A new energy tension machine and working method thereof

Abstract

The present invention discloses a new energy tension machine and a working method thereof, and relates to the field of tension machines. At present, the tension machines used in the tension line construction of power transmission line projects basically use diesel engines as power. The equipment has high noise and pollutes the environment. The engine has relatively high maintenance costs and poor economy. At the same time, refueling diesel on site is also prone to pollution. The present invention makes full use of the characteristics of the tension machine that it mainly performs passive work. By adding a generator, a power battery, and an electric motor for driving a hydraulic pump, etc., the original diesel engine is cancelled, and the external passive work is converted into electrical energy as much as possible to provide electrical energy for the electric motor driving the hydraulic pump. At the same time, the configured power battery can store excess electrical energy and power the system when the system needs it, making the tension machine more energy-efficient. After canceling the diesel engine, not only will it not pollute the surrounding environment, but it can also greatly reduce the equipment operation noise, optimize the operating environment, and achieve higher environmental protection requirements.

Description

Technical Field

[0001] The present invention relates to the field of tension machines, and in particular to a new energy tension machine and a working method thereof. Background Art

[0002] Tension machines are required in the tensioning and stringing construction of power transmission line projects. However, current tension machines are all powered by diesel engines. Not only are the equipment noisy and pollute the environment, the engine has relatively high maintenance costs and poor economy. At the same time, refueling diesel on site is also prone to pollution.

[0003] The original conventional tension machine is mainly composed of a tension wheel, a reduction mechanism, a hydraulic system, an engine, etc., and its working state is generally as follows: when the tension machine is in place, the engine drives the corresponding hydraulic pump to provide pressure oil for the outrigger cylinder to extend and retract the cylinder; under tension working conditions, the engine drives the corresponding hydraulic pump to provide pressure oil for the fan motor and the tail car motor, and drives the oil replenishment pump to provide relevant brake pressure oil. At the same time, the above-mentioned pressure oil or part of the pressure oil is used as the pressure oil for replenishment of the main hydraulic circuit after operation; when the tension machine is actively driven forward and backward, the engine drives the corresponding hydraulic pump to provide pressure oil for the fan motor and the tail car motor, and provides relevant brake pressure oil. At the same time, the engine drives the main hydraulic pump to provide pressure oil for the active transmission of the tension wheel of the main hydraulic circuit.

[0004] Because the main working state of the tension machine is the tension condition, that is, the passive condition, and in the original conventionally designed tension machine, under the passive tension condition, the tension size is adjusted by adjusting the tension adjustment valve to adjust the main hydraulic circuit pressure size, which corresponds to the resistance size of the stable operation of the tension wheel, and the tension adjustment valve only converts the hydraulic energy into the heat of the hydraulic oil, and dissipates the heat through the radiator, without fully converting and utilizing this part of the energy, and under this condition, the engine still needs to work to provide pressure oil for the stable operation of the fan motor, tail car motor, etc., therefore, there is obvious energy waste.

[0005] Therefore, in order to optimize the operating environment, avoid environmental pollution, and with the continuous improvement of national environmental protection requirements, it is very necessary to develop an energy-saving and environmentally friendly new energy tension machine. Summary of the invention

[0006] The technical problem to be solved and the technical task proposed by the present invention are to improve the existing technical solutions, make full use of the characteristics of the tension machine mainly doing work passively, change the energy acquisition method of the existing tension machine, and provide a new energy tension machine with energy recovery and energy-saving functions and its working method, so as to achieve higher energy-saving and environmental protection requirements. To this end, the present invention adopts the following technical solutions.

[0007] A new energy tension machine comprises a mechanical structure part, a hydraulic system part, a control system part and a power device part. The mechanical structure part comprises a tension wheel, a first gear box connected to the tension wheel, and a brake connected to the first gear box; the hydraulic system part comprises a hydraulic circuit, a tension adjustment valve arranged on the hydraulic circuit, a tension meter, a main hydraulic motor, a main hydraulic pump, a main hydraulic pump oil replenishment pump, a fan pump, a tail car pump, and a brake oil replenishment pump. The brake is connected to the main hydraulic motor, the fan pump is connected to the tail car pump, the tail car pump is connected to the brake oil replenishment pump, and the main hydraulic pump is connected to the main hydraulic pump oil replenishment pump. It is characterized in that it also includes a power generation device connected to the mechanical structure part or the hydraulic system part, which converts external energy into usable electric energy under the passive working condition of the tension machine, and the power generation device comprises a generator and a power battery connected to the generator for storing electric energy; the power device comprises a plurality of motors, the generator and the power battery are connected to the motor, the motor is connected to each hydraulic pump, and the working drive is realized through the control system, and the control system comprises a power battery management module, a motor control module and a hydraulic system control module. By adding a power generation device, power is generated under the passive working condition of the tension machine to provide power for the motor that drives the hydraulic pump and the control system. The configured power battery stores excess power and supplies power to the system when the system power is insufficient. The diesel engine that drives the traditional tension machine is eliminated, and the external passive work is converted into electrical energy as much as possible to supply the tension machine. This makes the tension machine more energy-efficient and efficient, does not pollute the surrounding environment, and meets higher environmental protection requirements.

[0008] As a preferred technical means: the generator is arranged in the mechanical structure part, the mechanical structure part also includes a transfer case, the transfer case is arranged between the brake and the main hydraulic motor, and the generator is connected to the transfer case. The transfer case conveniently realizes the connection between the brake, the main hydraulic motor and the generator, and can achieve speed increase on the generator side, thereby improving the power generation effect.

[0009] As a preferred technical means: the generator is arranged in the mechanical structure part, a speed increasing mechanism is arranged at the large gear of the tension wheel, the generator is directly connected to the speed increasing mechanism, and the speed increasing mechanism is directly connected to the large gear. By connecting the generator with the speed increasing mechanism, the speed increasing of the generator side can be achieved, and the power generation effect can be improved.

[0010] As a preferred technical means: the generator is arranged in the hydraulic system part, a hydraulic drive motor for driving the generator is arranged on the hydraulic circuit between the tension adjustment valve and the tension meter, and the generator is connected to the hydraulic drive motor through the second gear box. The generator is connected to the hydraulic drive motor through the second gear box, and in the passive working condition, the drive power generation is realized, and the second gear box can effectively realize the speed increase and improve the power generation effect.

[0011] As a preferred technical means: the motor includes 1 main motor and 1 auxiliary motor, the fan pump, tail car pump and brake oil supply pump adopt triple pumps, the first fan pump provides pressure oil for the fan motor, the second tail car pump provides pressure oil for the tail car and main hydraulic circuit in tension working condition, and provides pressure oil for the tail car in traction working condition, the third brake oil supply pump provides pressure oil for the brake of the tension wheel, the triple pump is connected to the auxiliary motor, and the main hydraulic pump is connected to the main motor. The main motor and the auxiliary motor independently drive their own hydraulic pumps and are independently controlled. In the passive working condition, the main motor can not work, which can better save energy.

[0012] As a preferred technical means: the main hydraulic pump is connected to the main motor through a reduction box; the triple pump is connected to the auxiliary motor through a reduction device, which can effectively increase the speed of the motor and reduce the cost of the motor.

[0013] As a preferred technical means: the power battery is a detachable battery, including 1 main power battery and 1 spare portable power battery. The total capacity of the power battery is based on the capacity requirement of the tension machine under non-tension conditions, and the capacity is greater than the power consumption of the tension machine when it is actively transmitting backward at rated traction and traction speed for more than 30 minutes.

[0014] Another object of the present invention is to provide a working method of a new energy tension machine, which comprises the following steps:

[0015] 1) When the tension machine is in place, it is powered by the power battery, and the motor drives the corresponding hydraulic pump to provide the outrigger cylinder with pressure oil for cylinder extension and contraction, and the generator is in a no-load state;

[0016] 2) Under tension conditions, the motor drives the corresponding hydraulic pump to provide pressure oil for the fan motor and tail car motor, and drives the brake oil pump to provide relevant brake pressure oil. At the same time, the above pressure oil or part of the pressure oil is used as the pressure oil for the main hydraulic circuit under tension conditions after operation. When the tension machine speed reaches the set value, the generator starts to work, absorbs and converts external energy through the generator, and the absorbed and converted electricity is used to provide the relevant motor and control system, and the excess energy is stored in the power battery;

[0017] 3) When the tension machine is actively driving forward and backward, it is powered by the power battery, and the electric motor drives the corresponding hydraulic pump to provide pressure oil for the fan motor and tail car motor, and provide related brake pressure oil. At the same time, the main motor drives the main hydraulic pump to provide pressure oil for the active operation of the tension wheel of the main hydraulic circuit, and the generators are all in a no-load state.

[0018] Under tension conditions, the generator is in an unloaded state at a low speed, and the tension is entirely borne by the main hydraulic circuit; when it is detected that the pay-off speed increases from a low speed to a preset value, the torque of the generator is automatically increased in steps, and the pressure of the tension adjustment valve in the hydraulic circuit is automatically reduced in steps accordingly. During this process, the external tension value needs to be maintained unchanged; when it is detected that the pay-off speed decreases from a high speed to a value close to the preset value, the pressure of the tension adjustment valve is automatically increased in steps, and the torque of the generator is automatically reduced to no-load in steps accordingly. During this process, the external tension value needs to be maintained unchanged; when the tension machine actively drives forward or backward, the generator is in a no-load state. The control idea of ​​adding a generator is effectively realized.

[0019] The mechanical structure is provided with multiple sets of tension wheels. When two sets of tension wheels are required to be connected, the control of the two generators is controlled by a tension adjustment valve set therein, and a tension adjustment valve is kept in a corresponding relationship with the two sets of generators, which effectively realizes the control of the generators when the tension wheels are connected.

[0020] Beneficial effects:

[0021] 1. Make full use of the characteristics of the tension machine that it mainly works passively, and cancel the existing diesel engine by adding generators, power batteries and electric motors for driving hydraulic pumps, so as to convert as much external passive work as possible into electrical energy, and provide electrical energy for the electric motors driving the hydraulic pumps. At the same time, the configured power batteries can store excess electrical energy and power the system when the system needs it, making the tension machine more energy-efficient. After canceling the diesel engine, not only will it not pollute the surrounding environment, but it can also greatly reduce the noise of equipment operation, optimize the operating environment, and achieve higher environmental protection requirements.

[0022] 2. By connecting the generator through the speed increasing mechanism, the generator side can be accelerated and the power generation effect can be improved.

[0023] 3. The main motor and the auxiliary motor drive their own hydraulic pumps independently and are controlled independently of each other. Under passive working conditions, the main motor can be stopped, which can better save energy.

[0024] 4. The main hydraulic pump is connected to the main motor through a reduction gearbox, which can effectively increase the speed of the motor and reduce the cost of the motor.

[0025] 5. The power battery effectively realizes the storage of electric energy. In addition, in order to avoid the tension machine being in low-speed operation for a long time and causing insufficient power reserves, a spare portable power battery is configured so that it can be conveniently brought back to the base for charging. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The present invention is a schematic diagram of a transfer case connected to a generator.

[0027] Figure 2 It is a schematic diagram of the present invention using a hydraulic drive motor to connect a generator.

[0028] Figure 3 It is a schematic diagram of the main hydraulic pump connected to the electric motor of the present invention.

[0029] FIG. 4 is a schematic diagram of a triple pump connected to an electric motor according to the present invention.

[0030] In the figure: 1- tension wheel; 2- first gearbox; 3- brake; 4- main hydraulic motor; 5- transfer case; 6- generator; 7- tension adjustment valve; 8- hydraulic drive motor; 9- second gearbox; 10- tension gauge; 11- main motor; 12- reduction box; 13- main hydraulic pump; 14- main hydraulic pump oil replenishment pump; 15- auxiliary motor; 16- fan pump; 17- tail car pump; 18- brake oil replenishment pump. DETAILED DESCRIPTION

[0031] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings.

[0032] Example 1

[0033] like Figure 1 , 3 As shown in , 4, a new energy tension machine includes a mechanical structure part, a hydraulic system part, a control system part and a power device part. The mechanical structure part includes a tension wheel 1, a first gear box 2 connected to the tension wheel 1 and a brake 3 connected to the first gear box 2, a transfer case 5 connected to the brake 3 and a generator 6 connected to the transfer case 5; the hydraulic system part includes a hydraulic circuit, a tension adjustment valve 7 arranged on the hydraulic circuit, a tension meter 10, a main hydraulic motor 4, a main hydraulic pump 13, a main hydraulic pump oil replenishment pump 14, a fan pump 16, a tail car pump 17, and a brake oil replenishment pump 1 8. The brake 3 is connected to the main hydraulic motor 4, the fan pump 16 is connected to the tail car pump 17, the tail car pump 17 is connected to the brake oil replenishment pump 18, the main hydraulic pump 13 is connected to the main hydraulic pump oil replenishment pump 14, and also includes a power generation device connected to the mechanical structure part to convert external energy into usable electric energy under the passive working condition of the tension machine, the power generation device includes a generator 6 and a power battery connected to the generator 6 for storing electric energy; the power device includes a plurality of motors, the generator 6 and the power battery are connected to the motor, the motor is connected to each hydraulic pump, and the working drive is realized through the control system. The control system mainly includes a power battery management module, a motor control module and a hydraulic system control module.

[0034] In order to facilitate the arrangement of the generator, the generator 6 is arranged in the mechanical structure part, and the mechanical structure part also includes a transfer case 5. The transfer case 5 is arranged between the brake 3 and the main hydraulic motor 4, and the generator 6 is connected to the transfer case 5. The transfer case 5 conveniently realizes the connection between the brake 3, the main hydraulic motor 4 and the generator 6, and can realize acceleration on the generator 6 side to improve the power generation effect.

[0035] In order to better save energy, the motor includes a main motor 11 and an auxiliary motor 15, and the fan pump 16, the tail car pump 17 and the brake oil supply pump 18 use a triple pump. The first fan pump 16 provides pressure oil for the fan motor, the second tail car pump 17 provides pressure oil for the tail car and the main hydraulic circuit in the tension working condition, and provides pressure oil for the tail car in the traction working condition. The third brake oil supply pump 13 provides pressure oil for the brake 3 of the tension wheel. The triple pump is connected to the auxiliary motor 15, and the main hydraulic pump 13 is connected to the main motor 11. The main motor 11 and the auxiliary motor 15 independently drive their own hydraulic pumps and are independently controlled. In the passive working condition, the main motor 11 can not work, which can better save energy.

[0036] In order to reduce the cost of the motor, the main hydraulic pump 13 is connected to the main motor 11 through the reduction box 12; the triple pump can be connected to the auxiliary motor 15 through the reduction device. The speed of the motor can be effectively increased and the cost of the motor can be reduced.

[0037] In order to make the power battery meet the working requirements of the tension machine, one main power battery and one spare portable power battery are configured to realize the functions of electric energy storage and power supply for the system. The total capacity of the power battery needs to meet the capacity requirements of the tension machine under non-tension conditions, and its capacity is greater than the power consumption of the tension machine for about 30 minutes of active backward transmission operation at rated traction and traction speed. At the same time, in order to effectively solve the problem of insufficient power reserves caused by the tension machine being in low-speed operation for a long time, a spare portable power battery is configured to be easily brought back to the station for charging, so as to supplement the stored power of the tension machine.

[0038] A working process of a new energy tension machine includes the following steps:

[0039] 1) When the tension machine is in place, it is powered by the power battery, and the motor drives the corresponding hydraulic pump to provide the outrigger cylinder with pressure oil for cylinder extension and contraction, and the generator is in a no-load state;

[0040] 2) Under tension working condition, the motor drives the corresponding hydraulic pump to provide pressure oil for the fan motor and tail car motor, and drives the brake oil pump 18 to provide pressure oil for the relevant brake 3. At the same time, the above pressure oil or part of the pressure oil is used as the pressure oil for the main hydraulic circuit after operation. When the tension machine operating speed reaches the set value, the generator 6 starts to work, and the generator 6 absorbs and converts external energy. The absorbed and converted electric energy is used to provide the relevant motor and control system, and the excess energy is stored in the power battery;

[0041] 3) When the tension machine is actively driving forward and backward, the power battery supplies power, and the motor drives the corresponding hydraulic pump to provide pressure oil for the fan motor and tail car motor, and provides pressure oil for the relevant brake 3. At the same time, the main motor 11 drives the main hydraulic pump 13 to provide pressure oil for the main hydraulic circuit tension wheel 1 to actively operate, and the generators are all in a no-load state. The working control method is reliable and can effectively realize the normal operation of the new energy tension machine.

[0042] Under tension conditions, it is difficult for the generator 6 to maintain a stable tension at a low speed. Therefore, in terms of control, when the tension wheel 1 rotates at a low speed, the generator is in an unloaded state, that is, it is in an idling state, and the tension is entirely borne by the main hydraulic circuit; when it is detected that the pay-off speed increases from a low speed to a preset value, the torque of the generator is automatically increased in steps, and the pressure of the tension adjustment valve 7 in the hydraulic circuit is automatically reduced in steps accordingly. During this process, the external tension value needs to be maintained unchanged; when it is detected that the pay-off speed decreases from a high speed to a value close to the preset value, the pressure of the tension adjustment valve 7 is automatically increased in steps, and the torque of the generator is automatically reduced to no-load in steps accordingly. During this process, the external tension value needs to be maintained unchanged; when the tension machine actively drives forward or backward, the generator 6 is in a no-load state. The control idea of ​​adding a generator 6 is effectively realized.

[0043] The mechanical structure is suitable for multiple tension wheels 1. When two tension wheels 1 are in parallel, the control of two generators 6 is controlled by a tension adjustment valve 7 set therein; other control methods are the same as the operation of a single tension wheel, that is, one tension adjustment valve 7 is still maintained to form a corresponding relationship with two generators. The control of the generators in the case of parallel tension wheels is effectively realized.

[0044] In this example, the power battery adopts a ternary lithium battery or a lithium iron phosphate battery commonly used in electric vehicles.

[0045] Example 2

[0046] Different from the above example 1, the generator 6 is arranged in the mechanical structure part, and a speed increasing mechanism is arranged at the large gear of the tension wheel 1, and the generator 6 is connected to the speed increasing mechanism. By connecting the generator 6 with the speed increasing mechanism, the acceleration of the generator 6 side can be achieved, and the power generation effect can be improved.

[0047] Example 3

[0048] like Figure 2 As shown, different from the above example 1, the generator 6 is arranged in the hydraulic system part, and a hydraulic drive motor 8 for driving the generator 6 is arranged on the hydraulic circuit between the tension adjustment valve 7 and the tension meter 10, and the generator 6 is connected to the hydraulic drive motor 8 through the second gear box 9. The generator 6 is connected to the hydraulic drive motor 8 through the second gear box 9, and in the passive working condition, the drive power generation is realized, and the second gear box 9 can effectively realize the speed increase and improve the power generation effect.

[0049] above Figure 1-4 The new energy tension machine and its working method shown are specific embodiments of the present invention, which have embodied the substantial characteristics and progress of the present invention. According to actual use needs and under the guidance of the present invention, equivalent modifications in shape, structure, etc. can be made to them, which are all within the protection scope of this scheme.

Claims

1. A new energy tension machine, comprising a mechanical structure part, a hydraulic system part, a control system part and a power device part, wherein the mechanical structure part comprises a tension wheel (1), a first gear box (2) connected to the tension wheel (1), and a brake (3) connected to the first gear box (2); the hydraulic system part comprises a hydraulic circuit, a tension adjustment valve (7) arranged on the hydraulic circuit, a tension meter (10), a main hydraulic motor (4), a main hydraulic pump (13), a main hydraulic pump oil replenishment pump (14), a fan pump (16), a tail car pump (17), and a brake oil replenishment pump (18), wherein the brake (3) is connected to the main hydraulic motor (4), the fan pump (16) is connected to the tail car pump (17), the tail car pump (17) is connected to the brake oil replenishment pump (18), and the main hydraulic pump (13) is connected to the main hydraulic pump oil replenishment pump (14), characterized in that: It also includes a power generation device connected to the mechanical structure part or the hydraulic system part, which converts external energy into usable electric energy under the passive working condition of the tension machine, the power generation device includes a generator (6) and a power battery connected to the generator (6) for storing electric energy; the power device includes a plurality of electric motors, the generator (6) and the power battery are connected to the electric motors, the electric motors are connected to each hydraulic pump, and the working drive is realized through a control system, the control system includes a power battery management module, a motor control module and a hydraulic system control module; Under tension conditions, the generator (6) is in an unloaded state at a low speed, and the tension is entirely borne by the main hydraulic circuit. When it is detected that the pay-off speed increases from a low speed to a preset value, the torque of the generator is automatically increased in steps, and the pressure of the tension adjustment valve (7) in the hydraulic circuit is automatically reduced in steps accordingly. During this process, the external tension value needs to be maintained unchanged. When it is detected that the pay-off speed decreases from a high speed to a value close to the preset value, the pressure of the tension adjustment valve (7) is automatically increased in steps, and the torque of the generator is automatically reduced to no-load in steps accordingly. During this process, the external tension value needs to be maintained unchanged. When the tension machine actively drives forward or backward, the generator (6) is in a no-load state.

2. A new energy tension machine according to claim 1, characterized in that: The generator (6) is arranged in the mechanical structure part, and the mechanical structure part also includes a transfer case (5). The transfer case (5) is arranged between the brake (3) and the main hydraulic motor (4), and the generator (6) is connected to the transfer case (5).

3. A new energy tension machine according to claim 1, characterized in that: The generator (6) is arranged in the mechanical structure part, a speed increasing mechanism is arranged at the large gear of the tension wheel (1), the generator (6) is directly connected to the speed increasing mechanism, and the speed increasing mechanism is directly connected to the large gear.

4. A new energy tension machine according to claim 1, characterized in that: The generator (6) is arranged in the hydraulic system part, and a hydraulic drive motor (8) for driving the generator (6) is arranged on the hydraulic circuit between the tension adjustment valve (7) and the tension meter (10), and the generator (6) is connected to the hydraulic drive motor (8) through a second gear box (9).

5. The new energy tension machine according to claim 1, characterized in that: The electric motor comprises a main electric motor (11) and an auxiliary electric motor (15); the fan pump (16), the tail car pump (17) and the brake oil supply pump (18) adopt a triple pump; the first fan pump (16) provides pressure oil for the fan motor; the second tail car pump (17) provides pressure oil for the tail car and the main hydraulic circuit in the tension working condition and provides pressure oil for the tail car in the traction working condition; the third brake oil supply pump (18) provides pressure oil for the brake (3) of the tension wheel; the triple pump is connected to the auxiliary electric motor (15); the main hydraulic pump (13) is connected to the main electric motor (11).

6. A new energy tension machine according to claim 5, characterized in that: The main hydraulic pump (13) is connected to the main motor (11) via a reduction gear box (12); the triple pump can be connected to the auxiliary motor (15) via a reduction gear.

7. A new energy tension machine according to claim 1, characterized in that: The power battery is a detachable battery, including 1 main power battery and 1 spare portable power battery. The total capacity of the power battery is based on the capacity requirement of the tension machine under non-tension conditions, and the capacity is greater than the power consumption of the tension machine when it is actively transmitting backward at rated traction and traction speed for more than or equal to 30 minutes.

8. A working method of a new energy tension machine according to claim 1, characterized in that The following steps are involved: 1) When the tension machine is in place, it is powered by the power battery, and the motor drives the corresponding hydraulic pump to provide the outrigger cylinder with pressure oil for cylinder extension and contraction, and the generator is in a no-load state; 2) Under tension conditions, the motor drives the corresponding hydraulic pump to provide pressure oil for the fan motor and the tail car motor, and drives the brake oil supply pump (18) to provide pressure oil for the relevant brake (3). At the same time, the pressure oil or part of the pressure oil is used as the pressure oil for the main hydraulic circuit under tension conditions after operation. When the tension machine operating speed reaches the set value, the generator (6) starts to work, and the generator (6) absorbs and converts external energy. The absorbed and converted electricity is used to provide the relevant motor and control system, and the excess energy is stored in the power battery; 3) When the tension machine is actively driven forward or backward, the power battery supplies power, and the electric motor drives the corresponding hydraulic pump to provide pressure oil for the fan motor and the tail car motor, and to provide pressure oil for the related brakes (3). At the same time, the main electric motor (11) drives the main hydraulic pump (13) to provide pressure oil for the active operation of the tension wheel (1) in the main hydraulic circuit, and the generators are all in a no-load state.

9. The working method of a new energy tension machine according to claim 8, characterized in that: The mechanical structure is provided with a plurality of tension wheels (1). When two tension wheels (1) are required to be used in parallel, the control of the two generators (6) is commonly controlled by a tension adjustment valve (7) set therein, and a corresponding relationship is maintained between the tension adjustment valve (7) and the two generators.

Images