioning from regenerative braking by the machine to power running are shown.

  The circles in FIG. 36 indicate the speed and traction force immediately before the switchback. The circles in FIG. 37 indicate the speed and traction force immediately after the switchback, and the transition of the speed and traction force when accelerating without changing the gear position from the second-speed power running state (−5 km / h). The situation is shown. Furthermore, in FIG. 38, the state of the transition of the speed and traction force when switching from the second-speed regenerative braking state to the forward shift and accelerating is represented by a circle. In FIG. 36 and FIG. 37, although the gear position does not change, the regenerative braking region and the power running region are reversed because the acceleration direction is different.

  In the second method, the speed is not switched but the vehicle speed is reduced by regenerative braking of the motor generator (FIG. 37), then the speed is switched to forward, and the regenerative braking is shifted to power running (FIG. 38). ). As can be seen from FIG. 34 to FIG. 38, unlike the first method, the second method can continuously obtain a large traction force.

  In the case of the second method, it is possible to obtain a larger traction force than in the first method, but the gear position is switched from reverse to forward during the forward acceleration (FIG. 37). From FIG. 38), torque loss occurs at this time, and steering feeling is not preferable. As a countermeasure, an electronically controlled brake may be used as described above.

  As described above, according to the present embodiment, it is possible to travel while repeating charging and discharging within the limited storage capacity of the storage battery. In the case of a huge construction machine such as a wheel loader, a large charge / discharge power is required for the motor generator. At present, a capacitor with a high input / output density has a low energy density like a capacitor, and its storage capacity is limited. The present invention can be said to be suitable for the case of using a capacitor having a high input / output density and a low energy density, such as a capacitor.

(Embodiment 2)
The second embodiment is obtained by adding a one-way clutch to the configuration of the first embodiment to prevent the output shaft of the engine from reversing.

  In the construction machine of the first embodiment, when a state where a large traction force is required at a low speed, such as towing a heavy object or climbing a steep slope, the gear stage becomes the first speed, and the engine speed is reduced. The generator is in a regenerative braking state. If the storage capacity of the battery reaches the upper limit in this state, it is not possible to continue traveling without a function for consuming the generated power. This corresponds to overheating of the torque converter oil in the case of a normal torque converter vehicle. In order to solve this problem, the construction machine of the second embodiment includes a one-way clutch as follows.

  FIG. 39 is a block diagram showing a configuration of a main part of the construction machine according to the second embodiment of the present invention. As shown in FIG. 39, in the construction machine 3 according to the second embodiment, a one-way clutch 30 for preventing the output shaft from reversing is disposed on the output shaft of the engine 10. As described above, the control device 2 stops the engine 10 and runs only by the motor generator 11 when the storage capacity of the capacitor reaches the upper limit. As a result, the stored electric power is consumed. At this time, reverse rotation of the engine 10 is prevented by the one-way clutch 30. As a result, when traveling by the motor generator 11, a situation in which the engine 10 rotates in the reverse direction and no driving force is generated is avoided.

  In addition, since it is the same as that of the case of Embodiment 1 about structures other than the one-way clutch 30, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  FIGS. 40 and 41 are flowcharts showing the flow of operation of the control device in the present embodiment when the running mode is shifted. In the following, the travel mode using the engine and the motor generator is referred to as a normal travel mode, and the travel mode using only the motor generator is referred to as a motor travel mode.

  First, a process for determining whether or not to shift from the normal travel mode to the motor travel mode will be described. As shown in FIG. 40, the control device 2 determines whether the motor generator 11 is in a power running state or a regenerative braking state (S301), and determines that the motor generator 11 is in a regenerative braking state (YES in S301). It is determined whether or not the amount of electricity stored in the battery 14 is greater than the set upper limit value (S302). Here, when it is determined that the charged amount is greater than the set upper limit value (YES in S302), that is, when it is determined that the charged amount is excessive, the control device 2 determines that the engine set rotational speed is greater than a predetermined lower limit value. It is determined whether or not it is lower (S303).

  If it is determined in step S303 that the engine set rotational speed is lower than the lower limit value (YES in S303), the control device 2 determines whether or not the gear position of the transmission 12 is the first speed (S304). Here, when it is determined that the gear position is the first speed (YES in S304), the transition from the normal travel mode to the motor travel mode is executed (S305). The transition to the motor travel mode is executed by the control device 2 stopping the engine 10 and setting the engine torque command to zero.

  If it is determined in step S301 that the motor generator 11 is in a power running state (NO in S301), or if it is determined in step S302 that the charged amount is equal to or less than the set upper limit value (NO in S302), step S303 is performed. When it is determined that the engine set rotational speed is equal to or greater than the lower limit value (NO in S303) and when the gear position is determined not to be the first speed in Step S304 (NO in S304), the motor travel mode There is no transition to.

  Next, processing for determining whether to return from the motor travel mode to the normal travel mode will be described. As shown in FIG. 41, the control device 2 determines whether or not the amount of electricity stored in the battery 14 is less than the set lower limit value (S401). Here, when it is determined that the charged amount is less than the set lower limit value (YES in S401), that is, when it is determined that the charged amount is insufficient, the control device 2 executes the transition from the motor travel mode to the normal travel mode. (S402). The return to the normal travel mode is executed by temporarily stopping the control device 2 and then shifting the transmission 12 after the transmission 12 is neutralized and the engine 10 is started.

FIG. 42 is an explanatory diagram illustrating a procedure of an example of a calculation process of the motor generator torque command and the engine torque command in the motor generator engine torque distribution unit 205. As shown in FIG. 42, the traveling torque calculation means 203a calculates the torque required for traveling based on the accelerator opening, the vehicle speed, and the number of shift stages, and generates a traveling torque command (T _out ) as the calculated result. Output to the engine torque distribution means 205.

The motor generator torque distribution means 205 receives the input of the running torque command (T _out ), calculates T _M = T _out · a _M / a _out and T _E = 0, and uses the motor generation as the calculation result. The machine torque command (T _M ) and the engine torque command (T _E ) are output to the motor generator 11 and the engine 10, respectively.

  Note that the relationship between the speed and the traction force in the motor travel mode, that is, when the engine 10 is stopped and powering only with the motor generator 11 is as shown in FIG. This is a running characteristic of the motor generator 11 itself. However, when the shift speed is forward, it can be powered only in the forward direction, and when the shift speed is reverse, it can be powered only in the reverse direction.

(Embodiment 3)
FIG. 44 is a block diagram showing a configuration of a main part of the construction machine according to Embodiment 3 of the present invention. As shown in FIG. 44, the construction machine 4 of this embodiment includes a hydraulic pump 41 for driving a cargo handling device such as a bucket and an arm, and a cargo handling / steering hydraulic circuit 43 for operating the hydraulic pump 41. ing. The hydraulic pump 41 and the engine 10 are directly connected by gears 42 and 44. Since other configurations are the same as those in the first embodiment, the same reference numerals are given and description thereof is omitted.

  FIG. 45 is a functional block diagram showing the configuration of the control device 2 provided in the construction machine according to Embodiment 3 of the present invention. As shown in FIG. 45, the calculation means 203 includes cargo handling required torque calculation means 203c. The required cargo handling torque calculation means 203c calculates the torque required by the hydraulic pump 41 and outputs a cargo handling engine torque command indicating the calculated result. The cargo handling engine torque command thus output is added to the engine torque command output by the motor generator engine torque distribution means 205 and output to the engine 10. Since the other configuration of the control device 2 is the same as that of the first embodiment, the same reference numerals are given and description thereof is omitted.

FIG. 46 is an explanatory diagram showing a procedure of an example of a calculation process of the motor generator torque command and the engine torque command in the motor generator engine torque distribution unit 205. As shown in FIG. 46, the traveling torque calculation means 203a calculates the torque required for traveling based on the accelerator opening, the vehicle speed, and the number of shift stages, and generates a traveling torque command (T _out ) as the calculated result. Output to the engine torque distribution means 205.

The motor generator torque distribution means 205 receives the travel torque command (T _out ) and calculates T _M = T _out · a _M / a _out and T _E = T _out · a _E / a _out The motor generator torque command (T _M ) and the engine torque command (T _E ) are output to the motor generator 11 and the engine 10 as the calculation results.

The cargo handling engine torque calculation means 203c calculates a torque T _E2 required by the hydraulic pump 41 and outputs a cargo handling engine torque command (T _E2 ) as a result of the calculation. The cargo handling engine torque command (T _E2 ) is added to the engine torque command (T _E ), and the engine torque command (T _E + T _E2 ) after the addition is output to the engine 10. Although not shown in the figure, the required pump discharge amount is also calculated and output to the hydraulic pump, and the discharge amount is used to calculate the torque required by the hydraulic pump.

In the case of the present invention, the vehicle travels in a state where the engine torque and the motor generator torque are balanced. Therefore, when a load is applied to the hydraulic pump 41 directly connected to the engine shaft, as described above, the engine torque (T _E ) required by the traveling system and the cargo handling engine torque (T _E2 ) required by the cargo handling system are used. Must be added to determine the overall engine torque (T _E + T _E2 ).

When the overall engine torque (T _E + T _E2 ) exceeds the torque that can be generated by the engine 10, the control device 2 determines the engine torque (T _E according to the predetermined priority of the traveling system and the cargo handling system. ) And the cargo handling engine torque (T _E2 ), the running torque command (T _out ) is calculated backward from the set value, and the motor generator torque command is also corrected. Thereby, the interference between the traveling system and the cargo handling system can be prevented. This priority may be set by the operator using a lever or the like.

(Embodiment 4)
FIG. 47 is a block diagram showing a configuration of a main part of the construction machine according to Embodiment 4 of the present invention. As shown in FIG. 47, the construction machine 5 of the present embodiment includes a resistance control device 51 between the hydraulic pump 41 and the cargo handling / steering hydraulic circuit 43. As will be described later, the resistance control device 51 is for causing the hydraulic pump 41 to function as a resistor. Since other configurations are the same as those in the third embodiment, the same reference numerals are given and description thereof is omitted.

  FIG. 48 is a functional block diagram showing a configuration of the control device 2 included in the construction machine according to Embodiment 4 of the present invention. As shown in FIG. 48, the calculation means 203 includes an emblem enhancement value calculation means 203d. The emblem enhancement value calculation means 203d calculates a required engine brake value and outputs an emblem increase command indicating the calculated result to the resistance control device 51. Here, the resistance control device 51 combines the discharge flow rate of the hydraulic pump 41 and a relief valve that is electronically controlled based on the input emblem enhancement command, and the hydraulic pump 41 functions as a resistor (emblem enhancement device). Let Since the other configuration of the control device 2 is the same as that of the first embodiment, the same reference numerals are given and description thereof is omitted.

FIG. 49 is an explanatory diagram showing an example of a procedure for calculating an emblem enhancement command in the emblem enhancement value calculation means 203d. As shown in FIG. 49, the traveling torque calculation means 203a calculates the torque required for traveling based on the accelerator opening, the vehicle speed, and the number of shift stages, and generates a traveling torque command (T _out ) as the calculated result. Output to the engine torque distribution means 205.

The motor generator torque distribution means 205 receives the travel torque command (T _out ) and calculates T _M = T _out · a _M / a _out and T _E = T _out · a _E / a _out The motor generator torque command (T _M ) and the engine torque command (T _E ) are output to the motor generator 11 and the engine 10 as the calculation results.

Further, the emblem enhancement value calculation means 203d calculates an emblem value (T _EB ) from the rotational speed of the engine 10 when decelerating, and outputs the engine torque (T _E ) output from the motor generator engine torque distribution means 205. ) _Is subtracted from the emblem value (T _EB ) to calculate the _emblem enhancement value (T _EBcmd ). Thereby, the resistance of the engine itself, that is, the emblem value (T _EB ) and the resistance (T _EBcmd ) generated by the resistance control device 51 become the negative torque generated in the engine output shaft. As a result, a negative torque of T _EB −T _EBcmd = T _E can be generated on the engine output shaft.

  In the present invention, a negative torque is applied to the engine 10 and the motor generator 11 in order to obtain the engine brake as in the conventional vehicle when decelerating. In this case, since the engine 10 cannot actually generate negative torque, the engine 10 decelerates within the range of the resistance of the engine itself (engine brake), but when it is necessary to obtain a stronger deceleration force (steep slope) When going down a hill or when performing switchback, etc.), the resistance control device 51 causes the hydraulic pump 41 to function as a resistor as described above so that negative torque is generated on the output shaft of the engine. Thereby, the energy in the case of decelerating can be collect | recovered by the electric power generation of the motor generator 11, and the burden of a mechanical brake can be reduced.

(Other embodiments)
Although the traveling operation in the state where the direct coupling clutch 15 is released has been described above, the operation of the motor generator 11 in the state where the direct coupling clutch 15 is coupled will be described. When the direct coupling clutch 15 is coupled, the motor generator is connected to the drive shaft. Therefore, in the case of deceleration, electric power is generated by regenerative braking of the motor generator and electric power is stored in the capacitor 14, and the load on the mechanical brake can be reduced. In the case of acceleration, the engine 10 can be assisted by the power running of the motor generator 11 using the surplus power stored in the battery 14.

  Further, the engine 10 and the motor generator 11 are directly connected by coupling the direct coupling clutch 15 and setting the gear position of the transmission 12 to neutral. Since the motor generator 11 is sufficiently powerful compared to a normal starter, the motor generator 11 can be used in place of the starter by directly connecting the engine 10 and the motor generator 11 in this way. Can do. In this case, switching from the neutral to the forward gear is performed by the controller 2 receiving a lever operation signal from the driver outputting a command to the transmission 12. Here, before switching to the forward gear, the control device 2 may start the engine 10 by the motor generator 11 serving as a starter, and then output a command to the transmission 12 to switch the gear to forward. .

  The construction machine and the control method thereof according to the present invention can realize good traveling performance in a low speed range with the direct clutch released, and thus are useful as a construction machine such as a wheel loader and the control method thereof.

It is a block diagram which shows the structure of the principal part of the construction machine which concerns on Embodiment 1 of this invention. It is a functional block diagram which shows the structure of the control apparatus with which the construction machine which concerns on Embodiment 1 of this invention is provided. It is a flowchart which shows the process sequence of the engine setting rotation speed calculation in an engine frequency setting means. It is explanatory drawing which shows the procedure of an example of the calculation process of a motor generator torque command and an engine torque command in a motor generator engine torque distribution means. It is a flowchart which shows the process sequence of the gear stage number calculation in a gear stage number calculation means. It is a speed diagram of the planetary gear in the idling state. It is a speed diagram of the planetary gear in the first speed start (or towing state). It is a speed diagram of the planetary gear in the first speed acceleration state. It is a speed diagram of the planetary gear in the first speed acceleration state. It is a speed diagram of the planetary gear in the first speed acceleration state. It is a speed diagram of the planetary gear in the second speed acceleration state. It is a speed diagram of the planetary gear in the second speed acceleration state. It is a speed diagram of the planetary gear in the second speed acceleration state. It is a speed diagram of the planetary gear in the second speed acceleration state. It is a speed diagram of the planetary gear in the second speed acceleration state. It is a graph which shows the relationship between an engine speed and a torque. It is a graph which shows the relationship between a motor generator rotation speed and a torque. It is a driving | running | working characteristic figure which shows the relationship between the speed and tractive force in the construction machine which concerns on Embodiment 1 of this invention. It is a driving | running | working characteristic figure which shows the relationship between the speed and tractive force in the construction machine which concerns on Embodiment 1 of this invention. It is a driving characteristic figure which shows the relationship between the speed and the forest power in the conventional torque converter loading vehicle. It is a speed diagram of the planetary gear when decelerating. It is a speed diagram of the planetary gear when decelerating. It is a speed diagram of the planetary gear when decelerating. It is a speed diagram of the planetary gear in the case of performing switchback. It is a speed diagram of the planetary gear in the case of performing switchback. It is a speed diagram of the planetary gear in the case of performing switchback. It is a speed diagram of the planetary gear in the case of performing switchback. It is a speed diagram of the planetary gear in the case of performing switchback. It is a speed diagram of the planetary gear in the case of performing switchback. It is a speed diagram of the planetary gear in the case of performing switchback. It is a speed diagram of the planetary gear in the case of performing switchback. It is a speed diagram of the planetary gear in the case of performing switchback. It is a speed diagram of the planetary gear in the case of performing switchback. It is a running characteristic figure which shows the relationship between the speed and tractive force in the construction machine which concerns on Embodiment 1 of this invention when performing switchback by a 1st method. It is a running characteristic figure which shows the relationship between the speed and tractive force in the construction machine which concerns on Embodiment 1 of this invention when performing switchback by a 1st method. It is a running characteristic figure which shows the relationship between the speed and tractive force in the construction machine which concerns on Embodiment 1 of this invention when performing switchback by a 2nd method. It is a running characteristic figure which shows the relationship between the speed and tractive force in the construction machine which concerns on Embodiment 1 of this invention when performing switchback by a 2nd method. It is a running characteristic figure which shows the relationship between the speed and tractive force in the construction machine which concerns on Embodiment 1 of this invention when performing switchback by a 2nd method. It is a block diagram which shows the structure of the principal part of the construction machine which concerns on Embodiment 2 of this invention. It is a flowchart which shows the flow of operation | movement of the control apparatus in Embodiment 2 in the case of performing driving mode transfer. It is a flowchart which shows the flow of operation | movement of the control apparatus in Embodiment 2 in the case of performing driving | running | working mode transfer. It is explanatory drawing which shows the procedure of an example of the calculation process of a motor generator torque command and an engine torque command in a motor generator engine torque distribution means. It is a running characteristic figure which shows the relationship between the speed and traction force of the construction machine which concerns on Embodiment 1 of this invention in motor running mode. It is a block diagram which shows the structure of the principal part of the construction machine which concerns on Embodiment 3 of this invention. It is a functional block diagram which shows the structure of the control apparatus with which the construction machine which concerns on Embodiment 3 of this invention is provided. It is explanatory drawing which shows the procedure of an example of the calculation process of a motor generator torque command and an engine torque command in a motor generator engine torque distribution means. It is a block diagram which shows the structure of the principal part of the construction machine which concerns on Embodiment 4 of this invention. It is a functional block diagram which shows the structure of the control apparatus 2 with which the construction machine which concerns on Embodiment 4 of this invention is provided. It is explanatory drawing which shows the procedure of an example of the calculation process of the emblem enhancement command in an emblem enhancement value calculation means. It is a top view for demonstrating V character work. It is a graph which shows the relationship between the torque ratio with respect to the speed ratio in a torque converter, and an efficiency and an absorption torque coefficient. It is a graph which shows the relationship between the input torque in a torque converter, and an engine speed. It is a driving | running | working characteristic figure which shows the relationship between the vehicle speed and tractive force in the case of driving a wheel loader with a motor generator. It is a driving | running | working characteristic figure which shows the relationship between the vehicle speed and tractive force in the case of driving a wheel loader with a motor generator. It is a driving | running | working characteristic figure which shows the relationship between the vehicle speed and tractive force in the case of driving a wheel loader with a motor generator.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 3, 4, 5 Construction machine 2 Control apparatus 10 Engine 11 Motor generator 12 Transmission 13 Inverter 14 Accumulator 15 Direct coupling clutch 16a Sun gear 16b Ring gear 17 Gear 18 Carrier shaft 19 Differential gear 20 Drive wheel 30 One-way clutch 41 Hydraulic pump 42 , 44 Gear 43 Cargo handling / steering hydraulic circuit 51 Resistance control device

Claims (6)

A motor generator connected to a capacitor; an engine; an output side connected to drive wheels; a transmission capable of switching to a plurality of shift speeds; and the motor generator and the output shaft of the engine, A planetary gear for transmitting torque generated by the motor and / or the engine to the transmission, a direct coupling clutch for directly connecting the engine and the transmission, and operations of the motor generator, the engine, and the transmission. A control device for controlling,
The control device determines a torque to be generated by the engine and the motor generator based on an accelerator opening, a vehicle speed, and a gear position of the transmission,
In the state where the direct clutch is released,
Even when the storage amount of the capacitor is less than the set lower limit value, when the accelerator is depressed, while increasing the rotational speed of the front SL engine, when the storage amount of the capacitor is larger than the set upper limit value there are, when the accelerator is depressed, to reduce the rotational speed of the front SL engine, and,
In a case where and which the accelerator is depressed the motor generator is in force line state, when the storage amount of the capacitor is less than the set lower limit value, while increasing the shift speed before Symbol transmission, the accelerator in a case where and which is depressed the motor generator is in a regenerative braking state, when the storage amount of the capacitor is larger than the set upper limit value, lower the gear position of the transmission,
A construction machine characterized by being configured as follows. A reverse rotation preventing means for preventing reverse rotation of the engine;
The said control apparatus is a case where the said motor generator is in the said regenerative braking state, Comprising: When it determines with the electrical storage amount of the said capacitor | condenser being excessive, it is comprised so that the said engine may be stopped. The construction machine according to 1. A hydraulic pump for driving the cargo handling device;
The hydraulic pump is directly connected to the engine,
The controller is configured to determine a torque to be generated by the engine and the motor generator based on an accelerator opening, a vehicle speed, and a gear stage of the transmission, and a torque necessary for the operation of the hydraulic pump. The construction machine according to claim 1 or 2, wherein A hydraulic pump directly connected to the engine;
3. The control device according to claim 1, wherein the control device is configured to generate a negative torque in the engine by controlling a discharge flow rate and a relief pressure of the hydraulic pump when decelerating. 4. Construction machinery. A motor generator connected to a capacitor; an engine; an output side connected to drive wheels; a transmission capable of switching to a plurality of shift speeds; and the motor generator and the output shaft of the engine, A construction machine control method comprising: a planetary gear for transmitting a torque generated by the machine and / or the engine to the transmission; and a direct coupling clutch for directly coupling the engine and the transmission,
Based on the accelerator opening, the vehicle speed, and the gear position of the transmission, the torque to be generated in the engine and the motor generator is determined,
In the state where the direct clutch is released,
Even when the storage amount of the capacitor is less than the set lower limit value, when the accelerator is depressed, while increasing the rotational speed of the front SL engine, when the storage amount of the capacitor is larger than the set upper limit value there are, when the accelerator is depressed, to reduce the rotational speed of the front SL engine, and,
In a case where and which the accelerator is depressed the motor generator is in force line state, when the storage amount of the capacitor is less than the set lower limit value, while increasing the shift speed before Symbol transmission, the accelerator in a case where and which is depressed the motor generator is in a regenerative braking state, when the storage amount of the capacitor is larger than the set upper limit value, lower the gear position of the transmission, and wherein the To control the construction machine. The construction machine further includes a hydraulic pump that drives a cargo handling device, and the hydraulic pump is directly connected to the engine,
6. The construction according to claim 5, wherein a torque to be generated in the engine and the motor generator is determined based on a torque required for an operation of the hydraulic pump together with an accelerator opening, a vehicle speed, and a gear position of the transmission. How to control the machine.

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